SRP704 1994 Cattlemen's Day - K-State ASI · Factors Influencing First-Service Conception and Overall Pregnancy Rates in ... Urea is a common source of rumen degrad-able nitrogen

This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

CONTENTS

NUTRITION

Level of Urea in High Grain Diets: Finishing Steer Performance . . . . . . . . . . . . . . . 1

Level of Urea in High Grain Diets: Nutrient Digestibility, Microbial ProteinProduction, and Rumen Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Source and Level of Crude Protein for Implanted Finishing Steers . . . . . . . . . . . . . . 7

D- vs L-Methionine Utilization by Growing Steers . . . . . . . . . . . . . . . . . . . . . . . 11

Effect of Rumen-Escape Protein Level on Feedlot Performance andCarcass Traits of Implanted vs Nonimplanted Yearling Steers . . . . . . . . . . .13

Payout Characteristics of Anabolic Agents from Synovex®, Finaplix®,and Revalor® Implants in Finishing Yearling Steers . . . . . . . . . . . . . . . . . .16

Roughage Levels and Comparison of Mixed Rations vsSelf-Feeders in Whole Shelled Corn Finishing Programs. . . . . . . . . . . . . . 20

Roughage Level and Corn Processing in Finishing Diets: Subacute Acidosis . . . . . . . 23

Effects of Alfalfa Form and Level on Subacute Acidosis. . . . . . . . . . . . . . . . . . . 26

The Effect of Sodium Bicarbonate Level on Rumen Metabolism inSteers with Induced Subacute Acidosis . . . . . . . . . . . . . . . . . . . . . . . . . 29

Supplemental Chromium and Revaccination Effects onPerformance and Health of Newly Weaned Calves . . . . . . . . . . . . . . . . . . 31

Effects of Supplemental Trace Minerals and Prevaccination on Stressed Calves. . . . . 35

Effect of Morning vs Evening Feeding of Limit-Fed Holsteinsduring Summer Months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

PRODUCTION AND FIELD STUDIES

Implanting Suckling Heifer Calves: Growth and Subsequent Performance . . . . . . . . . 40

Effect of Stage of Growth and Sampling Procedure on theTrace Mineral Content of Kansas Native Grass . . . . . . . . . . . . . . . . . . . . 43

The Effect of Copper Sulfate and Zinc Oxide in a Drenchon the Gain and Health of Newly Arrived Calves . . . . . . . . . . . . . . . . . . . 45

The Effect of Fourplex® on Gain and Health of Newly Arrived Calves . . . . . . . . . . .46

i


The Effect of Protected Lysine-Methionine on Gain and Health ofNewly Arrived Calves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

The Effect of Mass Treatment with Micotil® at Arrival on theHealth and Performance of Long-Hauled Calves . . . . . . . . . . . . . . . . . . . . 50

The Effect of Feeding Different Levels of Aureomycin® in a MineralMixture to Stocker Cattle Grazing Native Grass . . . . . . . . . . . . . . . . . . . . 51

Effect of Lasalocid and Length of Morning Grazing on Weight andShrink of Steers Grazing Bromegrass Pastures . . . . . . . . . . . . . . . . . . . . . 53

Commercial Cattle Producers: Bull Selection Criteria . . . . . . . . . . . . . . . . . . . . . 56

Economies of Size for Kansas Beef Cow Production . . . . . . . . . . . . . . . . . . . . . .60

Efficacy of Using Parasitic Wasps to Control Stable Flies in Kansas Feedlots . . . . . . .64

HARVESTED FORAGES

In Vitro Dry Matter Digestibilities of Selected Forage SorghumSilages as Influenced by Plant Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Effect of Grain Content on the Nutritive Value of Whole Plant Corn Silage . . . . . . . .70

Agronomic Traits and Growing Cattle Performance for Whole-PlantCorn and Forage and Grain Sorghum Silages . . . . . . . . . . . . . . . . . . . . . 74

Effect of Sorghum Hybrid and Grain Supplementation on theUtilization of Silage-Based Rations for Growing Cattle . . . . . . . . . . . . . . . . 77

Location Effects on Forage Production and Quality among SelectedPioneer Corn Hybrids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

RANGE AND GRAZING STUDIES

Effect of Grain Type in Supplements and Supplementation Frequencyon the Performance of Beef Cows Grazing Winter Range . . . . . . . . . . . . . .86

Dormant, Tallgrass-Prairie Forage: Influence of Rumen Degradable Protein onIntake by Beef Cows and Fermentation Characteristics . . . . . . . . . . . . . . . . 89

Evaluation of the Potential of Supplements to Substitute for Range Forage. . . . . . . . 92

Continuous-Culture Fermentation as a Tool for Forage Evaluation . . . . . . . . . . . . . 95

Relationships between Lignin Content and Fermentabilityof Intact and Chemically Treated Bluestem Fiber . . . . . . . . . . . . . . . . . . . 98

i i


PHYSIOLOGY

Pubertyand Breeding Performance of Beef Heifers Developed at DifferentRates of Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Influence of Dietary Energy Levels on Reproductive Function andFertility in Yearling Beef Heifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Factors Influencing First-Service Conception and Overall Pregnancy Rates inCommercial Beef Heifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Restricting Calf Presence without Suckling Shortens PostpartumInterval to First Ovulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Effect of Monensin on Weight Gain, Growth Traits, and Semen Characteristicsin Yearling Beef Bulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

BREEDING AND GENETICS

Among-Breed Estimates of Heritability for Birth Weight,Weaning Weight, and Mature Cow Weight . . . . . . . . . . . . . . . . . . . . . . . 116

Heritabilities and Genetic Correlations for Birth Weight, WeaningWeight, and Yearling Weight in Polled Hereford Cattle . . . . . . . . . . . . . . . 119

MEATS

Decontamination of Beef Carcasses and Subprimal Cuts . . . . . . . . . . . . . . . . . . . . 121

Effect of Lactic Acid Sprays on Shelf Life and MicrobiologicalSafety of Beef Subprimals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Polyvinylchloride-Packaged Loin Strip Steaks from Vacuum-Packaged Beef StripLoins Decontaminated with Lactic Acid and Stored for Up to 126 Days . . . . . 128

Use of Oxyrase® Enzyme to Enhance Recovery o f Escherichia coli O157:H7from Culture Media and Ground Beef . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Breed Effects and Retained Heterosis for Growth, Carcass, and Meat Traits inAdvanced Generations of Composite Populations of Beef Cattle . . . . . . . . . . 134

Estimates of Genetic and Phenotypic Parameters for Carcass andMeat Traits of Beef Cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

INDEX OF KEY WORDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146BIOLOGICAL VARIABILITY AND STATISTICAL EVALUATION OF DATA . . . . . 147WEATHER DATA, 1992-1993 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

Contribution No. 94-373-S from the Kansas Agricultural Experiment Station.

iii


1

Cattlemen's Day 1994

LEVEL OF UREA IN HIGH GRAIN DIETS:FINISHING STEER PERFORMANCE

C. T. Milton and R. T. Brandt, Jr.

Summary

Eighty-eight medium-framed crossbredsteers (731 lb) were used to identify theoptimal level of urea in finishing diets forgrowth and carca ss traits. Diets contained nourea or .5, 1.0, or 1.5% urea (dry matterbasis) and no other supplemental protein.Feed efficiency and gain were improvedsubstantially by the first increment of urea(.5%), with little or no improvement fromsubsequent urea additions. Pooled acrosslevel, urea improved feed efficiency by 5.6%and gain by 8.9%, whereas dry matter intakedeclined 3.3% compared to controls. Re-gression analysis indicated that the optimallevel of urea for gain and feed efficiency was.91% of dietary dry matter. Dressing per-centage and hot carcass weight respondedquadratically, being higher for steers receiv-ing .5 or 1.0% urea. Fat thickness, yieldgrade, and KPH fat increased linearly withlevel of urea. Percentage choice carcassestended to increase, although no differences inmarbling score were observed with increasedurea. Because of increased carcass weightand finish, with no increase in loineye area,these data sugge st that adding urea increasedenergy utilization (diet digestibility) ratherthan metabolizable protein supp ly to the smallintestine.

(Key Words: Finishing Steers, Urea, Perfor-mance, Metabolizable Protein.)

Introduction

Current information concerning require-ments of finishing cattle for rumen degradableprotein and metabolizable protein is limited.In order to establish metabolizable or net

protein systems, a requirement for ruminaldegradable protein needs to be established.Urea is a common source of rumen degrad-able nitrogen in finishing diets and, therefore,our objective was to identif y the optimal levelof urea for performance and carcass traits offinishing yearling steers.

Experimental Procedures

Eighty-eight medium-framed crossbredsteers (731 lb) were received from Flint Hillsgrass in July 1993. A single initial weightwas taken following a 3-day equalized intakeperiod of prair ie hay and protein supplement.Steers were stratified into three weightblocks; implanted with Revalor®; andstepped up to the final ration without urea orcontaining .5, 1.0, or 1.5% urea (dry matterbasis). The step-up period of 14 days beganon the day initial weights were taken. Diets(Table 1) contained no supplemental proteinother than urea. Al l diets were formulated tocontain .7% Ca, .35% P, .7% K, 25 g/tonRumensin®, and 10 g/ton Tylosin®. Steerswere fed experimental diets for an average of131 days. The two largest weight blockswere slaughtered followi ng 119 days on feed,but the smallest weight block required anadditional 35 days on feed to reach a desir-able finished weight. Hot carcass weightsand a 62% dressing percent were used todetermine final weight for calculation of gainand feed efficiency. Steers were slaughteredat a commercial plant, and carcass data wereobtained following a 24-hour chill.

Results and Discussion

Dry matter intake responded cubically(P<.10) to the addition of urea, being lower


2

for steers supplemented with . 5 or 1.5% urea.The reduction in intake was probably associ-ated with an increased starch fermentationrate. Daily gain (P=.10) and feed efficiency(P<.02) responded quadratically to theaddition of urea. Both daily gain and feedefficiency were increased substantially by thefirst increment of ur ea (.5%), with little or noimprovement from subsequent urea additions.Pooled across level, urea supplementationimproved daily gain 5.6% and feed efficiency8.9% and reduced dry matter intake 3.3%compared to the control diet. As dietary ureaincreased, dressing percentage respondedquadratically (P<.01). A quadratic trend(P=.16) also was observed for hot carcassweights. Fat thickness (12th rib) increased(P<.04) and KPH fat tended (P=.14) toincrease linearly wit h level of urea. Loin eyearea and

incidence of liver abscesses were not affectedby dietary level of urea. Calculated yieldgrade increased linearly (P<.10) with level ofurea as a result of increased 12th rib fat andKPH fat. Percentage of carcasses gradingChoice tended (P=.17) to increase as dietarylevel of urea increased, although urea levelhad little effect on marbling scores. Predictedcrude protein requirements of steers in thisstudy (1.88 lb/day) were met by the controldiet. Improvements in performance andincreased carcass weight and finish, with noimprovement in loineye area, suggest thaturea enhanced energy utilization (diet digest-ibility) by the animal, rather than metaboliz-able protein supply to the small intestine. TheIowa State metabolizable protein systempredicted the urea fermentation potential forthe basal diet in this study to be 1.09%.Regression analysis (model Y= urea + urea )2

showed the optimal level of urea for gain(r =.31) and feed efficiency (r=.40) to be2 2

.91% of dietary dry matter .

Table 1. Diet Compositiona

Treatment (% Urea, dry matter basis)

Ingredient Control .5 1.0 1.5

Rolled corn 76.9 77.0 77.2 77.2Prairie hay 10.0 10.0 10.0 10.0Supplement 1 10.6 7.1 3.5 --b

Supplement 2 -- 3.4 6.8 10.3c

Molasses 2.5 2.5 2.5 2.5% Crude protein (dry matter basis) 7.7 9.0 10.3 11.6

Dry matter basis. Formulated to contain .7% Ca, .35% P, .7% K, 25 g/ton Rumensin, and 10a

g/ton Tylosin. Elemental sulfur was supplied to maintain a N:S ratio of 10:1 across treatments.Supplement supplied no urea.b

Supplement supplied 1.5% urea (dry matter basis) in 1.5 treatment.c


3

Table 2. Effect of Dietary Urea Level on Performance and Carcass Traits of Steers

Treatment (% Urea dry matter basis)

Item Control .5 1.0 1.5 SEM

No. pens 3 3 3 3

No. steers 22 22 22 22

Initial wt., lb 735 731 729 730 4.8

Final wt. , lb 1170 1193 1201 1184 12.6a

Daily feed , lb 24.37 23.12 24.00 23.56 .38b

Daily gain , lb 3.35 3.53 3.64 3.49 .09c

Feed/gain 7.29 6.54 6.62 6.76 .13d

Hot carcass wt., lb 726 740 745 734 7.8

Dressing % 62.04 63.13 63.09 62.11 .18e

KPH, % 1.58 1.73 1.84 2.00 .18

Loin eye area, in 13.5 13.7 13.4 13.4 .352

Fat 12th rib , in .31 .36 .46 .50 .05f

Yield grade 2.02 2.16 2.57 2.64 .25g

Marbling score 5.32 5.01 5.28 5.64 .32h

Pct Choice 41 41 59 68

Liver abscesses, % 5 5 0 5

Calculated as hot carcass weight/.62.a

Cubic (P<.10).b

Quadratic (P=.10).c

Quadratic (P<.02).d

Quadratic (P<.01).e

Linear (P<.04).f

Linear (P<.10).g

4= slight, 5= small, 6= modest.h


The authors express appreciation to Shannon Schneider for assistance in sample collection and1

laboratory analysis.

4


LEVEL OF UREA IN HIGH GRAIN DIETS:NUTRIENT DIGESTIBILITY, MICROBIAL PROTEIN

PRODUCTION, AND RUMEN METABOLISM 1

C. T. Milton and R. T. Brandt, Jr

Summary

Four ruminally and duodenally fistulatedsteers (1228 lb) were used in a 4 × 4 Latinsquare design to evaluate the effects ofdietary urea level on nutrient digestion,microbial protein production, and rumenmetabolism of steers fed a rolled corn dietwithout urea or with .5, 1.0, or 1.5% urea(dry matter basis) and no other supplementalprotein. Rumen digestibilities increased 33%for organic matter and 25% for starch withthe first increment (.5%) of urea, but little orno improvement occurred with subsequenturea additions. Apparent rumen nitrogendigestibility decreased linearly, whereas totaltract and true ruminal nitrogen digestibilityincreased linearly with increased urea.Duodenal nitrogen flow and m icrobial proteinproduction were not affected by treatment.Rumen pH decreased and tota l volatile fattyacids increased as dietary level of ureaincreased. Molar proportions of propionateincreased and butyrate decrease d linearly withthe addition of urea, suggesting increasedefficiency of rumen fermentation. RumenNH increased 63% following 1.0% urea3

addition to the diet. Urea improved ruminaldigestibility and increased efficiency offermentation but did not increase metabo-lizable protein to the small intestine.

(Key Words: Urea, Digestibility, Rumen,Steers.)

Introduction

Current information regarding therequirements by finishing steers for rumendegradable nitrogen and metabolizableprotein remains limited. In order to establishmetabolizable or net protein systems, rumendegradable protein requirements are needed.Urea is a common source of rumendegradable nitrogen in finishing diets.Therefore, the objective of this study was toevaluate the effects of di etary level of urea onnutrient digestion, microbial proteinproduction, and rumen metabolism.


Four ruminally and duodenally fistulatedcrossbred steers (1228 lb) were used in a 4 ×4 Latin square design t o evaluate the effectsof dietary urea level on nutrient digestibilityand ruminal metabolism. Diets (Table 1)contained no urea or .5, 1.0, or 1.5% urea(dry matter basis) and no other supplementalprotein. Steers were fed ad libitum twicedaily. Chromic oxide was used as anindigestible flow marker. Each periodconsisted of a 10-day die t adaptation and a 4-day sample collection period. During thecollection period, duodenal digesta and fecalgrab samples were collected four times dailyto determine ruminal and total tractdigestibilities of organic matter, starch, andnitrogen. Rumen fluid was collected at 3, 6,9, and 12 hours after the a.m. feeding andanalyzed for pH, volatile fatty acids, andammonia. Rumen contents were harvested


5

twice daily for 2 days to determine microbialprotein production.


Dry matter intake as a percent of bodyweight responded cubically to the addition ofurea (Table 2). Rumina l organic matter andstarch digestibilities tended (P=.23) torespond quadratically to the addition of urea.Both ruminal organic matter and starch wereimproved by the first increment of urea(.5%), with little or no improvement bysubsequent additions. Pooled across level,urea increased ruminal digestibility of organicmatter by 26% and starch by 25%, comparedto the control diet. Average total tractdigestibilities of organic matter were 76%,87% for starch and were similar (P>.25)among treatments. Apparent rumen nitrogendigestibility increased (P<.0 7) linearly as levelof urea increased. Nitrogen flowing from therumen with the control diet was 182% ofnitrogen intake, which indicates that a vastamount of nitrogen recycling was occurring.Total tract (P<.02) and true ruminal nitrogen(P<.10) digestibilities increased linearly asdietary level of urea increased. Duodenalammonia nitrogen flow tended (P=.16) torespond quadratically to urea level.Duodenal nitrogen flow, microbial proteinproduction, and microbial efficiency (g ofmicrobial N/100g of organic

matter fermented) were not affected (P>.24)by treatment. Rumen pH decreased (P<.01)and total volatile fatty acid concentrationincreased (P<.01) linearly with increasingurea, suggesting that supplemental ureaenhanced organic matter fermenta tion. Molarproportion of propionate tended (P=.11) toincrease, whereas that of butyrate decreased(P<.01) linearly with increasing urea,suggesting that fermentation efficiency wasincreased. Molar percent acetate respondedcubically (P<.01) to the addition of urea. Theincreased molar percentage of acetate withthe .5% urea diet was responsible for most ofthe cubic effect; other treatments varied little.Acetate:propionate ratios were not affectedby dietary urea level. Rumen NH concen-3tration responded cubically (P<.01) to ureaadditions. Little increase was observed withthe first increment of urea (.5%); however,1.0% urea increased rumen NH 63%, with3little further increase at 1.5%. The additionof urea improved rumen digestibility oforganic matter and starch, increased nitrogendigestibility, and enhanced efficiency of ru-men fermentation but did not increase theamount of microbial protein available to theanimal. These results suggest that ureaaddition improved energy utilization by theanimal but did not improve metabolizableprotein supply to the smal l intestine. Levelsof urea near .5% of the diet appear to besufficient for optimal rumen digestibility andfermentation efficiency.

Table 1. Diet Compositiona

Treatment (% Urea, dry matter basis)Ingredient Control .5 1.0 1.5

Rolled corn 76.9 77.0 77.2 77.2Prairie hay 10.0 10.0 10.0 10.0Supplement 1 10.6 7.1 3.5 --b

Supplement 2 -- 3.4 6.8 10.3c

Molasses 2.5 2.5 2.5 2.5% Crude protein (dry matter basis) 7.7 9.0 10.3 11.6

Dry matter basis. Formulated to supply .7% Ca, .35% P, .7% K, 25 g/ton Rumensin, and 10a

g/ton Tylosin. Elemental sulfur was supplied to maintain N:S ratio of 10:1 for all diets.Supplement supplied no urea . Supplement supplied 1.5% dietary urea (dry matter basis) inb c

1.5 treatment.


6

Table 2. Effect of Urea Level on Nutrient Digestibility, Microbial Protein Production andRumen Metabolism

Treatment (% Urea, dry matter basis) Item Control .5 1.0 1.5 SEM

Dry matter intake , % BW 2.52 2.59 2.15 2.43 .12a

Nitrogen intake, g/d 171 205 189 234 9.27

Apparent rumen digestibility, % of intake

Organic matter 25.3 43.2 36.9 34.3 7.04

Starch 47.1 64.6 59.2 63.7 7.48

Nitrogen -82.9 -28.1 -37.3 -17.9 11.4b

True rumen digestibility, % of intake

Organic matter 45.6 57.2 55.8 51.6 7.49

Nitrogen 3.7 32.9 33.4 46.7 14.8b

Total tract digestibility, % of intake

Organic matter 74.9 73.9 82.5 75.2 3.74

Starch 84.8 85.2 93.5 87.2 3.80

Nitrogen 55.9 58.4 70.8 67.2 4.40c

Duodenal N flow, g/d 321 264 267 291 27.2

Microbial N flow, g/d 146 125 141 153 14.01

Duodenal NH -N, g/d 17.6 22.4 29.2 19.6 4.513

Microbial efficiency 2.93 1.75 2.38 4.08 1.13d

Rumen pH 6.00 6.06 5.81 5.74 .08e

Rumen NH , mM 2.16 3.07 8.40 9.13 .693f

Total VFA , mM 113 109 127 133 4.22e

Acetate, molar % 44.7 47.1 43.1 44.8 .88

Propionate, molar % 27.3 28.0 29.6 30.3 1.46

Acetate:Propionate ratio 1.78 1.92 1.61 1.68 .14

Butyrate , molar % 16.4 12.3 11.2 9.9 1.21e

Cubic (P<.07).a

Linear (P<.10).b

Linear (P<.02).c

Grams of microbial N/100g of organic matter truly fermented in the rumen.d

Linear (P<.01).e

Cubic (P<.01).f


7


SOURCE AND LEVEL OF CRUDE PROTEIN FORIMPLANTED FINISHING STEERS

C. T. Milton and R. T. Brandt, Jr.

Summary

One hundred medium-framed, crossbredsteers (738 lb) were used to compare non-protein nitrogen to natural protein supple-mentation of finishing diets for implantedsteers. Diets were formulate d to contain 11.5or 13.5% crude protein and weresupplemented with either urea or soybeanmeal. A fifth treatment of cottonseed mealsupplementation (13.5% dietary crudeprotein) was added to evaluate differencesbetween natural sources of rumen degradableprotein. Steers were implanted withRevalor® and fed for 132 days. During thefirst 70 days, daily gain and feed efficiencywere improved 8.8 and 6.1%, respectively,for steers supplemented with soybean meal vsurea. No difference was observed withprotein level. For the entire feeding period,soybean meal increased dry matter intake3.8% compared to urea. Protein source andlevel interacted on daily gain. Increasingdietary protein from 11.5 to 13.5% decreasedgain by urea-fed steers 8%, whereasincreasing dietary protein fr om 11.5 to 13.5%increased gain 6.1% for steers supplementedwith soybean meal. Soybean meal improvedfeed efficiency 7.6% compared to urea.Protein level had no effect on feed efficiency.Steers supplemented with soybean meal hadlarger loineye areas than those supplementedwith urea. Carcass finish, percentage of car-casses grading Choice, and yield grade werenot affected by treatment . Performance andcarcass traits of steers fed cottonseed mealwere similar to those of steers fed soybeanmeal. We conclude that urea cannot meet themetabolizable protein

needs of implanted finishing steers. Cot-tonseed meal did not differ from soybeanmeal as a protein source in this study.

(Key Words: Finishing Steers, Urea,Soybean Meal, Performance.)

Introduction

Growth promotants, especially thecombination of estradiol and trenboloneacetate, have the potential to alter nutrientrequirements in feedlot steers. Currentinformation concerning requirements ofrapidly growing feedlot steers for rumendegradable and metabolizable protein islimited. Soybean meal and urea are twocommonly used sources of protei n in finishingdiets. The usefulness of urea is limited to theamount that provides sufficient rumenammonia to maximize microbial proteinproduction and(or) rumen organic matterdigestion. Other research presented in thispublication suggests that, although ureasupplementation increases rumen organicmatter digestion, it does not enhance proteinflow to the small intestine. Conversely,soybean meal contains a degradable proteinfraction to supply ammonia, amino acids,peptides, or other growth factors to rumenmicrobes, as well as an escape fraction toincrease true protein reaching the smallintestine. Therefore, soybean meal should bebetter able to increase the supply ofmetabolizable protein to rapidly growingsteers. Our objective was to evaluate twolevels of soybean meal and urea onperformance and carcass traits of implantedfinishing steers.


8


One hundred medium-framed crossbredsteers (738 lb) were stratified by weight intoone of four blocks. Within each block, steerswere allocated to one of five pens in a 2×2+1factorially arranged experiment. Diets (Table1) contained supplemental protein from ureaor soybean meal and were formulated toprovide 11.5 or 13.5% (dry matter basis)crude protein. A cottonseed meal diet,formulated to provide 13.5% dietary crudeprotein, was used as an additional treatmentto determine differences between the twonatural sources of rumen degradable protein.All diets were formulated (dry matter basis)to contain .7% Ca, .35% P, .7% K, 25 g/tonRumensin®, and 10 g/ton Tylosin®. Initialweights were the averages of two consecu-tive early morning weights. Steers wereimplanted with Revalor and stepped up tofinal rations in 14 days. Steers were fed theexperimental diets for 132 days. Hot carcassweights adjusted by a 62% dressing percentwere used as final weights fo r calculation ofgain and feed efficiency. Steers wereslaughtered at a commercial plant withcarcass data being obtained following a 24-hour chill. The statistical analysis allowedcomparisons of: 1) level of crude protein, 2)source of crude protein, 3) interactionbetween level and source of crude protein,and 4) soybean meal vs cottonseed meal at13.5% dietary protein.


During the first 70 days, daily gain(P<.05) and feed efficiency (P<.10) wereimproved 8.8 and 6.1%, respectively, forsteers supplemented with soybean meal vsurea (Table 2). Despite rapid gains (3.6 to4.0 lb/day), increasing dietary protein above11.5% did not improve daily gain or feedefficiency.

Steers supplemented with soybean mealconsumed 3.8% more feed (P=.23 ) over theentire feeding period than those supple-mented with urea. A level by sourceinteraction (P<.05) was observed for dailygain. Daily gain by steers fed urea was

decreased 8.0% by increasing supplementa-tion to 13.5% dietary crude protein, whereasgain by steers fed soybean meal increased6.1% when crude protein levels wereincreased from 11.5 to 13.5%. Steerssupplemented with soybean meal were 7.6%more efficient (P<.03) than thosesupplemented with urea; feed efficiency wasnot affected by dietary level of crude protein. The improvement in performance fromsoybean meal probably was due to improvedfeed intake, increased metabolizable proteinsupply, and(or) improvements in fermentationfrom the provision of rumen degradableamino acids and peptides. Dietary crudeprotein level and source interacted (P<.05) toaffect hot carcass weight. As dietary crudeprotein level from urea increased from 11.5to 13.5%, hot carcass weight decreased2.5%, whereas increasing dietary crudeprotein level from 11.5 to 13.5% withsoybean meal increased hot carcass weight2.4%. Compared to urea, soybean mealsupplementation increased (P<.10) loineyearea, but no effect of dietary protein levelwas observed. These data suggest that urea-fed steers were deficient in metabolizableprotein and that this was at least partiallycorrected by supplementing with soybeanmeal. Dressing percentage, fat thickness(12th rib), marbling score, yield grade, andpercentage of carcasses grading choice werenot affected by treatment.

Results from previous research suggestthat urea supplementation serves to enhanceorganic matter fermentation in the rumen,with little or no increase in metabolizableprotein supply to the animal. Improvementsin performance and increased carcass weightsand loineye areas, with little increase incarcass finish, suggest that supplementinghigh grain diets with soybean meal increasesthe total supply of metabolizable protein tothe animal. This may be mediated viaincreased feed intake, increased microbialprotein production, or escape of soybeanmeal protein to the small intestine. Steers fedcottonseed meal had performan ce and carcasstraits similar to those of steers fed soybeanmeal. Whether benefits from soybean andcottonseed meals result from the degradable


9

or escape fractions, or a combination of thetwo, is unclear. However, nonproteinnitrogen evidently cannot meet the metaboliz-able protein requirement of rapidly growingsteers.

Feed cost of gain and economic return tolevel and source of crude protein arepresented in Table 3. Relative to urea, rationcosts were increased when soybean meal orcottonseed meal was fed. However, becauseof improved daily gain and feed efficiency,cost of gain was similar and economic returnswere increased when soybean meal orcottonseed meal was fed.

Table 1. Diet Compositio n (Dry Matter Basis)

Treatmenta

Item 11.5/Urea 13.5/Urea 11.5/SBM 13.5/SBM13.5/CSM

Rolled corn 85.4 84.6 80.6 76.2 73.1

Prairie hay 8.0 8.0 8.0 8.0 8.0

Soybean meal -- -- 6.2 10.7 --b

Cottonseed meal -- -- -- -- 13.7b

Urea .93 1.58 -- -- --

Vitamins, minerals, and

additives 3.2 3.3 2.7 2.6 2.7c

Molasses 2.5 2.5 2.5 2.5 2.5

Dietary treatments (% crude pr otein/source). SBM = soybean meal; CSM = cottonseed meal.a

Soybean meal and cottonseed meal contained (as-fed basis) 48 and 41% crude protein,b

respectively.

To provide dietary levels of 1500 I U/lb Vitamin A, 20 IU/lb Vitamin E, .7% Ca, .35% P, .7%c

K, 25 g/ton Rumensin®, and 10 g/ton Tylosin®.


10

Table 2. Effect of Level and Source of Crude Protein on Performance and Carcass Traits ofImplanted Finishing Steers

Treatmenta

Item 11.5/Urea 13.5/Urea 11.5/SBM 13.5/SBM 13.5/CSMSEM

No. pens 4 4 4 4 4No. steers 20 20 20 20 20Initial wt, lb 736 740 738 739 7391.8Final wt , lb 1147 1118 1168 1197 1198 12.8b

Day 0-70Daily feed, lb 21.76 21.28 22.08 22.13 23.39

.58Daily gain , lb 3.64 3.61 3.89 4.07 3.95c

.14Feed/gain 6.01 5.89 5.73 5.46 5.95d,e

.21Day 0-132

Daily feed, lb 21.66 20.56 21.78 22.09 22.80.65

Daily gain , lb 3.11 2.86 3.25 3.46 3.47 .09f h i hj j j

Feed/gain 6.98 7.19 6.72 6.37 6.59 .21c,e

Carcass TraitsHot carcass wt , lb 711 693 724 742 743 7.9f h hi hj j j

Dressing % 62.0 60.4 61.3 61.2 61.9 .54Fat 12th rib, in .46 .41 .44 .49 .48 .03KPH, % 2.43 2.30 2.38 2.42 2.48 .08Loineye area , sq in 13.9 13.9 14.3 14.9 15.2 .37d

Marbling score 5.21 5.04 5.17 5.31 5.17 .16g

Yield grade 2.38 2.16 2.26 2.24 2.16 .13Percent choice 70 70 85 85 80

Dietary treatments (% crude protein/source) SBM = soybean meal; CSM = cottonseed meal.a

Final wt = Hot carcass wt÷.62.b

Urea vs soybean meal (P<.05).c

Urea vs soybean meal (P<.10).d

Feed/gain was analyzed as gain/feed and reported as the reciprocal. e

Crude protein level by protein source interaction (P<.05).f

4 = slight, 5 = small, 6 = modest.g

Means in a row lacking a common superscript differ (P<.10).hij


11

Table 3. Effect of Level and Source of Crude P rotein on Economic Return in Implanted FinishingSteers

Treatment

Item 11.5/Urea 13.5/Urea 11.5/SBM 13.5/SBM 13.5/CSM

Ration cost, $/ton 103.20 104.00 109.52 114.66 115.74a

Ration cost, $/head 148.21 141.12 157.43 167.17 174.17Yardage and interest 46.20 46.20 46.20 46.20 46.20b

Feed cost of gain, $/lb .360 .373 .368 .365 .381Cost of gain. $/lb .472 .495 .474 .466 .480

Economic return, live basisc

Income, $/head 837.31 816.14 852.64 873.81 874.54Cost, $/head 822.05 816.99 831.27 841.01 848.01d

Return, $/head 15.26 4.15 21.37 32.80 26.53

Urea = $220/ton, soybean meal = $220/ton, cottonseed meal = $205/ton.a

Calculated $.35 /head/day.b

Cash price $73.00 per cwt.c

Initial cost $85.00 per cwt.d


Department of Clinical Sciences.1

12


D- VS L-METHIONINE UTILIZATION BYGROWING STEERS

C. G. Campbell, E. C. Titgemeyer, and G. St. Jean1

Summary

Increasing the amino acid supply to thesmall intestine of growing cattle can increaseperformance, if specific amino acids arelimiting. Although this can be accomplishedby feeding rumen undegradable protein, amore economical approach may be supple-menting only those amino acids that actuallylimit performance, but in a form that willbypass the rumen. Methionine (MET) isthought to be a limiting amino acid forgrowing cattle. DL-MET, a 50 :50 mixture ofnatural methionine (L-MET) and theunnatural optical isomer (D-MET) is usedwidely in monogastric rations. Ruminallyprotected DL-methionine is also available forcattle; however, little information is availableabout its utilization by growing steers. Westudied the efficiency of utilization of D- vsL-MET by growing steers by measuringnitrogen retention of steers postruminallysupplemented with graded levels of D- or L-MET. Nitrogen retention increased linearlyin response to infusion of both L-MET andD-MET, with similar responses for the twoisomers. The efficiency of utilization of D-MET relative to L-MET was estimated to be95.5%. In conclusion, D-MET was similar toL-MET in increasing nitrogen retention ofgrowing steers.

(Key Words: Methionine, Growing Steers,Nitrogen Retention.)

Introduction

Current research has looked at rumenundegradable protein sources as ways toincrease the amount of amino acids availableto the small intestine of growing cattle. Anincrease in amino acid availability shouldresult in greater protein deposition bygrowing cattle, if specific amino acids limitperformance. Alternatively, supplying onlythose limiting amino acids could be a moreeconomical means of incr easing performance.The swine and poultry industries currentlysupplement methionine (MET) as DL-MET,a 50:50 mixture of the natural L-MET andthe unnatural D-optical isomer. Monogastricanimals can convert D-MET to L-MET fairlyefficiently. However, despite the fact thatruminally protected DL-MET is nowcommercially available for cattle, there islittle information regarding the utilization ofthe D-MET by ruminant animals. Ourobjective was to determine whether D-METwas as efficiently utilized as L-MET by grow-ing cattle.


Five ruminally cannulated Holstein steersaveraging 396 lb were utilized in a 5 × 5Latin square and kept in individualmetabolism crates in an environmentallycontrolled room. Each period lasted 6 days;the first 2 days for adaptation to treatmentsand the last 4 days for total collection offeces and urine to measure nit rogen retention.Treatments were no MET (control) orcontinuous abomasal infusion of 2 g/day of


13

L-MET, 4 g/day of L-MET, 2 g/day of D-MET, or 4 g/day of D-M ET. To be sure thatonly MET limited steer performance, a dietlow in ruminal undegradable protein was fed.The diet contained 84.7% soyhulls, 6.7%wheat straw, 8.2% mineral mix (minerals,vitamins, Bovatec, and molasses), and .5%urea and was fed twice daily at 6.6lb/head/day. Because of the restricted intake,150 g acetate, 150 g propionate, and 37.5 gbutyrate were infused daily and continuouslyinto the rumen to ensure that energy wouldnot limit performance. Dextrose also wasinfused into the abosmaum continuously at300 g/day to increase energy availability. Toensure that amino acids other th an methioninewould not limit nitrogen retention, 15 g of L-valine, 20 g of L-leucine, 15 g of L-isoleu-cine, 23.6 g of L-lysine, 7.4 g of L-histidine,15 g of L-arginine, 14.7 g of L-threonine, 25g of L-phenylalanine, 4.9 g of L-tryptophan,75 g of L-glutamate, and 25 g of glycinewere infused into the abomasum daily.


Nitrogen retention increased as theamount of infused MET increased (Table 1).This response was similar between D- and L-MET, with D-MET being 95.5% as efficientas L-MET. As expected, the

differences in nitrogen retention amongtreatments were due to changes in urinarynitrogen; no significant differences occurredin fecal nitrogen. A regression model, usedto estimate nitrogen retention from METsupplementation, showed nitrogen retention(g/day) equal to 19.2 + (1.81*D-MET) +(1.90*L-MET).

A major requirement of nitrogen in thebody is for muscle protein synthesis, so wewould expect skeletal muscle deposition toparallel as nitrogen retention. Previous workhas estimated nitrogen content of tissue gainat 3.26%. Using that value, each gram ofextra MET per day of treatment should leadto .25 lb of tissue, if all the nitrogen retainedwent for tissue protein gain, up to the pointwhere MET is no longer l imiting. These highlevels of potential protein deposition relativeto the small amount (4 and 2 g) of METdemonstrate the potential that exists forrumen-protected amino acids.

In conclusion, D-MET appears to be asefficient as L-MET in supporting nitrogenretention in growing steers. Ruminantsapparently convert D-MET to the L-isomeras efficiently as monogastrics. Therefore,growing cattle diets that utilize a ruminallyprotected form of DL-MET should respondas favorably as those postruminally supple-mented with L-MET.

Table 1. Effect of Postruminal Supplementation of D- or L-Methionine (MET) onNitrogen Retention of Growing Holstein Steers

L-MET D-MET

Nitrogen (g/d) Control 2 g 4 g 2 g 4 g SEM

Intake + infused 86.8 86.8 87.3 86.1 87.1 .6Fecal 24.1 24.5 25.1 24.7 25.5 .6Urinary 43.4 38.9 35.5 38.8 35.0 1.4ab

Retained 19.2 23.3 26.6 22.5 26.6 1.6ab

Linear effect of L-MET (P<.05).a

Linear effect of D-MET (P<.05).b


14


EFFECT OF RUMEN-ESCAPE PROTEIN LEVEL ONFEEDLOT PERFORMANCE AND CARCASS TRAITS OFIMPLANTED VS NONIMPLANTED YEARLING STEERS

C. D. Reinhardt and R. T. Brandt, Jr.

Summary

One hundred eighty yearling steers (743lb) were blocked by weight; implanted withSynovex® (S), Synovex plus Finaplix® (SF),or not implanted (C); and fed diets containing11.75% (L), 13.0% (M), or 14.25% (H)crude protein with all supplemental proteinabove 11.75% being supplied by corn glutenmeal and blood meal in a 50:50 ratio (crudeprotein basis). An addition al protein level fedto S and SF implanted cattle was H for thefirst 70 days on feed and L thereafter (H-L).Animals were reimplanted on day 70. Steerstreated with SF gained faster and moreefficiently than non-implanted cattle.Differences in protein level had no effect onfat deposition in control steers, but cattlereceiving SF and consuming M had moreback fat and kidney, pelvic, heart (KPH) fatthan those fed either H or L and also hadmore marbling than those fed H. Also, noapparent differences occurred between cattlefed M throughout the trial and those switchedfrom H to L at 70 days.

(Key Words: Estradiol, Trenbolone Acetate,Implants, Escape Protein, Protein Level.)

Introduction

Cattle receiving growth promotants,particularly trenbolone acetate (TBA), havegreatly enhanced rates of lean deposition,which may increase their demand for me-tabolizable protein above traditional levels ofsupplementation. The amount of proteinreaching the small intestine can be increasedby using high rumen-escape protein sourcessuch as blood meal and corn gluten meal,

while requirements for ruminally availablenitrogen are met with urea.


One-hundred eighty head of mixedcrossbred yearling steers were received offNorth Texas summer grass in September,1992. Cattle were dewormed, vaccinated,ear-tagged, and fed a 57% concentrate rationfor 28 days on a receiving study. The cattlewere weighed (October 13 and 14, 1992; avg743 lb); implanted with either Synovex-S (S),Synovex-S plus Finaplix (SF), or notimplanted (C); and stepped up onto a 12%roughage finishing ration (Table 1). Cattlealso were assigned to a diet containing either11.75%, 13%, or 14.25% cr ude protein. Thetwo higher protein levels were achieved witha 50:50 blend (crude protein basis) of bloodmeal and corn gluten meal (crude proteinbasis). An additional protein level assignmentfed to S and SF implanted cattle was H forthe first 70 days on feed and L thereafter (H-L). Cattle were reimplanted with theirrespective implants on day 70 and weighed at35-day intervals until finished. Final weightswere the averages of weights on 2 consecu-tive days (March 30 and 31, 1993). Hotcarcass weights were taken at slaughter, and12th rib fat thickness, ribeye area, KPHestimation, and marbling measurements weretaken after a 24-hour chill.


Rate of gain was slower than expectedfor this size and type of cattle, even thoughintake was near expected levels across alltreatments, probably because of severalperiods of freezing rain. These low gains


15

may have limited the response to bypassprotein supplementation.

Final weights in this study were hotcarcass weights adjusted to an averagedressing percent of 61.1. Cattle implantedwith SF gained faster (P<.05; Table 2) andmore efficiently than nonimplanted steers.Steers implanted with SF also had heaviercarcasses and greater ribeye areas (P<.05).

Interactions (P<.10) between implant andprotein level affected dressing percent, fatthickness, KPH fat, and marbling. Steersreceiving SF and consuming M had slightlylower dressing percentages, which may havebeen a function of slightly

higher intake. Within the control group, nodifferences occurred in fat deposition, butwithin the SF treatment, steers consuming Mhad more back and KPH fat than thoseconsuming either L or H (P<.10) and slightlymore marbling than steers consuming H(P=.14).

Implants have been shown to be mosteffective in cattle with superior genetics forgrowth and in cattle on high energy intakes.Feedlot trials have shown benefits of escapeprotein supplementation, with the greatestadvantages in fast gaining cattle. Althoughthe SF-treated steers outperformed controls,faster gains across all treatments would beexpected during milder weather. For thisreason, further research is warranted oncrude protein level and escape proteinsupplementation for implanted feedlot cattle.

Table 1. Composition of Experimental Diet

Ingredient Low Medium High

---------------------- % of Dry Matter ----------------------

Corn 80.47 78.64 76.80

Corn silage 12.0 12.0 12.0

Supplement 7.53 7.54 7.53a

Blood meal — .79 1.57

Corn gluten meal — 1.04 2.08

Crude protein 11.75 12.99 14.24

aProvided .86% dietary urea. Supple ments were formulated so that diets contained (dry basis)

.7% Ca, .35% P, .7% K, .35% salt, and 100 ppm Zn.


16

Table 2. Effects of Implant and Protein Level on Steer Performancea

Control Synovex® + Finaplix® Synovex®

Item Low Med High Low Med High High-Low Med High-Low

Daily gain, lb 2.50 2.16 2.17 2.54 2.54 2.37 2.71 2.38 2.38bc

Daily feed, lb 20.28 20.45 20.15 20.57 20.84 20.12 19.98 20.42 20.67

Gain:Feed .119 .103 .103 .120 .118 .115 .131 .115 .115b

Dressing % 63.0 61.3 59.5 60.5 58.6 60.4 62.7 61.9 61.8d e ef ef ef f ef ef ef ef

Carcass, lb 721 687 687 724 726 709 741 709 708bc

Back fat, in .44 .46 .47 .45 .58 .39 .46 .40 .47d e ef ef e f e ef e ef

KPH, % 2.61 2.63 2.64 2.37 2.70 2.38 2.43 2.41 2.43d fgh gh gh e h e efg ef efg

REA, sq. in 12.0 11.8 11.9 12.7 13.0 12.4 12.6 12.6 12.1b

Yield grade 3.03 3.03 3.03 2.80 3.09 2.66 2.90 2.64 2.99

Marbling 4.10 4.11 4.14 3.69 3.88 3.52 3.65 3.68 3.97di g g g ef efg e ef ef fg

Choice, % 35 50 40 25 30 20 25 30 35

aLow=11.75% crude protein, Med=13% crude protein, High=14.25% crude protein.

Synovex + Finaplix vs. Control (P<.05). Adjusted to common dressing % of 61.1.b

Low vs. High (P<.10).c

Protein × Implant interaction (P<.10).d

Within a row differ (P<.10).e,f,g,h

3=Slight , 4=Small .i 0 0


Professor of Animal, Dairy, and Veterinary Science, Clemson University, Clemson, SC.1

17


PAYOUT CHARACTERISTICS OF ANABOLIC AGENTSFROM SYNOVEX®, FINAPLIX®, AND REVALOR® IMPLANTS

IN FINISHING YEARLING STEERS

P. S. Hickman, R. T. Brandt, Jr., D. M. Henrick s ,1

J. S. Stevenson, and J. E. Minton

Summary

Forty, individually fed, yearling steers(750 lbs) were used to measure payoutcharacteristics of different tre nbolone acetate-containing implants and to correlate thosecharacteristics to growth response.Treatments were 1) control, 2) Synovex-S®,3) Finaplix-S®, 4) Synovex® plus Finaplix,and 5) Revalor®. Steers were fed a 12%crude protein, corn-based, finishing diet for112 days. Compared to Revalor, which hada fairly constant payout over time, thecombination of Synovex plus Finaplixresulted in higher blood levels of estradioland trenbolone acetate (TBA) up to 56 days,followed by a relatively rapid declin e to 112days. Despite elevated levels of TBA at 112days for all TBA-containing implants andelevated estradiol at 112 days from Revalorsteers, implants did not improve performancein the final 28 days before slaughter. Short(less than 120 days) feeding periods mayfavor implants that increase blood levels ofanabolics for shorter (56-84 day) periods.Data for plasma urea nitrogen were inter-preted to indicate that 12% cr ude protein wasadequate for yearling steers gaining approx-imately 3.5 lbs per day.

(Key Words: Trenbolone Acetate, Estradiol,Serum Hormones, Feedlot.)

Introduction

Anabolic implants are proven, safe, andeffective management tools to enhanceprofitability for cattle feeders. In order to

optimize performance and maximize return,implant programs should be custom designedfor each pen of cattle, based on cattle type,projected days on feed, and market orcontract specifications for finished cattle.

Research has shown that, in beef cattle,maximal response to trenbolone acetate(TBA) has generally been achieved when itwas administered in combination with anestrogenic implant used once and admin-istered as the terminal implant in the sched-ule. Recent K-State research indicated thatcalf-fed Holstein steer performance isenhanced with multiple TBA implants,although carcass quality grade may bereduced. This places added importance onknowing release rates from TBA-containingimplants, in order to maximize performanceand minimize negative effects on carcassquality. Estrogenic implants also may reducecarcass quality if administered too close toslaughter (less than 60-65 days remaining onfeed). Two TBA-containing implants arecommercially available. Finaplix-S contains140 mg TBA in a lactose-carrie r , and RevalorS contains 120 mg TBA plus 24 mg estradiolin a cholesterol-based implant. Synovex-Scontains 20 mg estradiol benzoate and 200mg progesterone. We measured payoutcharacteristics of these implants and corre-sponding performance of finishing yearlingsteers.


18


Forty, crossbred, yearling, beef steers(750 lbs) were penned individually and fed arolled corn finishing diet (10% roughage, drybasis) that contained 12% crude protein.Steers had been previously implanted withSynovex-S and backgrounded on corn silagefor 90 days. Previous implant s were removed14 days before this study began.

Eight steers were assigned to each of fiveimplant treatments: 1) Control (no implant),2) Synovex-S only (SYN), 3) Finaplix-S only(FIN), 4) Synovex plus Finaplix usedtogether (SYN + FIN), and 5) Revalor(REV). Blood samples were obtained twicedaily (30 minutes apart, before the morningfeeding) on days 0, 14, 28, 42, 56, 84, and112. Serum was analyzed for estradiol,trenbolone acetate, and growth hormone.Plasma was analyzed for urea nitrogen. Thetrial was conducted for 112 days (May 1 toAugust 21, 1992). Steers then wereslaughtered, and carcass characteristics weremeasured.


As expected, serum trenbolone acetate(TBA) concentrations were essentially zerofor control and SYN steers and lower(P<.05) than those for t he other treatments atall sampling times (Figure 1). Serum concen-trations of TBA were higher (P<.10) in steersimplanted with Finaplix vs Revalor for thefirst 42-56 days of the study, then declined.At 84 days, TBA levels were similar forsteers implanted with Finapl ix or Revalor, butwere higher (P<.10) at 112 days for Revalorsteers. Thus, TBA in Revalor apparentlypays out at a fairly constant rate (at least to112 days), whereas payout from Finaplix ischaracterized by a more rapid release for thefirst 42-56 days, followed by a decline.

Changes in serum estradiol concentra-tions (Figure 2), although somewhat morevariable, show similar trends. Estradiol inRevalor-implanted steers remained relativelyconstant throughout the 112 days. Con-versely, estradiol was elevated for SYN+FIN

steers for approximately 84 days, thendropped rapidly. Serum estradiol levels werehigher for SYN+FIN vs SYN steersthroughout the first 84 days of the study.Although the reason for t his synergistic effectis not entirely clear, we know that significantamounts of TBA can be converted toestradiol in the body. A lternatively, TBA candisplace estradiol from receptor sites, thusincreasing circulating estradiol concentration.

In our study, implant type did not affectserum growth hormone or plasma ureaconcentrations. Generally, implantation withestradiol has been associated with increasedblood concentrations of growth hormone,although most of that work has been donewith younger animals. These data indicatethat some factor other than increased growthhormone is responsible f or growth promotionby anabolic implants. Time on feed hadsignificant effects on growth hormone andplasma urea nitrogen (Figure 3). Growthhormone concentration decreased linearly(P<.01) with time on feed, as animalsapproached physiological maturity. Plasmaurea nitrogen increased (P<.01) with time onfeed. This might be interpreted to indicatethat 12% crude protein progressivelyexceeded the protein requirement of thesteers during the finishing period, becauseelevated plasma urea is associated withprotein wastage. Further, the lack of animplant effect or implant × time interactionsuggests that 12% crude protein (50%soybean meal N:50% urea N) met orexceeded the protein requirements forimplanted steers in this study. Compared tononimplanted control steers, feed efficiencywas improved 16.8, 8.1, 28.7 and 16.8% forsteers implanted with Synovex, Finaplix,Synovex plus Finaplix, and Revalor, re-spectively. No deleteriou s carcass traits wereseen for any implant treatment.

Ears were collected at slaughter andevaluated for abscesses. Large implant-siteabscesses were noted for 2 of 16 steersimplanted with Synovex, 2 of 16 steersimplanted with Finaplix, and 1 of 8 steersimplanted with Revalor. Blood levels ofestradiol and TBA for steers with abscessed


implant sites did not deviate significantlyfrom treatment averages.

Regardless of mechanisms involved,elevated serum concentrations of hormonesgenerally correlated well with period dailygains by the steers (Figure 4), particularly forSYN+FIN steers. No gain response from anyimplant was seen in the last 28 days, despiteelevated serum levels of

TBA (REV, SYN+FIN, FIN) and estradiol(REV). Lack of an implant response as cattleapproach slaughter has been observed inother Kansas State research. This suggeststhat finishing weight is nearing matureweight, and little response should beexpected from anabolic agents. The impli-cation is that, for yearlings fed for 120 days,the time frame for an implant response maybe only about 90-100 days. A more rapid,shorter-lived payout of anabolic agents maypromote faster, more efficient growth in thisinstance.

Figure 1. Serum Concentrations of Trenbolone Acetate

1 9


Figure 2. Serum Concentrations of Estradiol (E2)

Figure 3. Plasma Urea Nitrogen (PUN) and Growth Hormone (GH) in Implanted Steers

Figure 4. Average Daily Gain (ADG) by Implanted Steers

2 0


21


ROUGHAGE LEVELS AND COMPARISON OFMIXED RATIONS VS SELF-FEEDERS IN WHOLE

SHELLED CORN FINISHING PROGRAMS

C. T. Milton, R. T. Brandt, Jr., and S. A. Shuey

Summary

Two trials were conducted to evaluateroughage levels in whole shelled-cornfinishing diets and to compare use of self-feeders to a total mixed ration in a wholecorn program. In trial 1, steers were fedwhole corn diets alone or with 4 or 8%roughage or a rolled corn diet with 8%roughage. Increasing the roughage levelincreased dry matter in take, feed required perunit of gain, and carcass weight and finish,and reduced the incidence of liver abscesses.Despite better feed eff iciency and lower costsof gain, reducing the dietary roughage levelreduced profitability because of lighterslaughter weights. In trial 2, feeding 4% vsno roughage in a whole-corn finishingprogram increased dry matter intake andtended to increase rate of gain by finishingheifers. No performance benefit resultedfrom feeding a total mixed ration vs usingself-feeders and providing chopped hay in afeed bunk.

Feeding very little or no roughage inwhole corn diets can improve feed efficiencyand reduce cost of gain. However, these ad-vantages can be outweighed by potentiallylower slaughter weights and increasedmetabolic problems (acidosis, bloat, liverabscesses).

(Key Words: Whole Shelled Corn, Rough-age Level, Feedlot.)

Introduction

Whole shelled corn has been successfullyused in cattle finishing programs for years.Whole corn diets are assumed to need lower

amounts of roughage, because whole corn isthought to have some roughage value itself.However, little information exists for optimalroughage levels in whole corn rations.Further, although unproven, it is assumedthat feeding a total mixed ration is preferableto using self-feeders in whole corn programsbecause roughage is supplied at the sametime as the concentrate. Therefore, twostudies were conducted to 1) identify theoptimal roughage level for whole-cornfinishing diets, and 2) to compare use of awhole corn ration (with or without roughage)in self-feeders to a total mixed ration.


Trial 1. Ninety-two Angus crossbredsteers (633 lbs) were allotted to one of threeweight blocks and then assigned to one offour pens within each block. Treatmentswere whole shelled corn (WSC) diets withoutroughage or with 4 or 8% roughage (drybasis). A fourth treatment, dry rolled cornplus 8% roughage, served as a positivecontrol.

In addition to the appropriate roughagelevel, all diets contained (dry basis) 3%molasses and 6.5% of a pelleted proteinsupplement. Diets were formulated tocontain 12.25% crude protein, .70% Ca,.35% P, .7% K, and 100 ppm Zn. Dietscontained monensin (27 g/ ton) but no tylosin.Steers had been vaccinated, dewormed, andimplanted with Revalor-S®. The trial wasconducted from January 2 to June 15, 1993(166 days). Slaughter and carcass data wereobtained at the conclusion of the study.


22

Trial 2. Sixty-three heifer mates (715lbs) to the steers in Trial 1 were used toevaluate the effects of offering roughage tocattle finished on whole corn and pelletedprotein supplement in self-feeders and tocompare these systems to a total mixedration. Treatments were: 1) a total mixedration with 4% alfalfa hay (dry basis), 2) awhole corn plus pelleted protein supplementoffered ad libitum from self-feeders, and 3)treatment 2 plus 4% hay offered in a feedbunk.

Diets and supplements were similar tothose in Trial 1, except mo lasses was reducedto .75% of the dry ration to fac i litate handlingin the self-feeders. Corn r eplaced molasses inthese rations. Heifers were vaccinated,dewormed, and implanted with Finaplix-Hand Ralgro. The study was conducted fromApril 20 to July 19, 1993 (90 days). Dailyhay fed in treatment 3 was based on theprevious day's hay consumption by heifers intreatment 1 and was offered in the morning.Three pen replicates were us ed per treatment.


Trial 1. Although adding roughage up to8% of the diet dry matter linearly increased(P<.05) total intake by steers fed wholeshelled corn (Table 1), corn intake remainedconstant. Steers fed dry rolled corn diets(8% roughage) consumed 10.5% more(P=.13) dry matter and corn than steers fedWSC with 8% roughage. The latterobservation is consistent with other researchand suggests that chewing efficiency (particlesize reduction) may limit intake of whole vsprocessed corn.

Daily gain tended (P=.2) to increase withincreased roughage level. Increased rough-age levels resulted in a line ar increase (P<.10)in feed required per unit of gain, as well as alinear reduction (P<.10) in net energyconcentration of the diet. The

latter, calculated from performance, wasexpected because adding roughage dilutesthe net energy concentrations of high-graindiets.

The tendency for increased weight gainwith increased roughage level translated intoheavier, more highly finishe d carcasses (Table2). Hot carcass weight and degree ofmarbling (P<.10) and backfat thickness(P<.05) increased as roughage level in-creased. The incidence of li ver abscesses wasgreatest (P=.11) without roughage andtended to decline as roughage level wasincreased. The severity of liver abscesseswas also greatest without roughage andtended to decline linearly (P<.2) with addedroughage.

Adding roughage to whole shelled corndiets not only reduced feed efficiency, butincreased both cost of gain and calculatedselling breakeven price for the steers (Table2). However, because of more weight sold(live or carcass) from the 8% roughagetreatments, net returns were not different.Therefore, it is important to remember thatreducing cost of gain does not alwaystranslate into increased profitability.

Trial 2. Similar to trial 1, heifers fedroughage, whether in a complete mixedration or separately in the feed bunk, con-sumed more feed (P=.06) and gained 10.6%faster (P=.19) than heifers fed from self-feeders alone (Table 2). The differenceswould likely have been greater had 8%roughage been used.

Although reported efficiencies are similar,they do not include a heifer that died of bloaton the self-fed (no hay) treatment.Accounting for that heifer changes daily gainto 2.58 lb/day and feed/gain to 6.80. Weobserved no apparent advantage to feeding atotal mixed ration vs using self-feeders andoffering an equivalent amount of roughage inthe feed bunk.


23

Table 1. Performance, Net Energy Values, Carcass Traits, and Economics (Trial 1)Treatmenta

Ingredient WSC-0 WSC-4 WSC-8 DRC-8

In wt., lb 632 633 632 634Payweight out, lb 1149 1152 1171 1190b

Daily gain, lb 3.12 3.13 3.24 3.35Daily feed, lb DM 18.6 19.6 20.5 21.6c

Feed/gain 6.06 6.33 6.37 6.54d

Corn/gain 5.41 5.41 5.21 5.32NEm, Mcal/cwt

Diet 98.3 94.7 93.5 91.8d

Corn 102.7 100.1 100.7 98.7NEg, Mcal/cwt

Diet 67.6 64.4 63.3 61.9d

Corn 70.4 68.5 69.0 67.3Hot carcass wt, lb 704 703 731 753d

Dressing pct. 61.3 60.9 62.6 63.3Backfat, in .36 .39 .50 .51c

KPH fat, % 2.37 2.34 2.52 2.55e

Marbling Mt Mt Mt Mtd,f 12 28 71 60

Choice, % 100 100 100 100Liver data

Abscessed, % 35 13 9 7g

Severity score .48 .17 .17 .44h

Cost of gain, $/lb .449 .464 .460 .469i

BE at 1150, $/cwt 72.47 73.10 73.35 73.77j

Profit (loss), $/headk

Sold live 28.27 21.83 28.96 30.39In the meat 4.28 (5.60) 20.60 33.96

WSC=whole shelled corn; DRC=dry rolled cor n ; 0, 4, or 8 is percentage alfalfa hay in the dieta

(dry basis). Final live weight pencil shrunk 4% . Linear (P<.03). Linear (P<.10).b c d

Percentage kidney, pelvic, and heart fat . Mt=modest. Treatment effect (P=.11) using Chi-e f g

square. 0=no abscess, 3=severely abscessed. Based on $2.40/bu corn. Ration costs markedh i

up 20%, and $.35/head/day charged for yardage and interest . Breakeven price for 633 lbj

feeders at $95/cwt . Based on live weight price of $75/cwt and carcass price of $119/cwt.k

Table 2. Performance of Heifers Fed Whole Shelled Corn in a Total Mixed Ration orSelf-Feeders (Trial 2)

Treatmenta Item TMR Self Self + Hay SEM

Beginning wt, lb 711 722 712End wt, lb 1006 1003 1012Daily gain, lb 3.29 3.12 3.33 .097b

Daily feed, lb dry matter 18.8 17.5 18.6 .38c

Feed/gain 5.71 5.59 5.59 .121

TMR=total mixed ration; Self=self-fed whole corn plus pelleted supplement self-fed; Self +a

hay=self-fed plus 4% hay provided in feed bunk . Roughage vs none (P=.19) . Roughageb c

vs none (P=.06).


24


ROUGHAGE LEVEL AND CORN PROCESSING INFINISHING DIETS: SUBACUTE ACIDOSIS

S. A. Shuey, R. T. Brandt, Jr.,S. M. Gramlich, and C. T. Milton

Summary

Roughage level and method of cornprocessing were evaluated for the propensityto cause subacute acidosis in a controlledacidosis challenge model. Four ruminallyfistulated steers were adapted to a high graindiet, randomly allocated within a 4 × 4 Latinsquare, and fed a corn-based finishing rationat 2% of BW/day (dry basis) in two equalfeedings. Chopped alfalfa hay was used asthe roughage source and added at 8% of thediet dry matter or not added. Corn was fedeither whole (WSC) or dry rolled (DRC).Roughage level and grain processing had noeffect on postchallenge molar percentage ofacetate or total volatile fatty acid production.An interaction (P<.05) was seen in both per-cent propionate and acetate:propionate ratio.Eliminating roughage in the WSC dietresulted in increased production ofpropionate and a lower acetate:propionateratio. Ruminal pH at 3 hours postchallengeand intake during the recovery period werelower (P<.05) for 0 vs 8% roughage.Ruminal pH at 3 and 6 hours postchallengewas lower (P<.05) for DRC than for WSC.Intake during the recovery period did notdiffer between DRC and WSC. Hours belowpH 5.6 were greater (P<.05) for DRC vsWSC and for 0 vs 8% roughage. Thoughstatistically higher (P<.05), no biologicallysignificant levels of lactate were found foreither DRC or WSC. This study indicatesthat adding roughage or feeding WSC vsDRC reduces the propensity for subacuteacidosis.

(Key Words: Cattle, Grain Processing,Roughage Level, Rumen pH, Acidosis.)

Introduction

Research has shown that decreasingroughage in finishing diets leads to improvedfeed efficiency and decreased cost of gain.This is most likely due to higher digestibleenergy values for grain than roughage.However, low or no roughage may result inincreased incidences of liver abscesses anddigestive upsets. Acute rumen acidosiswould be the digestive upset most commonlyexpected. However, subacute acidosis mayrepresent a larger problem, becausereductions in feed efficiency and weight gain,caused by fluctuations in dry matter intake,exist even though cattle may not be clinicallyill. Our study was conducted to determinethe propensity for subacute acidosis with twodifferent roughage levels. We also comparedwhole shelled vs dry rolled corn becausewhole shelled corn is thought to have someroughage value and, thus, may be usedsuccessfully in a diet with a lower level ofroughage.


Four ruminally fistulated black-baldysteers (550 kg) were adapted to a high graindiet, randomly allotted within a 4 × 4 Latinsquare with a 2 × 2 treatment structure, andfed a corn-based finishing diet at 2% ofBW/day (dry basis). Chopped a lfalfa hay wasthe roughage source and was added at 8% ofthe diet dry matter or not added. Corn waseither whole shelled (WSC) or dry rolled(DRC). All diets were isonitrogenous(11.8% crude protein). Each 15-day periodconsisted of a 10-day treatment adaptation(diet dry matter at 1% of BW at 8 a.m. and 8p.m.), a fasting period (no feed given at 8


25

p.m. on day 11), a feeding challenge on day12 (1.5% of BW in a bunk at 8 a.m. plus 1%of BW via rumen fistula 1.5 hours later), andan intake recovery period when feeding re-turned to the prechallenge regimen. On thechallenge day, any uneaten feed at 1.5 hourspostfeeding was given via the rumen fistula.Feed refusals were weighed and discardedeach day prior to the 8 a.m. feeding . At thebeginning of each period, steers were inocu-lated with 1 liter of ruminal fluid from acommon donor. Ruminal samples wereobtained at feeding and 3, 6, 9, 12 hourspostfeeding (day 10); 3, 6, 9, 12, 18, 24hours postfeeding (day 12); and 12 and 24hours after the a.m. feeding on days 13-15.Ruminal samples were analyzed for pH andconcentrations of volatile fatty acids (VFA)and lactate (L).


Date are shown in Table 1. Neitherroughage level nor grain processing had aneffect on postchallenge molar percentageacetate (49%) or total VFA (10 6 mM). Aninteraction was seen for both propionateconcentration and acetate:propionate level.Eliminating roughage in the WSC dietresulted in an increased percentage ofpropionate and a correspondingly lower

acetate:propionate ratio. Roughage levelhad no effect on those measures in the DRCdiet. Though statistically different (P<.05),no biologically significant levels of lactatewere observed. Intake during the recoveryperiod did not differ between DRC and WSC.Ruminal pH at 3 hours postchallenge andintake during the recovery period were bothlower (P<.05) for 0 vs 8% roughage (5.29 vs5.69 and 1.7 vs 1.9 %BW/day, respectively).Ruminal pH at 3 and 6 hours post feeding onthe challenge day was lower (P< .05) for DRCthan for WSC (Figure 1), and pH remainedbelow 5.6 longer for DRC (P<.05; Table 1).Hours below pH 5.6 averaged 10.62 at 0%roughage vs 7.72 for 8% (P<.06). Theaddition of roughage to the diet most likelyincreased mastication time and, thus,increased the amount of sali va available in therumen for buffering. Increased salivaproduction probably allowed the rumenenvironment to remain mor e stable during thechallenge period and allowed a more rapidreturn to the prechallenge intake level.Lower rumen pH for DRC than WSC mayhave been due to a combination of theroughage value attributed to the WSC andthe faster fermentation (acid production)from the DRC. Therefore, this studyindicates that adding roughage or feedingWSC vs DRC reduces the propensity forsubacute acidosis.

Table 1. Ruminal Fermentation Patterns during Subacute Acidosis Challenge Dry Rolled Corn Whole Shelled Corn Item 0% Alf. 8% Alf. 0% Alf. 8% Alf.

Total VFA, mM 110.78 102.99 106.04 105.11Acetate, % 46.37 48.87 45.85 49.93Propionate 40.84 40.35 43.01 39.75a

Acetate:Propionate 1.22 1.36 1.09 1.45a

Lactate, mM .09 0.13 0.06 .05b

Hours below pH 5.6 11.28 10.35 9.95 5.08cd

Intake Recovery (%BW) 1.69 1.94 1.74 1.90d

Roughage level × grain processing interaction (P<.05).a

Dry rolled vs whole shelled corn (P<.01).b

Dry rolled vs whole shelled corn (P<.05).c

0 vs 8% roughage (P#.06). d


Figure 1. Effect of Corn Processing and Level of Roughage on Ruminal pH

26


27


EFFECTS OF ALFALFA FORM AND LEVELON SUBACUTE ACIDOSIS

B. J. Healy, R. T. Brandt, Jr., and S. M. Gramlich

Summary

Eight ruminally cannulated crossbredsteers (1225 lb) were used to investigate theeffects of 5 vs 10% alfalfa hay or pellets onrumen characteristics during subacuteacidosis. Alfalfa hay was obtained from onesource, and alternate bales were eitherchopped (3- to 4-inch length) or ground andpelleted (3/8-inch pellet). Intake during therecovery period after feed challenges tended(P=.12) to be greater for diets containing10% alfalfa. Duration of rumen pH below5.5 was less for diets with chopped vspelleted (P<.10) or 10 vs 5% (P<.05) alfalfa.Total volatile fatty acid (VFA) concentrationsduring the challenge phase and for the overallexperimental period were increased (P<.05)when steers were fed 5 vs 10% alfalfa dietsbut were similar during the baseline andrecovery periods. The higher pH and lowerVFA concentration resulting from feeding10% alfalfa diets suggest that steers fed amoderate amount of roughage can withstandgreater fluctuations in intake without devel-oping acidosis.

(Key Words: Alfalfa, Subacute Acidosis,Finishing Cattle.)

Introduction

Roughage is a necessary component ofhigh-grain diets for finishing cattle because ithelps protect against effects of intake varia-tion on rumen and digestive function.Physical form (particle length) has beenassumed to play an integral role. Roughageis generally limited to low levels in finishingdiets to maximize energy concentration, butwhen weather and(or) mech anical breakdown

threaten to alter feed intake, ration roughagelevels often are increased. Base d on feedlotperformance and carcass traits, previousresearch (1993 KSU Cattleman's Day)suggested that average quality alfalfa (15%crude protein) provided similar ruminal bulkand(or) tactile stimulation when eitherchopped or pelleted (3/8 inch pellet size).Additionally, that study found increased feedintake and a lowered incidence and severityof liver abscesses in steers fed 10 vs 5%alfalfa. Our objective in this study was todetermine the effects of alfalfa form and levelon subacute acidosis, using an approach thatattempts to model the effect of intakefluctuations on rumen function.


The chopped hay and pellets were fromthe same source used in a previous study(1993 KSU Cattleman's Day). Alternatebales of alfalfa hay from a common lot thenwere either chopped (3- to 4-inch length) orground and pelleted (3/8-inch pellet). Eightruminally cannulated crossbred steers (1225lb) were used in two concurrent 4 × 4 Latinsquares. Treatments were arranged as a 2 ×2 factorial experiment. Main effects werealfalfa form (chopped or pelleted) and level(5 or 10% of ration DM, Table 1). Steerswere fed diet dry matter at 2% of BW in twoequal feedings (8 a.m. and 8 p.m.) for a 10-day adaptation period. On day 11, steers re-ceived their 8 a.m. feed, but the p.m. feedingwas omitted. Steers were challenged on themornings of day 12 and day 13 by offeringdiet dry matter at 1.5% of BW in the feedbunk followed by diet dry matter at 1% ofBW via the ruminal cannula 1.5 h postfeed-ing. Any offered feed that was not consumed


28

also was placed into the rumen through thecannula at that time. The challenge wasfollowed by a 3-day (day 14-16) intakerecovery period when feed was offered as inthe adaptation phase. Ruminal samples weretaken postfeeding at: 0 , 3, 6, 9, and 12 h (day10); 3, 6, 9, 12, 18, and 24 h (days 12 and13); and 12 and 24 h after the a.m. feeding ondays 14 to 16.


Intake during the recovery period tended(P=.12) to be greater for 1 0% than 5% alfalfadiets (Table 2), but alfalfa form did not affectintake. Rumen pH stayed below 5.5 longerwhen pelleted alfalfa (P<.10) and 5% alfalfa(P<.05) diets were fed. Similarly, mean pHfor the entire experimental period was lower(P<.05) when

pelleted and 5% alfalfa diets were fed.Average total volatile fatty acid (VFA)concentrations (Table 2) were similar be-tween chopped and pelleted alfalfa but wereincreased (P<.05) when 5% alfalfa diets werefed. The changes in VFA from baseline torecovery are presented in Table 3. It is notsurprising that VFA concentrations would begreater for a lower roughage diet, because atan equal intake, it provides more fermentablesubstrate. However, total VFAconcentrations were similar during thebaseline and recovery periods for both 5 and10% alfalfa diets. An increase in total VFAwas evident during the challenge phase,especially the second day of the challenge.We conclude that chopped alfalfa is morebeneficial in moderating rumen pH duringvariable intake patterns than is pelletedalfalfa. Combined with earlier results, thisstudy suggests that 10% inclusion of eitherform of alfalfa enhances and stabilizes feedintake compared to 5%.

Table 1. Diet Compositionsa

Chopped Alfalfa Pelleted Alfalfa

Ingredient 5% 10% 5% 10%

Dry rolled corn 84.96 81.10 85.62 81.28

Chopped alfalfa 5.00 10.00 ---- ----

Pelleted alfalfa ---- ---- 5.00 10.00

Supplementb 7.54 6.54 6.88 6.22

Molasses 2.50 2.50 2.50 2.50

Dry matter basis.a

Supplements were formulated so that diets c ontained 12% crude protein, .7% Ca, .3% P, .7%b

K, 1550 IU Vit A, and 27 ppm monensin.

Table 2. Effect of Alfalfa Physical Form and Level on Intake and Ruminal Fermenta-tion Characteristics

Alfalfa Form Alfalfa Level

Item Chopped Pelleted 5% 10% SEMIntake, % of BWa 1.28 1.12 1.01 1.39 .16Hours pH below 5.5bcd 20.5 25.0 26.2 19.3 1.8Mean pHde 5.28 5.14 5.14 5.28 .10Total volatile fatty acid s , mMd 114.9 119.6 121.7 112.7 6.0

a b cDuring recovery (day 14 to 16) . During challenge days (day 12 and 13) . Alfalfa form effect(P<.10). Alfalfa level effect (P<.05) . Alfalfa form effect (P<.05).d e


29

Table 3. Effect of Alfalfa Physical Form and Level on Total Volatile Fatty AcidConcentration over Time

Alfalfa Form Alfalfa Level

Item, hr postfeeding Chopped Pelleted 5% 10%

Day 10, baseline -------------------- millimoles/liter ---------------------

0 93.0 96.4 96.6 92.8

3 98.3 103.4 103.7 98.0

6 99.9 90.6 97.5 93.0

9 91.4 92.7 93.7 90.5

12 92.2 94.0 96.6 89.6

Day 12, 1st challenge

3 135.8 148.7 151.3a 133.2b

6 136.0 137.1 145.7a 127.4b

9 118.4 122.4 128.3c 112.5d

12 118.8 123.4 125.5 116.7

18 108.1 119.7 116.3 111.5

24 95.9 106.3 108.2c 94.0d

Day 13, 2nd challenge

3 179.0 180.0 186.6c 172.3d

6 178.9 177.9 199.4a 157.4b

9 141.1 149.4 157.5a 133.1b

12 132.9 143.8 147.1a 130.0b

18 126.2 128.5 133.5 121.2

24 123.2 126.2 128.1 121.3

Recovery, hr after a.m. day 14

12 95.9 106.6 102.2 100.3

24 97.0 104.4 101.8 99.6

36 95.9 104.2 99.3 100.8

48 98.1 97.6 95.9 99.8

60 92.0 98.6 89.9 100.7

72 94.3 99.0 95.3 98.0

Means in a row with unlike superscripts differ (P<.05).a,b

Means in a row with unlike superscripts differ (P<.10).c,d


30


THE EFFECT OF SODIUM BICARBONATE LEVELON RUMEN METABOLISM IN STEERS WITH

INDUCED SUBACUTE ACIDOSIS

S. A. Shuey, R. T. Brandt, Jr., and S. M. Gramlich

Summary

Sodium bicarbonate at 1 or 2% of drymatter intake was evaluated as a means ofalleviating subacute acidosis, using sixfistulated Holstein steers in a controlledacidosis challenge model. Steers were feedchallenged by withhold ing an evening feedingand then feeding 2.5% of BW for twoconsecutive mornings. Postchallenge rumenpH for control steers (no sodiu m bicarbonate)was lower (P<.05) than for steers fed either1% or 2% sodium bicarbonate, which weresimilar to each other. Hours below pH 5.6were less (P<.01) postcha llenge for steers fedsodium bicarbonate and w ere similar betweenthe 1 and 2% levels. Although sodiumbicarbonate reduced ruminal pH hours below5.6, it did not appear to alter concentrationsof volatile fatty acids or lactate in acidoticsteers. Sodium bicarbonate appears to bebeneficial in managing subacute acidosis insituations where wide intake fluctuations arecommon or expected.

(Key Words: Cattle, Sodium Bicarbonate,Rumen pH, Acidosis.)

Introduction

Conditions that cause fluctuations inintake, such as changes in weather or me-chanical breakdown, can produce subacuteacidosis, reduce finishing cattle performance,and increase cost of gain, even though thecattle are not visibly ill. Sodium bicarbonate(Bicarb) is sometimes included in finishingrations, because of its acid neutralizingcharacteristics, to prevent acidosis. In acontrolled situation, we interrupted normalfeed intake patterns and followed this by

rapid compensatory consumption to evaluatethe potential of sodium bicarbonate toalleviate induced sub-acute acidosis.


Six ruminally fistulated Holstein steers(1050 lbs) were adapted to a high grain diet;randomly allotted within a replicated 3 × 3Latin square; and fed a corn-based finishingdiet at 2% of BW/day, unsupplemented orsupplemented with 1 or 2% of Bicarb (drybasis). The basal diet contained 80% rolledcorn, 10% chopped alfalfa hay, 8%supplement, and 2% molasses. Allottedamounts of Bicarb were mixed with the basalration at feeding time. The basa l diet in thisstudy contained 12% crude pr otein, .59% Ca,and .30% P. Each 16-day period consisted ofa 10-day treatment adaptation (1% of BWfed at 8 a.m. and 8 p.m.); a fasting period (nofeed at the 8 p.m. feeding on day 11);consecutive feeding challenges on days 12and 13 (1.5% of BW in a bunk plus 1% ofBW via rumen fistula 1.5 hours after bunkoffering; 8 a.m. feeding); and an intakerecovery period in which the f eeding schedulereturned to the prechallenge regimen. Anyfeed uneaten at 1.5 hours postfeeding on thechallenge days was given via the rumenfistula. Feed refusals were weighed anddiscarded each day prior to the 8 a.m.feeding. At the beginning of each period,steers were inoculated with 1 liter of ruminalfluid from a common donor. Ruminalsamples were obtained (postfeeding) at 0, 3,6, 9, 12 hours (day 10); 3, 6, 9, 12, 18, 24hours (days 12 and 13); and 12 and 24 hoursafter the a.m. feeding on days 14-16.Ruminal samples were analyzed for pH and


concentrations of volatile fatty acids (VFA)and lactate.


Molar percentages of acetate and propi-onate, acetate:propionate ratio, total VFA,and lactic acid concentration were unaffected(P<.05) by level of Bicarb in the diet (Table1). Ruminal pH for control steers was less(P<.05) than for steers fed either the 1 or 2%levels, which were similar. Hours below pH5.6 were lower (P<.01) during the challengeperiod for steers fed Bicarb and were similarbetween the 1

and 2% levels. No treatment differences inintake occurred during the recovery period.Results of this study indicate that the additionof Bicarb altered the ruminal environment,resulting in a more favorable ruminal pHwithout changing the amounts or ratios ofmajor fermentation end-products. Total VFAconcentrations and ruminal pH reductions inthis study were lower than observed for beefbreeds using a similar model and basal diet.Higher ruminal capacity per unit of BW forHolsteins (previously documented) may bepartially responsible .Nonetheless, sodiumbicarbonate should be beneficial in situationswhere wide intake fluctuations are expectedor common.

Table 1. Effect of Sodium Bicarbonate Level on Rumen Metabolism i nSteers Inducedwith Subacute Acidosis

Sodium Bicarbonate,% of dry matter

Item Control 1%

pH 5.72a 6.06b

Total volatile fatty acids ,m M 87.07 79.60Acetate, % 52.97 55.22Propionate, % 28.95 26.25Acetate:propionate ratio 2.04 2.23Lactate, m M 0.09 0.08Hours below pH 5.6 6.54c 1.47d

abMeans without a common superscript differ (P<.05)cdMeans without a common superscript differ (P<.01)

2%

5.98b

86.7255.3627.982.160.071.82d

Figure 1. Effect of Sodium Bicarbonate Level on Ruminal pH

3 1


College of Veterinary Medicine. Provision of IBR virus by Harish Minocha, Dept. of1

Pathology and Microbiology, is gratefully acknowledged.

32


SUPPLEMENTAL CHROMIUM AND REVACCINATIONEFFECTS ON PERFORMANCE AND HEALTH OF

NEWLY WEANED CALVES

S. A. Lindell, R. T. Brandt, Jr., J. E. Minton,F. Blecha , G. L. Stokk a and C. T. Milton1 1,

Summary

Two trials were conducted to evaluatethe effects of chromium (Cr) supplementation(4 mg/hd/day in a yeast form) or nosupplementation, with or without revac-cination with a modified live viral vaccine at9 days postweaning on performance, health,and ability to withstand an IBR challengeinfection. In Trial 1, Cr supplementation hadno effect on performance of newly weanedcalves in a 28-day receiving study, butreduced the incidence of respiratory diseaseby 37%. Revaccination depressed dry matterintake and had no effect on animal health. Intrial 2, blood plasma levels of cortisol andACTH (stress hormones ) were measured at 6and 26 days postweaning. Cortisol levelswere unaffected by treatment or by time afterweaning. Plasma ACTH conc entrations werelower at 26 vs 6 days postweaning, and werereduced at 26 days by revaccination. Despitesome slight differences in rectal temperature,treatment did not appear to af fect the animals'ability to withstand a live IBR challenge. Weconcluded that supplemental Cr wasbeneficial in reducing the incidence of bovinerespiratory disease, although mediation ofstress hormones was not involved.Revaccination of newly weaned calves with amodified live viral vaccine showed noperformance or health benefit.

(Key Words: Chromium, Weaned Calves,Respiratory Disease.)

Introduction

Minimizing losses from bovine res piratorydisease continues to pose a major challengeto the beef cattle industry. Benefits fromsupplementing a variety of nutrients thatstimulate the immune response in cattle andthat may become deficient in an acute stress-disease complex have been documented.Most recently, Canadian research has shownthat chromium (Cr) supplementation canreduce the incidence of morbidity andimprove performance of stressed beef cattle.Whether Cr supplementation can have thesame effects in newly weaned calves has notbeen tested. Vaccinat ion programs for newlyreceived calves also deserve researchattention. Therefore, we studied the effectsof supplemental Cr and revaccination onperformance, health, and blood parameters ofnewly weaned calves.


Trial 1. Two hundred and four Britishcrossbred steer and heifer calves (492 lb)were separated from their dams at the KSURange Unit and delivered to the Beef Re-search Unit. Calves were individuallyweighed and held on concrete without accessto feed or water for 24 hours to imposeadditional stress. Calves then were weighedagain; treated for parasites; and vaccinatedagainst IBR, PI , BVD, BRSV (Bovishield-3

4®); and seven clostridial organisms(Ultrabac-7®). Calves were blocked byweight and allotted to one of 12 pens in a2×2 factorially arranged experiment. An


33

equal ratio of steers:hei fers was maintained ineach pen. Main effect factors were Crsupplementation (0 or 4 mg/head/day) andvaccination schedule (– or + revaccinationwith Bovishield-4® on day 9). Chromiumwas supplied in a dried yeast form that was960 ppm Cr (Alltech, Inc., Nicholasville,KY). Diets were formulated to contain 14%crude protein and were composed of (drybasis): 44.45% corn, 36.0% chopped prairiehay, 3.75% molasses, and 15 .8% supplement.Performance and health parameters weremeasured over a 28-day period.

Trial 2. This trial was conducted tomeasure plasma cortisol and ACTH levelsduring the weaning period. Twenty steermates (393 lb) to the calves used in Trial 1were individually housed and fed in an open-front barn. Processing procedures,treatments, and starting date were identical tothose for Trial 1 and resulted in five steersper treatment combination. Steers werehalter-trained, and blood samples werecollected on days 6 and 2 6 (trial termination).On collection days, steers were fitted withindwelling jugular catheters, and bloodsamples were collected every 30 minutes for4 hours (nine samples) beginning 5 hoursafter catheter placement. Samples wereanalyzed subsequently for cortisol andACTH.

Following the 26-day trial, all steers werechallenged with 300 million plaque-formingunits (PFU) of IBR virus (200 million PFUintranasally, 100 million via the conjunctiva)to assess previous treatment effects on theability of animals to withstand an infectiouschallenge. Rectal temperatures and clinicalsigns of illness were recorded over a 7-dayperiod.


Trial 1. Feed and water deprivation for24 hours resulted in a 5.6% weight loss(shrink) which took at least 9 days to re-cover (Table 1). No interactions occurredbetween Cr level and vaccination schedule;therefore, data are pooled by main effects. In contrast to other research, Cr supple-

mentation had no effect on calfperformance. However, 4 mg/head daily ofCr reduced (P=.04; Chi-square) thepercentage of calves treated for respiratorydisease by 37%. The fact that performancewas not affected in the presence of largedifferences in morbidity may be related to agood response rate to antibiotic treatmentand low number of retreatments (n=2 and 1for 0 and 4 mg Cr treatments, respectively).

Revaccination depressed dry matterintake for the receiving period b y more than.5 lb per day (P<.05). Revaccination had noeffect on daily gain, feed efficiency, orreduction in incidence of respiratory disease.

Trial 2. Neither Cr supplementation norrevaccination had an effec t on plasma cortisollevels (Table 2). Further, no differencesoccurred in cortisol concentrations betweenday 6 and day 26 of the study. Weanticipated that cortisol concentration at day6 would be elevated, becaus e calves were stillundergoing the stress of we aning at that time.Plasma ACTH concentrations were higher(P<.10) on day 6 than day 26, indicating ahigher stress level at the earlier date.Revaccination reduced (P<.02) serum ACTHlevels at day 26, with no change in plasmacortisol. The importance of this finding isunclear, because revaccination had nobeneficial effect on performance or health ofcalves in Trial 1.

Rectal temperatures of calves during theIBR challenge period are shown in Figure 1.Two calves each in the (+) Cr, (–) Revac and(–) Cr, (+) Revac groups and one each in theother two groups showed no sign of infection(measured as temperature $ 103.5ºF). Peakmorbidity occurred within 2 days afterinfection and lasted approximately 3 days. ACr supplementation by revaccinationinteraction (P<.03) showed that Crsupplementation or revaccination alonereduced average rectal temperature by .5ºFduring the challenge period, compared tocontrol. However, the combination ofrevaccination and Cr supplementation had noeffect on mean rectal temperature. Althoughslight differences were noted, treatment did


34

not appear to have a physiologicallysignificant effect on the calves' ability towithstand an IBR viral challenge.

Results of these studies indicate thatsupplemental Cr can reduce morbidity ofweaned calves. However, me diation of stresshormones was not involved, suggesting thatsupplementation corrected a Cr deficiency.Fermentation products or yeast preparationssimilar to that used in th is study contain other

nutrients and growth factors that reportedlystimulate ruminal diet digestion and(or)animal performance. Lack of a performanceresponse in Trial 1 for the yeast treatmentsuggests that no response was directlyattributable to the yeast. Revaccination ofnewly weaned calves showe d no performanceor health benefit.

Table 1. Effect of Chromium Supplementation (as Yeast) and Revaccination on Performance andHealth of Newly Weaned Calves (Trial 1)

Supplemental Cr, mg/hd/d Revaccination a

Item 0 4 Probability – + Probability

No. pens 6 6 6 6

No. head 102 102 102 102

Weaning wt, lb 492 491 494 489

Processing wt, lb 463 465 466 461b

Shrink, % 5.93 5.23 5.6 5.6b

Day 9 wt, lb 490 492 495 489

Day 30 wt, lb 547 546 547 545

Daily feed, lb dry matter 13.45 13.28 NS 13.63 13.09 .05f

Daily gain, lb 1.96 1.97 NS 1.92 2.00 NSc

Feed/gain 6.90 6.76 NS 7.09 6.54 NS

Treated, % 34.3 21.6 .04 28.4 27.5 NSd

Retreated, % 5.7 4.5 NS 3.4 7.1 NSe

Death loss, % 0 0 0 0

Revaccinated (+) or not (–) on day 9 with modified live IBR, P I , BVD, and BRSV.a3

Following 24 hours of feed and water deprivation.b

From weaning weight.c

Treated for respiratory disease.d

Percentage of treated cattle treated twice or more.e

Not significant.f


Table 2. Serum Cortisol and ACTH Concentrations in Calves at 6 and 26 Days Postweaning (Trial

B)

Item0 mg/hd/d Cr

– Revac + Revac

4 mg/hd/d Cr

– Revac + Revac S E M

Cortisol, ng/ml

Day6

Day 26ACTH, pg/mla

Day6Day 26b

11.8 9.8 11.5 12.4 2.19

13.3 13.3 13.2 12.3

138.8 120.5 129.0 132.7 7.17

133.5 108.3 129.0 114.8

aDay 6 vs day 26 (P<.10).bEffect of revaccination (P<.02).

Figure 1. Rectal Temperatures of Steers Challenged With IBR Virus

3 5


College of Veterinary Medicine.1

36


EFFECTS OF SUPPLEMENTAL TRACE MINERALSAND PREVACCINATION ON STRESSED CALVES

S. A. Lindell, R. T. Brandt, Jr., G. L. Stokk a ,1

S. M. Gramlich, and C. T. Milton

Summary

Two trials were conducted to evaluatethe effect of high dietary levels of traceminerals on performance and health ofstressed calves. In trial 1, 221 Brahmancrossbred steers (674 lb, 1/8 to 1/4 Brahman)were used to evaluate the effect of copper(Cu) and zinc (Zn) supplementation onperformance and immune response. Thesteers were shipped from northern Texas tothe KSU Beef Research Un it with an 18-hourtransit time. Receiving diets were formulatedto contain 1) NRC-recommended levels ofCu and Zn or 2) 4 times re commended levels.In trial 2, 112 Angus cross steers (518 lb)were used to evaluate effects of the sametrace mineral supplementation andpreweaning vaccination on performance andimmune response. Half of the steers werevaccinated (modified live IBR, BVD, P I ,3

BRSV) 14 days prior to weaning, and allwere vaccinated at weaning (day 0). Nodifferences occurred in dry matter intake,daily gain, serum Zn and Cu , or IBR antibodytiter as a result of trace mineral level in eitherstudy. Prevaccination had no effect onperformance or health of weaned calves.However, IBR antibody titers at weaning(day 0) were higher (P<.001) forprevaccinated vs non-prevaccinated calves.We concluded that either the level of stressimposed in the two trials was not greatenough to cause acute trace mineral defi-ciencies, or that NRC-recommended levelsare adequate for stressed as well as non-stressed animals. Prevaccination with amodified live vaccine resulted in an elevated

antibody titer response but no improvementin health of newly weaned calves.

(Key Words: Bovine Respiratory Disease,IBR, Zinc, Copper, Morbidity.)

Introduction

Approximately 80% of all deaths ofnewly received calves in commercial feedlotsis due to bovine respiratory disease (BRD).Stress and infection generally result in lowerfeed intake and increased mineral excretion,thus depleting mineral reserves that areessential to the immune system. Otherresearch has shown that elevating levels ofsome nutrients (e.g., Zn a nd Cu) in feeds mayincrease performance and reduce morbidity.A functional immune system is critical beforestressors are incurred. One strategy toenhance immune response is to vaccinateagainst pathogens involved in BRD beforeweaning, followed by a booster at weaning.These studies were initiated to determine iffeeding high levels of Zn and Cu, as well asvaccinating against respiratory disease beforeweaning, would enhance performance andhealth of stressed calves.


In trial 1, 221 head of Brahman crosssteers (674 lb) were used to evaluate theeffects of high levels of trace mineralsupplementation on performance and healthin a 30-day study. The steers were shippedfrom northern Texas with a n 18 hour transittime and were randomly allotted to four pens


37

(two pens/treatment). The control (1X) dietwas formulated to meet NRC-suggestedlevels for Cu (10 ppm) and Zn (40 ppm).The treatment diet (4X) was formulated withfour times those amounts. Diets consisted ofcorn, silage, molasses, and alfalfa hay (Table1). Blood samples were taken upon arrivalfrom Texas and upon completion of the trialand were analyzed for Zn and Cu.

In trial 2, 116 Angus crossbred steers(518 lb) from the KSU Cow-Calf Unit wereused to evaluate the effects of high-level tracemineral supplementation and preweaningvaccination in a 35-day receiving study. Halfof the steers were given Bovishield-4® 14days prior to weaning. On October 1, 1992,steers were weaned (day 0) and shipped tothe KSU Beef Research Unit. Upon arrival,steers were held on concrete without accessto feed and water for 24 hours to inducefurther stress. The followin g day, steers wereweighed, eartagged, treated for parasites(Ivomec®), vaccinated (Bovishield-4®,Ultrabac-7®), and assigned to one of 16 pensin a 2 × 2 factorially arranged, completelyrandomized design (four pens per treatment).Diets were the same as for trial 1. Bloodsamples were obtained on days 0 and 35 andwere analyzed for Zn and Cu and IBRantibody titer.


In trial 1, steers consuming 4X diets weresimilar to those consuming the 1X in dailygain, feed efficiency, serum Cu and Zn, andmorbidity (Table 2). Similar

results were obtained in trial 2 (Table 3). Inaddition, in trial 2, IBR titers were similarbetween trace mineral levels. No differenceswere observed for steers that were vaccinatedpreweaning vs controls in dry matter intake,daily gains, feed efficiency, or serum Zn andCu. IBR antibody titer was significantlyelevated at day 0 (P<.001) in prevaccinatedcalves. However, no differences occurred inIBR antibody titers at day 35.

Feeding high levels of Zn and Cu did notincrease serum levels, most likely because ofhomeostatic mechanisms of the body. SerumZn and Cu levels at day 0 indicated thatcalves were not deficient (>1 ppm), so aresponse to supplementation would not beexpected. Unfortunately, it is difficult topredict whether stressed feeder cattle aredeficient in important trace nutrients onarrival. Therefore, fortifying receiving dietswith trace nutrients (no t necessarily at 4X therequirements) seems feasible as aprecautionary measure. In trial 1, morbidityrate from BRD was very low at 3.2% (7head). The response to treatment was verygood with few repulls. We recorded nomortality and a 100% first-time response totreatment. In trial 2, the highest morbidityoccurred during weeks 3 and 4, with themajority occurring during days 22 through28. The overall morbidity rate from BRDwas 29% (34 head), which is typical of thatexpected in newly weaned calves. Responseto treatment was also very good, with nomortality and a 90% first-time response totreatment. Both trials indicated that the viralpathogens IBR, BVD, PI3, and BRSV werenot primary factors in BRD and that bacterialagents were likely the primary pathogens.

Table 1. Composition of Total Mixed Rations for Trials 1 and 2a

Ingredient As Fed Basis % Dry Matter %Corn 43.9 47.77Silage 11.6 4.79Supplement 7.0 7.75Molasses 4.0 3.76Alfalfa hay 33.5 35.93Total 100 100

Rations contained 12.7% crude protein, .55 % Ca, .3% P; 1X and 4X diets contained 13.7 anda

54.65 ppm Cu and 47.01 and 194.45 ppm Zn, respectively. Supplemental Cu and Zn weresupplied as copper sulfate and zinc oxide, respectively.


38

Table 2. Effects of Trace Mineral Supplementation on Performance, Health andBlood Constituents of Newly Received Calves in Trial 1

Treatment a

Item 1X 4X SEM

Pen/trt. 2 2Head/trt. 110 111In wt. 669 679 10.33End wt. 772 772 8.32Daily gain, lb 3.34 3.00 .187Daily feed,

lb dry matter 22.15 21.48 .222Gain/Feed .151 .139 .0077Day 0

Serum Zn, ppm 1.12 1.05 .063Serum Cu, ppm 1.26 1.28 .042

Day 30Serum Zn, ppm .996 1.11 .048Serum Cu, ppm 1.84 1.86 .080

Morbidity, head 5 2

1X = formulated using NRC recommendations for Cu and Zn. 4X = formulated with foura

times the 1X level.

Table 3. Effect of Trace Mineral Supplementation and Prevaccination (PV) onPerformance, Blood Constituents and Health in Trial 2

Treatment a

Item 1X 4X PV(-) PV(+)SE M

No. pens 8 8 8 8Head/trt. 58 54 58 54In wt. 519 516 515 519 4.7End wt. 584 582 581 585 5.6Daily gain, lb 1.88 1.89 1.89 1.87 .080Daily feed,

lb dry matter 11.6 11.6 11.6 11.8 .28Gain/feed.161 .161 .163 .160 .0046Day 0

Serum Zn ppm 1.40 1.36 1.36 1.39 .0428Serum Cu, ppm 1.58 1.63 1.57 1.64 .0526IBR titer 1:1 1:1 1:1 1:2 .576b

Day 35Serum Zn, ppm 1.40 1.39 1.48 1.33 .0445Serum Cu, ppm 1.54 1.55 1.53 1.56 .0335IBR titer 1:4 1:4 1:4 1:4 .984

Morbidity 17 17 18 16

1X = formulated using NRC recommendations for Cu and Zn. 4X = formulated with foura

times the 1X level. PV = preweaning vaccination with Bovishield - 4®.Prevaccination vs non-prevaccination (P<.001)b


39


EFFECT OF MORNING VS EVENING FEEDING OFLIMIT-FED HOLSTEINS DURING SUMMER MONTHS

C. D. Reinhardt and R. T. Brandt, Jr.

Summary

Thirty-eight Holstein steers (avg 339 lb)were grouped into four weight blocks, withtwo pens per block. Within each block, cattlein one pen were fed at 8:00 a.m. and those inthe other at 8:00 p.m. All cattle were limit-fed to achieve a programmed rat e of gain of2.2 lbs/d using NRC net energy equations.The trial lasted from July 13 through Sep-tember 6, 1993. With the same quantity offeed, cattle fed in the evening gained 18%faster than cattle fed in the morning (P<.02)resulting in better feed efficiency for theevening-fed cattle (P<.06). Average hightemperature for the 56-day period was 8 8EF,average low temperature was 6 9EF, averagerelative humidity was 73%, and average windspeed was 1.8 mph. Feed tended to beconsumed within a 3-hour period, regardlessof time of feeding. Because the effectiveambient temperature frequently rose abovethe upper critical temperature for cattle(77EF), animals needed to expen d energy todissipate excess heat. These results indicatethat cattle limit-fed during the summer mayutilize metabolizable energy more efficientlyif allowed to ferment the bulk of their feedduring the cooler hours of the evening.

(Key Words: Limit-Feeding, Heat Stress,Night Feeding.)

Introduction

A large amount of heat is generatedduring fermentation of feedstuffs in therumen. When ambient temperatures exceedthe upper critical temperature of thethermoneutral zone, cattle must expendenergy to dissipate excess heat to maintain

their body temperature. If limit-fed cattle areprogrammed for a particular gain using NRCnet energy values, and heat dissipationreduces efficiency of metabolizable energyuse for gain, cattle will not achieve thedesired rate of gain and will be less efficient.Therefore, we compared efficiencies of cattlelimit-fed in the morning vs the evening.


Thirty-eight Holstein steers were steppedup to a medium-energy ration containing54% rolled corn, 25% sorghum silage, 11%soybean meal, 7% supplement, and 3%molasses (dry matter basis) and weighed onJuly 13, 1993 (avg 339 lb). Cattle weregrouped into four weight blocks and equallystratified within blocks into two outdoor,unshaded, concrete-floored pens. One penper weight block was assigned to morningfeeding and one pen to evening feeding.Morning-fed cattle were f ed at 8:00 a.m., andevening-fed cattle were fed at 8:00 p.m. Incalculating daily feed requirements, weassumed that the maintenance requirement ofHolstein steers was 13% greater than that ofbeef breeds (87 vs. 77 kcal/B W ). Energy.75

required for gain was ass umed to be the sameas for large frame beef calves. Diet netenergy values were taken from NRC tabularvalues. Intakes were adjusted every 14 daysbased on the assumed rat e of gain. At the endof the experiment, all cattle were fed in themorning for two consecutive days andweighed on the third consecutive day(September 6, 1993, avg 438 lb). Weatherdata were provided by the Kansas StateUniversity Weather Data Library inManhattan.


40

Table 1. Performance of Limit-Fed Cattleduring the Summer when Fed inthe Morning or Evening

Item Morning Evening SEM

Number of pens 4 4Number of head 19 19DM intake, lbs/d 9.3 9.4 .286DM intake, % of BW 2.3 2.3 .081Daily gain , lb 1.66 1.96 .043a

Feed:Gain 7.46 6.37 .303b,c

Means differ (P<.02).a

Means differ (P<.06).b

Analyzed as Gain:Feed.c


By design, daily dry matte r intakes wereequal across all pens when expressed as apercent of body weight (Table 1). However,neither treatment group realized the desiredrate of gain of 2.2 lbs/day. Cattle fed in theevening gained faster (P<.02) and,subsequently, more efficiently than those fedin the morning (P<.06). Average hightemperature for the 56-day period was 8 8EF,average low temperature was 6 9EF, averagehumidity was 73%, and average wind speedwas 1.8 mph.

The thermoneutral zone (the range ineffective ambient temperature for which nophysiological adaptation must be made tomaintain homeostasis) for beef cattle is from59 to 77EF. Effective ambient temperatureincreases with rising relative humidity,because cattle are less able to cool themselvesthrough sweating and respiratoryevaporation. Sunny conditions elevate theeffective ambient temperature 5 to 9EF bydirect and indirect radiant heat.

Ruminal fermentation of high-grain dietspeaks during the first 12 hours after con-sumption. Hence, cattle fed in the eveningdigest the bulk of their daily allotment of feedbetween sundown and su nrise, whereas cattlefed in the morning experience a fermentationpeak during the hottest part of the day. Ifcattle are already experiencing heat stress, theheat of fermentation adds to the animals' totalheat load and increases the energyexpenditure needed for heat dissipation.Slightly increased respiration from heat stresscan increase the maintenance energyexpenditure by 7%, and heavy, laboredpanting can increase the maintenance energycost by 11 to 25%. Our data suggest that,during the summer, cattle limit-fed in theevening convert feed to gain more efficientlythan those fed in the morning.


Appreciation is expressed to Jon Ferguson, Kensington, for supplying cattle, to Dr. Vincent1

Traffas, Smith Center, for technical assistance; and to Pitman-Moore for financial support.

41


IMPLANTING SUCKLING HEIFER CALVES:GROWTH AND SUBSEQUENT PERFORMANCE 1

D. D. Simms

Summary

A total of 361, suckling, he ifer calves wasused over a 2-year period to ass ess the effectsof implanting with either Ralgro® orSynovex-C® on growth and subsequentperformance as replacement females. Bothimplants increased (P<.01) weaning weightsover that of controls, with the weightincrease being retained by yearlings. Pelvicarea also was increased at 1 year of age byboth implants, with Synovex-C producinglarger (P<.01) pelvic areas than Ralgro.However, just prior to calving, body weightand pelvic area were similar among treat-ments. Uterine scores, cycling activity priorto breeding, percentage exhibiting estrus, andpregnancy percentage were similar for alltreatments. Implanting tended to reducefirst-service conception rates. Synovex-C-implanted heifers calved later (P<.05) thanRalgro-implanted heifers and, consequently,their calves tended to be lighter at weaning.Levels of calving difficulty we re similar for alltreatments. In summary, implanting sucklingheifer calves at 2-4 months of age willincrease growth rate, but this researchindicates some potential for reduction inreproductive performance.

(Key Words: Beef Heifers, Implants,Ralgro®, Synovex-C®, Calving Difficulty.)

Introduction

Implanting suckling heifer calves signif-icantly increases weaning weight. However,because some heifers will be retained asreplacements, the effect of implanting onsubsequent reproduction a nd/or production iscause for concern. Consequently, this re-search was conducted to compare the effectsof Ralgro and Synovex-C on the growth rateof suckling heifer calves and their subsequentperformance as replacement females.


Over a 2-year period, a total of 361,suckling, heifer calves were allotted by orderof birth and pasture to the followingtreatments: 1) controls - nonimplanted, 2)Ralgro - a single 36-mg implant, or 3)Synovex-C - a single implant containing 100mg Progesterone + 10 mg Estradiol.

The heifers were individually weighed atimplantation (3 month old, n=120/trt), atweaning (n=120/trt), at approxi mately 1 year-of-age (n=95/trt), and at approximately 1month prior to the start of calving (n=68/trt).As heifers were culled from the herd, everyeffort was made to retain equal numbers ineach treatment group. From weaningthrough calving, the heifers were managed asone group.

Pelvic area was measured as yearl ings andat precalving, and uterine scores were takenat the same time as the yearling weight.


42

Blood samples, collected 10 days apart priorto initiating a synchronization program, wereanalyzed for progesterone to establish cyclingactivity. Thirty-two days prior to the start ofbreeding, 0.5 mg melengestrol acetate(MGA) per day was fed for 14 days.Seventeen days after removal o f MGA fromthe ration, the heifers were injected withprostaglandin. Those visually detected inheat following synchronization wereartificially inseminated with semen from low-birth-weight EPD Angus bulls. Afterapproximately 5 days of breeding, low-birth-weight EPD Angus bulls were placed withthe heifers for an additional 40 days.


Results are summarized in Table 1. Both implants increased (P<.01) weaningweight over that of controls, and this in-crease was still present at 1 year of age. However, shortly before the start of calv-ing, body weights were all similar.

Both implants increased (P<.01) pelvicarea over that of controls at 1 year of age,and Synovex-C-implanted heifers had largerpelvic areas than Ralgro-implanted heifers.However, shortly before calving, all threetreatment groups had similar pelvic areas.

Prior to breeding, no difference occurredamong treatments in uterine scores o r in thepercentage of heifers with bloodprogesterone levels high enough (> 1 µg/ml)to indicate cycling activity.

Implanting tended to reduce first-serviceconception rates, but pregnancy rates at theend of the 45-day breeding season weresimilar among treatments.

As might be expected from the pelvicareas, calving difficulty scores were allsimilar. However, that may be misleading,because calving difficulty was low in alltreatments.

The average calving date was earlier(P<.05) for the Ralgro-implanted heifers thanfor the Synovex-C-implanted h eifers, with thecontrol heifers intermediate . The older calvesproduced by the Ralgro-implanted heiferswere slightly heavier at weaning than thosefrom the Synovex-C-implanted heifers, butthe difference wasn't significant. The ADGof the calves from birth to weaning was thesame for all treatments, which we interpretedas indicating similar levels of milk production.

Apparently, producers can implantsuckling heifer calves at branding with eitherRalgro or Synovex-C and obtain increasedweaning weights; however, this researchindicates a slight negative impact onreproduction. For example, implantingtended to reduce first-service conceptionrates, which could be significant in an AIprogram, especially when using expensivesemen. Additionally, later calving dates forSynovex-C-implanted heifers compared tothose implanted with Ralgro translate intolighter calf weaning weights. Also, thisresearch shows that the claims thatimplanting suckling heifers will reducesubsequent calving difficulty are not justified.


43

Table 1. Effects of Implanting Suckling Heifers with Ralgro or Synovex-C onGrowth and Subsequent Reproductive Performance

Treatment

Item Controls Ralgro Synovex-C

Growth

Weaning wt, lb 441f 452g 455g

Yearling wt, lb 689f 701g 712g

Precalving wt, lb 993 993 1002

Pelvic area

Yearling, cm2 142f 152g 156h

Precalving, cm2 230 233 234

Reproduction

Uterine scoresa 4.5 4.5 4.5

Cycling, % b 72 67 63

Exhibited estrus, %c 95 77 92

1st service conception, % 78 66 55

Pregnant, %d 87 85 89

Average calving date 3/9ij 3/6i 3/12j

Calving difficulty

Average calving scorese 1.3 1.2 1.4

First calf performance

Birth wt, lb 73.4 72.1 74.2

Weaning wt, lb 394 401 391

ADG, lb 1.63 1.65 1.64

1 = infantile tract, 5 = large tract with evidence of cycling activity.a

Based on circulating progestero ne levels (>1 µg/ml) with the last blood sample taken 32 daysb

prior to the start of breeding.% exhibiting estrus following synchronization.c

% pregnant following the 45 day breeding season.d

1 = no difficulty, 5 = Caesarean section.e

Values with different superscripts are significantly different (P<.01).f,g,h

Values with different superscripts are significantly different (P<.05).i,j


44


EFFECT OF STAGE OF GROWTH AND SAMPLINGPROCEDURE ON THE TRACE MINERAL CONTENT OF

KANSAS NATIVE GRASS

J. D. Arthington, L. R. Corah, and S. D. Utter

Summary

To determine the trace mineral content ofKansas native grasses, samples werecollected from four locations of tall orintermediate grasses and four locations ofshort grasses. Copper (Cu) and zinc (Zn)levels tended to be lower during dormancythan in the growing season; however, manga-nese (Mg) and iron (Fe) levels wereessentially the same throughout the year. Interms of meeting the dietary requirements ofgrazing cattle, Cu was adequate in June butmarginal in February, whereas Zn wasmarginal to deficient at both collection times.

In addition, the impact of grazing selec-tivity on the validity of trace mineral analysisof hand-clipped pasture samples wasevaluated. Although samples collected viarumen cannulae from grazing stee rs containedhigher (P<.01) levels of protein, calcium, andphosphorus than comparable hand-clippedsamples, no differences occurred in the tracemineral contents.

(Key Words: Trace Mineral, Forage, Graz-ing Selectivity, Native Grass.)

Introduction

The evaluation of trace miner a l content offorage is important when attempting toidentify deficiencies. Because the crudeprotein, calcium, and phosphorus contents ofKansas native grasses vary greatly dependingon the stage of growth, it seemed logical thatthe trace mineral content also might varyduring the year. Another im-

portant consideration when attempting toutilize forage tests in ration balancing is theinfluence of animal selectivity. Given theopportunity, animals will selectively grazeforages of greater palatability and highernutritional value than the average forage inthe pasture. Depending on the amount offorage available, selectivity can be a majorfactor in the quality of forage consumed.This research was conducted to determineseasonal variations in trace mineral contentand to assess the accuracy of clipped samplesin predicting animal consumption of traceminerals.


Clipped, native grass samples from fourtall or intermediate grass and four short grassrange sites in central and western Kansaswere collected in both early June and lateFebruary to represent two extremes in theplant life cycle. Clipped samples were takenfrom the same pasture location on eachcollection date. Trace mineral analysis wasconducted using inductively coupled plasma(ICP) spectrometry (Peterson Laboratories;Hutchinson, KS).

To evaluate the impact of grazingselectivity on trace mineral intake, fourruminally cannulated steers were evacuatedand allowed to graze contro lled areas. At thesame time, hand-clipped samples wereobtained. The rumen of each steer was thenevacuated, and the contents were rinsed withwater until it ran clear. These collectionswere repeated four times.


45


No differences occurred in the tracemineral content of short vs tall or inter-mediate native grasses at similar stages ofgrowth (Table 1). For both grass types, Cuand Zn concentrations tended to be lowerduring dormancy than during the growingseason. Iron and Mg concentrations did notshow that trend. The level of Cu in bothforage types was adequate in June butmarginal in February in terms of meeting agrazing animal's dietary requirements. TheZn levels were marginal to deficient in bothforage types at both forage sampling times.The Fe content was adequat e in both foragetypes in June and was very high in the shortgrass samples in February.

The steers consistently selected foragehigher (P<.01) in crude protein, calcium, andphosphorus than comparable hand-clippedsamples. Increases from selectivity were30.0% for crude protein, 52.6% for calcium,and 36.8% for phosphorus. However, nodifferences occurred in the trace mineral con-tents of selected vs clipped grasses (Table 2).

This research indicates that Zn may bemarginally deficient in Kansas native rangeforages. More research is planned todetermine the importance of this potentialdeficiency. In addition, clipped pasturesamples appear to be reliab le indicators of thetrace mineral content of the grass consumedby a grazing animal.

Table 1. Trace Mineral Content of Kansas Native Grassesa

Grass TypeSampling

Time Iron Copper Zinc Manganese

Tall/intermediate June 314 ± 97 10.02 ± 1.16 19.78 ± 2.04 32.90 ± 4.18

February 352 ± 58 5.43 ± .45 14.10 ± 2.04 22.15 ± 3.19

Short June 347 ± 52 8.78 ± .84 16.30 ± 1.55 35.90 ± 2.04

February 795 ± 128 4.40 ± .39 13.04 ± 1.25 41.90 ± 2.87

Results are expressed as the mean mineral content ± SE; all results are expressed as mg/kg.a

Table 2. A Comparison of the Trace Mineral Content of Hand-Clipped vs Grazed ForageSamplesa

Collection Method Iron Copper Zinc Manganese

Steer selection 152.7 ± 16.8 10.65 ± .56 20.42 ± .54 11.32 ± .59

Hand-clipped 154.8 ± 23.7 11.49 ± .79 19.50 ± .76 12.84 ± .84

Results are expressed as the mean mineral content ± SE; all results are expressed as mg/kg.a


Extension Livestock Specialist, Chanute, KS.1


46

Table 1. Effect of Copper Sulfate and ZincOxide on Health and Gain of NewlyArrived Calves

Item Control Cu-Zn

No. calves 77 77Starting wt, lb 295 295ADG, lb

1 to 14 d 1.36 1.3915 to 28 d 1.35 1.111 to 28 d 1.36 1.2529 to 56 d 1.90 2.001 to 56 1.61 1.64

HealthMorbidity, %, 1 to 28 d 29.8 32.4Morbidity, %, 29 to 56 d 27.7 18.5Treatments/animal, 1 to 28 d 9.0 7.1Treatments/animal, 29 to 56 d 7.2 5.5


THE EFFECT OF COPPER SULFATE AND ZINCOXIDE IN A DRENCH ON THE GAIN AND HEALTH

OF NEWLY ARRIVED CALVES

F. K. Brazle and G. Stokka 1 2

Summary

One hundred and fifty-four, newlyarrived, bull calves averaging 295 lb wereeither drenched with a copper-zinc (Cu-Zn)solution or water at arrival. The Cu-Zndrench did not affect gains during a 56-daytrial. Additionally, no differences occurred inmorbidity or the number of antibiotic treat-ments required per animal.

(Key Words: Copper, Zinc, Trace Minerals.)

Introduction

Copper and zinc are important for certainenzymes in the immune system. Also, therehave been reports that highly stressed calvesmay have higher requirements than healthycalves for copper and zinc. Therefore, ourobjective was to determine if a Ci-Zn drenchat arrival would improve the health and gainof highly stressed calves.


One hundred and fifty-four bull calvesshipped from Georgia wer e allotted randomlyto receive 40 ml of either a water (control) ora Cu-Zn drench treatment. The Cu-Zntreatment contained 250 mg Cu from coppersulfate, 650 mg Zn from zinc oxide, and 400IU of Vitamin E. Additionally, they weredewormed with Inomec®, implanted withRalgro®, and mass medic ated with Micotil®.

The calves were weighed on days 1, 14, 28,and 56. The calves were vaccinated at arrivalwith modified-live IBR+BVD+P I , 7-way3blackleg, and Presponse®. On day 28, theywere surgically castrated. The calves werefed an average of 6.25 lbs per day of a 16%crude protein milled ration plus prairie hay toappetite (average consum ption of 3.7 lb/day).


The Cu-Zn drench at arrival did not affectgains through 56 days (Tab le 1), although theCu-Zn drench group tended to gain slowerduring the first 28 days. No differenceoccurred in morbidity or number oftreatments required per animal.


Appreciation is expressed to Zinpro Co-Pro, Edina, MN, for partial funding and to Richard1

Porter, Reading, KS, for supplying the cattle. Extension Livestock Specialist, Chanute, KS.2


47


THE EFFECT OF FOURPLEX® ON GAIN ANDHEALTH OF NEWLY ARRIVED CALVES 1

F. K. Brazle and G. L. Stokka 2 3

Summary

Two trials were conducted to evaluatethe effects of Fourplex®, a trace mineralsupplement, on long-hauled stocker calves.In each trial, Fourplex was added to theration of lightweight, long-hauled calves infour pens, while calves in another four pensserved as controls. Additionally, every othercalf that became sick, regardless of feed treat-ment, was drenched with a solution ofFourplex in Trial I and a Cu, Zn, Mn+Cosolution in Trial II. Fourplex in the feed didnot improve ADG, reduce morbidity, orreduce the number of treatments required persick animal. In Trial II , Fourplex-fed calvesthat became sick required more treatments(P<.12) during the first 2 weeks; however,during the third and fourth weeks, theyrequired fewer treatments (P <.03). In Trial I,sick calves drenched with Fourplex requiredmore treatments. In Trial II, drenching witha Cu, Zn, Mn+Co solution resulted in anincrease in treatments per sick calf during thefourth week. In these trials, Fourplex did notsignificantly increase performance or reducesickness.

(Key Words: Fourplex®, Copper, Zinc,Trace Minerals.)

Introduction

Copper (Cu) and zinc (Zn) have beenshown to be important for certain enzymes inthe immune system. The objective of this

study was to determine if Fourplex, a tracemineral premix containing Cu and Zn, wouldimprove the health and gain of highly stressedcalves when included in the diet or in adrench given when the calves first exhibitedsigns of sickness.


Trial I. One hundred and fifty-nine bullcalves shipped from Georgia were allottedrandomly to treatments: 1) control or 2)Fourplex fed at 15 g/head/day, whichprovides three times the NRC minimum dailyrequirement for Cu, Zn, Mn, and Co. Therewere four pens per treatment. The calveswere vaccinated at arrival with modified-liveIBR+BVD+PI , 7-way blackleg, and3Presponse®. They were individ ually weighedat processing and on day 28. Additionally,they were dewormed with levamisole,deloused with Lysoff®, implanted withRalgro®, mass medicated with Micotil®, andcastrated via banding. Every other calf pulledfor sickness from each pen, regardless oftreatment, was drenched with 100 ml ofFourplex C. This drench was made by adding21 g of Fourplex C to 100 ml of water andstraining through cheesecloth. The materialwas difficult to move through the drenchguns and had to be diluted slightly in thestraining process. A sick pen was providedfor each treatment group; therefore, thecalves remained on the original feed treat-ments while in the sick pen. Similar anti-biotic treatment strategies were used on sick


48

Table 1. The Effect of Fourplex® inthe Starter Diet for Long-Hauled Calves, Trial I

Item Fourplex Control

No. 80 79Starting wt, lb 260 252ADG, lb 1.41 1.50Morbidity, % 40.5 29.9Treatments/animal 6.9 6.5

Table 2. The Effect of Fourplex® inthe Feed on Gain and Healthof Calves, Trial II

Item Fourplex Control

No. 84 84Starting wt, lb 246 255ADG, lb 1.15 1.08Mortality, % 5.8 3.5Morbidity, % 72.0 63.4Treatments/animal

Week 1 4.6 4.1a b

Week 2 3.9 3.1a b

Week 3 5.3 4.9Week 4 4.1 6.2c d

Means in the same row with unlike super-a,b

scripts are different (P<.12).

calves regardless of feed or drench treat-ments.

Trial II . One hundred and sixty-eightcalves were allotted randomly to the samefeed treatments as in trial I with four pens pertreatment. Processing treatments andhandling procedures were also the same.However, in this trial, every other sick calffrom each pen was drenched with 10 0 ml ofa solution made with 5.4 g of Zinpro® 200,3.75 g Cuplex® 100, 3.75 g Manpro® 160,0.94 g Copro® PD, and 100 ml of water.

Rumen fluid was collected from twocalves per pen on days 1, 14, and 28. Inaddition, rumen fluid was collected from thefirst two calves that became sick from eachpen. Rumen fluid was collecte d again whenthey left the sick pen. The rumen fluid wasfrozen and later analyzed for Cu, Zn, Mn, andCo.

Results

In Trial I, no differences occurred inADG, percent morbidity, number of treat-ments per animal, or feed intake betweencontrol and Fourplex-fed calves (Table 1).Drenching sick calves with Fourplex in-creased (P<.05) the treatme nts required (10.4vs 5.3 for nondrenched calves).

In Trial II, Fourplex in the feed did notimprove ADG, reduce mortality or morbidity,or influence feed intake (Table 2). Thenumber of treatments required for sick

animals was higher (P<.12) for thosereceiving Fourplex in the diet for the first 2weeks. However, by the fourth week, theFourplex-fed calves required fewertreatments than the controls. This mightsuggest that Fourplex in the feed adds stressto the calves before the additional mineralsupplementation has a chance to improve theimmune system. However, by week 4, theimmune system may have had a chance torespond, resulting in fewer treatments peranimal. The feeding of Fourplex resulted inincreased (P<.05) rumen concentration of allminerals except Zn on days 14 and 28. Zincwas elevated in the rumen only at day 14.Feed intake was not affected by Fourplex.

Drenching tended to increase the numberof treatments required in both feed groups.In the fourth week, the difference becamesignificant (P<.08); (6.0 vs 4.2 treatments perhead). This suggests that drenching sickcalves with high doses of trace minerals onthe first day in the sick pen did not improvethe response to antibiotic therapy. More re-search data are needed to understand betterthe dosage level and effect of the drench onthe health of light-weight calves.


Appreciation is expressed to Rhone-Poulenc, Atlanta, GA, for partial funding and to1

Richard Porter, Reading, KS, for supplying the cattle. Extension Livestock Specialist, Chanute, KS.2


49


THE EFFECT OF PROTECTED LYSINE-METHIONINE ON GAIN AND HEALTH OF

NEWLY ARRIVED CALVES 1

F. K. Brazle and G. L. Stokka 2 3

Summary

Long-hauled calves averaging 293 lbwere allotted to groups fed with or withoutprotected lysine-methionine (SmartamineML®). Protected lysine-methionin e did notimprove ADG in the first 28 days but did im-prove ADG from 29 to 56 days. It alsoreduced morbidity (16.1 vs 34.2%) from day29 to 56. Based on this research, theresponse of long-hauled calves to protectedlysine-methionine in the diet appears to occurafter they have recovered from the stress ofshipment.

(Key Words: Lysine, Methionine, ProtectedAmino Acids, Stocker Calves.)

Introduction

Escape or bypass protein has been shown toimprove performance of lightweight calves,and it has been hypothesized that rumenbypass of certain amino acids might improvegain and health of calves. The objective ofthis study was to evaluate the effect ofprotected lysine-methionine (amino acids) onthe gain and health of newly arrived, light-weight calves.


One hundred and fifty-six bull and steercalves from Georgia were blocked by sexualstatus and randomly allot ted to be fed with or

without protected lysine-methionine at10g/hd/day. There were four pens pertreatment.

The calves were vaccinated at a rrival withmodified-live IBR+BVD+PI , 7-way3blackleg, and Presponse®, and weighedindividually on days 1, 14, 28, and 56.Additionally, they were dewormed anddeloused with Ivomec®, implanted withRalgro®, and mass medic ated with Micotil®.On day 28, the bull calves were surgicallycastrated.

Body temperature of all calves wasrecorded on day 14. All calves with bodytemperature over 104EF were treated withMicotil, placed in sick pens by treatmentgroup, and fed their original ration . The re-maining calves were treated with long-actingpenicillin and returned to their original pens.


The calves receiving the protected lysine-methionine gained faster (P<.10) thancontrols, with most of the increase occurringfrom days 29 to 56 (Table 1). Hay intakewas increased (P<.01) by feeding protectedlysine-methionine during the first 28 days.The calves fed protected lysine-methioninehad less sickness (P<.01) from days 29 to 56.This reduction in sickness after 29 days couldbe very beneficial, if the calves were turnedout to wheat pasture or grass.


50

In this trial, the addition of lysine-methionine to the diet showed some

potential to improve the health and gain ofhighly stressed calves; however, moreresearch must be conducted to determine ifthis response is related to improved nutritionor to an immune response.

Table 1. Effect of Protected Lysine-Methionine on Gain and Health of NewlyArrived Calves during the First 56 Days

LysineMethionine Control

No. calves 78 78Starting wt., lb 293 293

ADG, lb1 to 14 d 1.31 1.4515 to 28 d 1.36 1.101 to 28 d 1.34 1.2729 to 56 d 2.04 1.86a b

1 to 56 d 1.69 1.57a b

Feed intake, lbGrain - 1 to 28 d 5.75 5.75Hay - 1 to 28 d 4.50 4.23e f

Total - 1 to 28 d 10.25 9.98e f

Grain 29 to 56 d 6.80 6.80Hay 29 to 56 d 3.05 3.02Total 29 to 56 d 9.85 9.82

Grain 1 to 56 d 6.27 6.27Hay 1 to 56 d 3.77 3.62

HealthMorbidity, %, 1 to 28 d 27.6 32.2Treatments/animal, 1 to 28 d 8.1 8.0Body temp., d 14, EF 103.1 103.2No. dead 1 0Morbidity, %, 29 to 56 d 16.1 34.2c d

Treatment/animal, 29 to 56 d 6.1 6.6

Means in the same row with unlike superscripts are different (P<.10).a,b

Means in the same row with unlike superscripts are different (P<.01).c,d

Means in the same row with unlike superscripts are different (P<.06).e,f


Micotil is a registered trademark of Elanco Animal Health.1

Extension Livestock Specialist, Chanute, KS.2

51

Table 1. The Effect of Mass Medication ofLong-Hauled Calves with Micotil®at Arrival

Treatment Item Control Micotil®

No. calves 85 85Starting wt, lb 294 294ADG, lb 1.12 1.18Health Morbidity, % 75.6 59.7a b

Mortality, % 8.1 1.2a b

Treatments/animal Week 1 4.3 4.3 Week 2 3.9 3.1 Week 3 5.4 4.6 Week 4 4.5 5.1

Means in the same row with unlike superscriptsa,b

are significantly different (P<.05).


THE EFFECT OF MASS TREATMENT WITH MICOTIL® 1

AT ARRIVAL ON THE HEALTH AND PERFORMANCEOF LONG-HAULED CALVES

F. K. Brazle 2

Summary

Long-hauled calves (n=170 were eithermass-medicated with Micotil® or served ascontrols. Micotil reduced mortality (1.2 vs8.1%) and morbidity (59.7 vs 75.5%), but itdid not improve ADG.

(Key Words: Stocker Calves, Micotil®,Receiving Program, Shipping Fever, Health.)

Introduction

Calves hauled long distances typicallyhave high incidences of respiratory diseasesand other health complications. Micotil(tilmicosin phosphate) is a long-actingantibiotic that has shown promise in reducingrespiratory disease. Our objective was todetermine if mass medication with Micotil atarrival would reduce sickness and improvegain of highly stressed, long-hauled calves.


One hundred and seventy, mixed breed,bull calves from Alabama averaging 294 lbwere allotted randomly to either receiveMicotil (4.5 ml of IM at arrival) or serve ascontrols. All calves were vaccinated withmodified-live IBR+BVD+PI and Blackleg3(7-way), dewormed with levamisole,deloused with Lysoff®, implanted withRalgro®, and castrated via banding. Theywere fed 4.5 lbs per day of a

15.5% crude protein milled ration plus prairiehay to appetite (average, 2.9 lbs).


These calves were severely stressed asindicated by the level of morbidity and thenumber of antibiotic treatments required(Table 1). An injection of Micotil at arrivalreduced both mortality (1.2 vs 8.1%; P<.05)and morbidity (59.7 vs 75.5% ; P<.04). How-ever, it did not affect the number of antibioticinjections required to treat a sick calf and didnot improve ADG. An injec tion of Micotil tohighly stressed calves at arrival should becost effective as a result of reductions inmorbidity and mortality.


Appreciation is expressed to Dale Lanham, Woodson County Agricultural Agent and the1

Bressner Pasture Committee for their assistance. Extension Livestock Specialist, Chanute, KS.2

52

Table 1. Composition of the Commer-cial Mineral Mixture

Ingredient Percent

Calcium, not less than 7.0Calcium, not more than 8.4Phosphorus (P), not less than 7.0Salt, not less than 39.0Salt, not more than 41.0Selenium, not less than 0.0026Iodine, not less than 0.0002Potassium, not less than 1.0Magnesium, not less tha n 0.5Vitamin A, not less than 50,000 IU/lb


THE EFFECT OF FEEDING DIFFERENT LEVELS OFAUREOMYCIN® IN A MINERAL MIXTURE TO STOCKER

CATTLE GRAZING NATIVE GRASS 1

F. K. Brazle 2

Summary

Two hundred and forty-three mi xed breedsteers were allotted to four treatments withtwo pastures per treatment. Treatmentsconsisted of a free-choic e mineral supplementalone or with Aureomycin® a dded to provide150, 300, or 450 mg/hd/day. Gain wassimilar for all four treatments. The per-centage of cattle with eye problems wasreduced in pastures where 150 and 450 mg ofAureomycin were consumed daily; however,the incidence in the 300 mg/hd/day groupwas as high as in the control group.

(Key Words: Aureomycin®, Antibiotic,Mineral, Chlortetracycline, Native Grass,Stocker Cattle.)

Introduction

Aureomycin (chlortetracycline), at levelsranging from 75 to 500 mg/hd/day, has beenshown to increase daily gain of stockersgrazing native grass pastures. Additionally,it has reduced eye problems when fed at 350-500 mg/hd/day. The objective of this studywas to determine the optimum level ofAureomycin needed to control eye problemsand footrot, in addition to improving animalgains.


Two hundred and forty-three mixed breedsteers were allotted randomly to four treat-ments consisting of free-choice mineral mixesdesigned to provide 0, 150, 300, or 450mg/hd/day of Aureomycin. Each treatmentgroup was further divided into two pasturereplications for a total of eight pastures. Toattain the desired Aureomycin intake in thelast three treatments, an Aureomycin premix(50 gram/lb) was added a t 28, 56 or 84 lb perton, respectively, of a commercial mineralmixture. The composition of the commercialmineral mixture is shown in Table 1.


53

The steers grazed for 92 days. Individualweights were taken at the start and end of thetrial. Steers were commingled at weighing toremove time of weighing effects.Additionally, they were monitored each weekfor footrot and eye problems. Mineral intakewas monitored weekly.


The typical gain response to Aureomycinwas not observed in this trial (Table 2).Mineral intake was very close to the

predicted level, which resulted in Aureomycinintakes very close to the target levels. Therewas a slight but nonsignificant trend towarda reduction in footrot with the increasingAureomycin. The steers consuming 150 mgand 450 mg had a lower incidence of eyeproblems; however, the inci dence was as highin the 300 mg group as in the controls.Given the low incidence of both footrot andeye problems in the control steers, this trialmay not have been an adequate test of theefficacy of Aureomycin in preventing theseproblems.

Table 2. The Effect of Adding Aureomycin to a Mineral Mixture Supplied Free-Choice to Stocker Cattle

Treatment - mg Aureomycin/hd/day Item Control 150 300 450

No. 56 65 54 68Starting wt, lb 565 561 562 553

ADG, lb 2.57 2.58 2.57 2.58

Mineral intake, g/day 88 93 97 99

Aureomycin intake, mg/day — 143 298 458

Incidence of:Footrot, % 2.0 1.3 .4 1.0Eye problems, % 6.9 1.8 7.7 3.5b a b a

Means in the same row with unlike superscripts are different (P<.10). a,b


Southeast Kansas Branch Experiment Station, Parsons, KS.1

Southeast Area Extension Office, Chanute, KS.2

54


EFFECT OF LASALOCID AND LENGTH OF MORNINGGRAZING ON WEIGHT AND SHRINK OF STEERS

GRAZING BROMEGRASS PASTURES

K. P. Coffey , F. K. Brazl e , and J. L. Moyer 1 2 2

Summary

A total of 72 mixed breed steer s from twosources was used in an experiment todetermine the effect of las alocid and length ofmorning grazing prior to weighing on weightand shrink of steers grazing smoothbromegrass pastures. Steers were dividedinto eight groups and weighed at either 6, 7,8, or 9 a.m. on 4 separate days. Half of thesteers received a control mineral mixture andhalf received a mineral mixture containinglasalocid. Weights of purchased steers hav-ing an excitable disposition were not affected(P>.10) by length of morn ing grazing prior toweighing. However, weights of steers raisedat the Southeast Kansas Branch ExperimentStation (SEKES) increased with length ofmorning grazing. Stee rs allowed to graze for3 hours before morning weighing had thelowest (P<.05) total % shrink and total %shrink/hour by 3 p.m. Lasaloid did not affectshrink. Using these figures, cattlemen couldadd additional weight to cattle by simplyallowing them to graze longer beforegathering them for sale.

(Key Words: Shrink, Steers, Grazing Time,Marketing.)

Introduction

Cattle generally graze for 3 - to 4-h peri-ods beginning at daybreak and prior tosunset, and for 1- to 2-h periods scatteredthroughout the day. In a fall-grazing studyon smooth bromegrass at the Southeast

Kansas Branch Experiment St ation (SEKES),steers allowed to graze in the morning for 3h before weighing were 16 lb heavier thanthose weighed as the morning grazing periodbegan. This study was conducted todetermine the effect of las alocid and length ofmorning grazing prior to weighing on weightand shrink of steers grazing smoothbromegrass pastures in the summer.


Forty purchased, mixed breed steers and32 Simmental × Angus crossbred steers fromthe SEKES herd were allotted by source toone of eight, 10-acre, smooth bromegrasspastures. Within each cattle source, steersgrazing two pastures were offered a controlmineral mixture and steers grazing the tworemaining pastures were offered a mineralmixture containing lasalocid (600 mg/lb).Steers were allotted to their respectivepastures on June 3 and had grazed smoothbromegrass for at least 30 days prior tostarting the study. Steers were allowed freeaccess to water and their respective loosemineral mixture throughout the study.

All steers were removed from pasture onthe afternoons of June 24 and July 13 andweighed before and after a 16-h shrink.Steers from the control and lasalocid groupswere weighed full on June 28 and 30 and July2 and 6 at either 6, 7, 8, or 9 a.m. On eachday of weighing, each group of steers wasweighed only once, and each group of steerswas weighed at a different time on each


55

weigh day. Following their respectiveweighing on July 6, steers were placed inpens without feed or water and weighed atapproximately 2-h intervals until 3 p.m. Thiswas done to determine how lasalocid orlength of morning grazing would affect rateof shrink.


A cattle source × grazing time interactionwas detected (P<.10) for a verage full weightsmeasured between June 28, 30 and July 2, 6and weight change from the initial and finalshrunk weights (Table 1). Neit her weight norweight change from shrunk weights ofpurchased cattle differed (P>.10) amonglengths of morning grazing. Conversely,SEKES steer weights increased with lengthof morning grazing such that steers weighedat 9 a.m. weighed 14.3 lb more (P<.10) thanthose weighed at 6 a.m. Because steersstarted grazing at approximately 6 a.m.,waiting until 9 a.m. gave them 3 hours togain fill. Weight changes from shrunk weightwere greater (P<.10) for steers from SEKESthan for purchased steers at the 7 a.m. and 9a.m. weighings and tended (P>.10) to begreater for SEKES steers at 6 a .m. and 8 a.m.

weighings. These values represe n t fill and theability of the cattle to regain fill following ashrink. The reason for the differentialresponse between cattle sources probably canbe attributed to cattle disposition. Purchasedsteers were difficult to manage, were ex-tremely excitable when weighed, and did notappear to settle into their normal routinerapidly following handling. The SEKESsteers were calm, moved quietly through theweighing facilities, and resumed a normalroutine rapidly following handling. This isthe most probable reason for the increased fillacquired during the intensive weighing peri-od.

Rate of cattle shrink throughout the dayalso was affected by length of morninggrazing (Table 2). Steers allowed to grazefor 3 h before being removed from pastureshrank .86 %/h less during the first 2.2-2.6 hfollowing removal from pasture than steersnot allowed to graze. Steers allowed tograze for 3 h shrank at a faster rate (%/hour)during the ensuing 1.9 to 2.7 h period, butcumulative rate of shrink at any length oftime following removal from pasture waslowest (P<.05) for steers all owed to graze for3 h prior to removal from pasture. Totalshrink at 3 p.m. was 2.9% less (P<.05) andrate of shrink was .19 %/h less (P<.05) forsteers allowed to graze for 3 h comparedwith those removed from pasture at the timegrazing began.

Table 1. Average Full Weight (lb) and Weight Change from a 16-hour Shrunk Weight

of Two Cattle Sources following Different Lengths of Morning Grazing onSmooth Bromegrass Pastures

Pasture Removal Time Item Source 6 a.m. 7 a.m. 8 a.m. 9 a.m.

Average weight, lb Purchased 669.8 665.6 674.8 666.6d d cd d

SEKES 680.7 683.9 686.6 695.0bc b ab a

Weight change, lb Purchased 25.5 21.3 30.5 22.3c c bc c

SEKES 31.3 34.5 37.2 45.6bc b ab a

Means for average weight (both sources) or weight change (both sources) without aabcd

common superscript differ (P<.10).


56

Lasalocid supplementation did not affect(P>.10) rate of shrink.

Examples of the economic impact of thisinformation are shown in Table 3. Example1 is for 20 steers gathered at different timesand sold at the local auction at 3 pm.Example 2 is for a group o f 432 steers loadedunder different scenarios and sent to a feedlotin western Kansas. A

sale price of $80/cwt was assumed, althoughsome price differential might occur becauseof cattle weight. Data gathered from thisstudy indicate that cattlemen could add over$26/head to the value of steers sold at a localauction or over $11/head to the value ofsteers loaded off of pasture and sold towestern Kansas feedlots.

Table 2. Rate of Shrink (%/hour) by Steers Gathered from Past ure following DifferentLengths of Morning Grazing on Smooth Bromegrass Pastures

Pasture Removal Time Mineral Item Period 6 a.m. 7 a.m. 8 a.m. 9 a.m. Lasal. Cont.a

Shrink, %/hour 1 1.25 1.19 1.05 .39 .91 1.03b c c c d

Shrink, %/hour 2 .61 .96 .17 .94 .68 .66f d c e c

Shrink, %/hour 1-2 .89 1.08 .71 .64 .81 .85cd c de e

Shrink, %/hour 3 .16 .02 .59 .15 .19 .26g d d c d

Shrink, %/hour 1-3 .67 .72 .67 .49 .62 .67c c c d

Total shrink, % to 3 pm 6.2 5.9 5.0 3.3 4.9 5.3h c cd d e

Total shrink, %/hour to 3 pm .69 .71 .67 .50 .62 .67c c c d

Periods are designations for times following removal from pasture . Period 1 is the first 2.2-a b

2.6 hours following removal from pasture, except for steers removed at 8 a.m. For thosesteers, period 1 was 3.4 hours . Means for pasture removal time within the same row withoutcde

a common superscript letter differ (P<.05) . Period 2 is the next 1.9-2.7 hours following periodf

1. Period 3 is the next 1.9 to 2.2 hours following period 2 . Total % shrink is based on theg h

weight measured immediately upon removal from pasture and water and weight measured atapproximately 1500 hours.

Table 3. Examples of the Effect of Different Lengths of Morning Grazing Allowanceon Cattle Value

Example 1 - 20 steers gathered from pasture at different times and sold at local auction at 3p.m.

Pasture Removal Time 6 a.m. 7 a.m. 8 a.m. 9 a.m.

# head 20 20 20 20Off pasture weight, lb 681 684 687 695Shrink, % 6.2 5.9 5.0 3.3Sale wt., lb 639 644 653 672Average value, $/head $511.20 $515.20 $522.40 $537.60a

Example 2 - 432 steers loaded off of pasture. Group 1 h a s all steers in one group and removedfrom pasture starting at 6 a.m. and loaded at a rate of one truck every 30 minutes. Group 2 has432 steers divided onto three pastures and gathered at either 6, 7:30, or 9 a.m., with half loadedimmediately and half loaded 30 minutes later.

Group 1 Group 2Depart Arrive Depart Arriveb

Average weight, lb/head 671 634 685 651Average value, $/head $536.80 $548.00a

Total value is based on total sale weight multiplied by $80/cwt.a

Arrival weight at a western Kansas feedlot after an 8-hour transit time.b


Appreciation is expressed to the following Kansas cattle breeders who assisted in this1

survey: Hubert Charolais, Monument; Green Garden Angus, Ellsworth; Gold Genetic Breeders,Phillipsburg; Dickinson Simmentals, Gorham; Thompson Cattle Company, Plainville; SchillingLimousin, Edson; Judd Ranch, Inc., Pomona; Gardiner Angus, Ashland; Stielow Angus, Paradise;BBB Charolais, Oakley; Runft Charolais, Scandia; RX Cattle Company, Hays; and JamisonHerefords, Quinter.

57


COMMERCIAL CATTLE PRODUCERS:BULL SELECTION CRITERIA 1

D. D. Simms, J. M. Geske, and R. P. Bolze

Summary

A survey of 312 commercial cattleproducers was conducted to determine therelative importance of selection criteria usedin buying bulls. Calving ease was a majorconsideration of a high percentage ofproducers, and individual performance wasbeing emphasized more than expectedprogeny differences (EPDs). Only 23% of theproducers included EPDs in their first threeselection criteria. Visual app raisal focused onstructural soundness, length, and muscling.

(Key Words: Bulls, Selection, Breeding,Expected Progeny Differences.)

Introduction

Many traits are of importance to thecommercial cattle industry, and the relativeimportance of specific traits tends to shift asthe industry changes. Understanding therelative ranking of traits by commercialproducers and the information they are usingto evaluate bulls has potential value forpurebred breeders and Extension specialists.Consequently, a survey was conducted inearly 1993 to assess current emphasis onselection criteria. Additionally, producerswere asked to give the strengths andweaknesses of the breeds that they were

using to determine current perceptions ofcommon beef breeds.


A questionnaire was maile d to over 1,000producers who purchased a bull in 1993.Buyer lists were provided b y 13 Kansas cattlebreeders and buyers at both the Beloit andPotwin bull sales. Breeds representedincluded Angus, Simmental, Charolais,Gelbvieh, Red Angus, Salers, Limousin, andHorned Hereford. Over 400 hundredquestionnaires were returned, with 312representing commercial producers. Becausethe criteria emphasized by commercialproducers were of primary interest, thequestionnaires returned by purebred buyerswere not included in the analysis.


Producers were asked to rank ( in order ofimportance) the factors considered inpurchasing a bull. Table 1 shows the relativeranking of types of information available tocommercial producers. Calving ease scorewas listed most commonly as the firstcriterion, and almost one-half of theproducers had it in their first three criteria.This result was interesting, considering thatonly the Simmental and Gelbvieh breedscurrently provide calving ease scores, and


58

these breeds accounted only forapproximately one-th ird of the bull purchasesrepresented in the survey. The relatively lowlevel of emphasis on expected progenydifferences (EPDs) indicated that producersweren't using the most accurate selectioncriteria available. Relative ranking for alltraits was similar across breeds, with theexception that buyers of Charolais andHorned Hereford bulls placed much lessemphasis on EPDs than buyers of Angus,Simmental, and Gelbvieh bulls. Buyers ofCharolais bulls emphasized birth weight andcalving ease much more than buyers of anyother breed, whereas buyers of HornedHerefords placed more emphasi s on breederreputation.

Table 2 summarizes the relative rankingof visual appraisal criteria. Structuralsoundness, length, and muscling were mostoften included in the first three criteria.

Performance information most oftenutilized is summarized in Table 3. Birthweight and birth weight EPD were the majorperformance items considered by producers.This emphasis indicates a shift from a similarsurvey conducted in 1981 (1982 Cattlemen'sDay), in which growth trai ts received primaryemphasis. The relative low ranking ofmaternal and milk EPDs was al so interesting,given the economic importance of thesetraits. Actual performance of the bull, i.e.,actual birth weight and weaning weight, wereutilized more than their corresponding EPDs.Studies have shown that EPDs are moreaccurate predictors of progeny perfor-

mance than the individual's actual perfor-mance. Therefore, producers should em-phasize EPDs more than ac tual performance.

Producers also were asked to indicatetheir direction with respect to cow size. Ofthose that responded, 78% wished to main-tain the size (weight) of their cows at currentlevels, whereas 7% wanted to increase sizeand 15% decrease size. Correspondingly,41% wanted to increase the milking ability oftheir cow herd, whereas 58% were contentwith current levels, and the remaining 1%wanted to decrease milk production.

Another question addressed producers'attitudes about the use of crossbred orcomposite bulls. Forty-six percent indicatedthat they would use them, whereas 54%indicated that they would not. The mostcommon reason given for not using acrossbred or composite bull was a concernabout the lack of predictabil i ty and uniformityof the offspring.

Seventy-four percent expressed a needfor across-breed EPDs, with breed compari-sons given as the main reason. The 26% thatdidn't indicate a need believed that across-breed EPDs would not be accurate andwould be confusing.

As a final part of the survey, producerswere asked to indicate the perceivedstrengths and weaknesses of the breeds thatthey were currently using. The three mostcommonly mentioned strengths and weak-nesses for each breed are shown in Table 4.


59

Table 1. Selection Criteria Utilized by Commercial Producers

FactorFirst Criterion,

%Included in First 3

Criteria, %

Calving ease score 25 49

Frame score 12 20

Birth weight 11 39

Conformation/visual appraisal 11 24

Expected progeny differences 9 23

Disposition 7 31

Breeder reputation 5 13

Weaning weight 4 32

Yearling weight 4 19

Structural soundness 4 16

Price 3 12

Color 1 5

Dam's functional traits 1 5

Pedigree 1 4

Polled/horned 0 5

Table 2. Ranking of Visual Criteria Emphasized by Commercial Producers



Criteria, %

Structural soundness 21 43

Disposition 17 29

Length 16 41

Frame score 12 33

Weight 12 26

Muscling 10 39

Straight top line 3 19

Smooth shoulder 3 15

Masculinity 2 7

Color 2 6

Large testicles 1 19


60

Table 3. Ranking of Performance Criteria Emphasized by Commercial Producers



Criteria, %

Birth weight and ratio 35 51

Birth weight EPD 15 43

Weaning weight and ratio 11 38

Weaning weight EPD 10 32

Yearling weight EPD 10 26

Direct calving ease EPD 6 27

Yearling weight and ratio 5 33

Maternal weaning weight EPD 3 7

Weight per day of age 2 12

Average daily gain 1 9

Milk EPD 1 9

Maternal calving ease EPD 1 9

Table 4. Breed Strengths and Weaknesses Indicated by Commercial Producers1

Breed Strength% of

Responses Weakness% of

Responses

Angus Maternal/milking ability 36 Slow growth rate 21Calving ease 32 Disposition 14Carcass quality 22 Too small framed 10

Red Angus Maternal/milking ability 24 Slow growth rate 26Color 20 Small framed 10Calving ease 18 Lack of availability 6

Simmental Growth rate 82 Too large framed 34Maternal/milking ability 24 Calving difficulty 25Frame size 8 Color/dilution gene 10

Charolais Growth rate 70 Calving difficulty 37Buyers' demand 14 Lack of milk/maternal 20Frame size 10 Too large framed 17

Gelbvieh Maternal/milking ability 63 Calving difficulty 20Growth rate 45 Too large framed 10Disposition 15 Lack of eye appeal 9

Hereford Disposition 34 Eye problems 34Easy keepers 28 Poor milkers 21Growth rate 10 Lack of buyer demand 9

Limousin Muscling 31 Poor milkers 28Lean carcass 28 Disposition 25Calving ease 16 Slow growth rate 19

Salers Calving ease 84 Disposition 53Lean carcasses 16 Slow growth rate 16Maternal/milking ability 16 Lack of buyer demand 11

Responses per breed were as follows: A N = 186, RA = 51, SM = 119, CH = 71, GV = 87, HH = 47, LM = 32 and1

SA = 19.


Department of Agricultural Economics.1

61


ECONOMIES OF SIZE FOR KANSASBEEF COW PRODUCTION

M. R. Langemeier and T. C. Schroeder 1

Summary

Economies of size measure the impact ofincreasing the size of operation on averagecost of production. Economies o f size existif average total cost decreases as sizeincreases. Enterprise data from producersenrolled in the Kansas Farm ManagementAssociations in 1992 were used to empiricallyestimate economies of size for beef cowenterprises. Results indicate that economiesof size exist for beef cow enterprises.Average total cost per head declined as thenumber of beef cows increased.

Substantial variability in costs of pro-duction between producers also were docu-mented. Costs of production betweenproducers of a given size varied considerablymore than changes in cost of productionattributed to size alone. S maller than averagebeef cow enterprises can compete in the1990's, if they are cost competitive. Inaddition to size, feed costs, fixed costs,production efficiency, and sale prices ofcalves were important factors affecting theprofitability of beef cow enterprises.

(Key Words: Economies of Size, Cost ofProduction, Profitability, Cow/Calf.)

Introduction

Economies of size measure the rela-tionship between the size of operation(number of cows) and the average cost ofproduction or break-even price. If averagetotal costs decline rapidly as firm size

increases, the industry may become moreconsolidated as firms increase size to reduceaverage costs. Conversely, if average totalcosts are similar for firms of different sizes,incentive for consolidation may be less.

Economies of size measures can be usedto determine whether it would beadvantageous for farms to become larger.Economies of size can result from quantitydiscounts for inputs, from an increase inefficiency as size increases, or from adoptionof capital-intensive technology. Additionally,as a producer increases the size of anenterprise, fixed costs such as unpaidoperator labor, depreciation, and interest arespread over more units and fixed costs perunit decline. This research was conducted toexamine economies of size for beef cowoperations in Kansas using data from theKansas Farm Management Associations.Additionally, differences in cost ofproduction among producers were evaluatedto determine which factors had the greatestimpact on profitability.


Enterprise data from 171 beef cowproducers enrolled in the Kansas FarmManagement Associa tions in 1992 were usedin this study. Enterprise data included thesize of the operation, gross income, costs ofproduction, profitability, and productivity.The average farm in the sample had 101 beefcows, with a range of 12 to 465.


62

Productivity was measured as hundred lb(cwt) produced per cow, which included calfand breeding livestock sales as well asinventory changes. Production costs andprofits were expressed on both per cwtproduced and per head bases.

Variable cost categories included hiredlabor, repairs, interest paid, feed, veterinaryexpenses, utilities, fuel, and miscellaneouscash expenses. Feed costs included raisedand purchased feed and pasture expenses.All feed costs were measu red using economiccosts of production. Thus, owned pastureland was charged an opportunity cost equalto the rented value of the pasture. Raisedfeed was priced according to prevailingmarket prices. Fixed cost c ategories includedunpaid operator labor, depreciation andinterest on buildings and equipment, and realestate taxes.

The gross margin ratio, indicating theamount of variable costs incurred per dollarof revenue generated, was used as a measureof economic efficiency. The gross marginratio was calculated by dividing variable costper cwt by gross income per cwt. A lowerratio indicates that a firm is more efficient.

A cost function was estimated by re-gressing average total cost per cwt on sizevariables. If economies of size exist, the sizevariables in this regression would besignificantly different from zero.

This study also used data from the KansasFarm Management Associations to separateproducers into top and bottom one-thirdprofit groups. Return above total cost wasused to separate the 171 prod ucers into profitgroups.


Figure 1 presents the average total costcurve (represented by the solid line) for 171beef cow operations in the Kansas FarmManagement Associations in 1992. Eachtriangle in Figure 1 represents the averagetotal cost per cwt for a specific farm.Average total cost was significantly

correlated with the size of the operation(P<.05). However, as evident from thevariability in costs presented in Figure 1, sizewas not the only factor influencing cost. Theaverage total cost curve did not reach aminimum over the range of the data.

Using the average total cost curve inFigure 1, farms with 25 and 50 beef cows hadbreak-even prices that were 12% and 4%above that of a farm with 100 beef cows.Farms with 200 and 300 beef cows hadaverage total costs 4% and 6% below thoseof a farm with 100 beef cows.

Variable costs were not significantlydifferent across farm size. Thus, the costadvantages of large farms were related tounpaid operator labor costs and depreciationand interest on fixed assets.

As indicated by Figure 1, tremendousvariability occurred in average total costsamong operations. Differences in costs ofproduction for farms of the same size weremuch wider than differences in costs ofproduction between large and small farms.

Table 1 presents financial and productionfactors for the average farm, compared tothose in the bottom and t op one-third. Farmsin the top one-third averaged about 30 cowsmore than farms in the bottom one-thirdprofitability group. However, farms of allsizes occurred in both groups.

Gross income for producers in the topone-third profit group was about $6.80 percwt higher than gross income for producersin the bottom one-third profit group. Saleprice and sale weight were similar for the twoprofit groups. Cwt produce d per cow, on theother hand, was relatively higher forproducers in the top one-third profit group,which resulted from a larger calf crop. Thegross margin ratio was significantly lower forproducers in the top one-third group than forthose in the bottom one-third profit group.

Costs of production were significantlylower for producers in the top one-thirdprofit group. Their total costs of production


63

were about $147 per cow lower than thosefor producers in the bottom one-third. Alarge proportion (46%) of the difference incost of production between p rofit groups wasattributable to fixed costs. Another 37% ofthe difference was attributable to feed costs.Feed costs per head were about $55 lowerfor the producers in the top one-third group.The remaining 17% of the difference in costswas attributable to variable costs other thanfeed.

Using the above information, we identi-fied five critical factors affecting the profit-ability of the beef cow enterprise:

(1) size of the herd,(2) feed costs,(3) fixed costs, (4) pounds of beef produced per cow,

and(5) sale price of calves.

For any size of operation, it is imperative tocontrol production costs. Even with higherthan average performance, high-cost pro-ducers are at a competitive disadvantage.

Table 1. Selected Financial and Production Factors for Beef Cow Producers inKansas

BottomOne-Third(57 Farms)

Average(171 Farms)

TopOne-Third(57 Farms)

Financial Factors ($/Cwt.) Gross income 73.85 77.52 80.66 Sale price of calves 86.18 86.29 85.58 Feed cost 50.18 43.66 36.10 Variable cost 72.49 62.97 52.27 Total cost 107.40 89.97 72.54 Gross margin ratio1 .99 .82 .65Financial Factors ($/Cow) Gross income 409.50 447.45 497.02 Feed cost 277.85 249.48 223.66 Variable cost 400.42 359.37 321.28 Total cost 592.66 512.39 445.73 Return above variable cost 9.08 88.08 175.74 Return above total cost -183.16 -64.94 51.29Production Factors Number of cows 87 101 118 Sale weight of calves, lb 568 564 575 Cwt. produced per cow 5.63 5.85 6.25Variable costs ÷ revenue generated.1

Source: Kansas Farm Management Associations.


Figure 1. Average Total Cost per Cwt for Beef Cow Operations in Kansas, 1992

64


Southwest Kansas Research Extension Center, Garden City, KS1

65


EFFICACY OF USING PARASITIC WASPS TOCONTROL STABLE FLIES IN KANSAS FEEDLOTS

G. L. Greene and J. E. Cilek1 1

Summary

Release of parasitic wasps has resulted instable fly reductions averaging 28, 42 and38% for 1991, 1992, and 1993, respectively,with considerable variation from feedlot tofeedlot. Costs for parasites plus samplingaveraged $.23, $.32 and $.26 per animalduring 1991, 1992, and 1993, respectively.Because stable flies are estimated to causelosses of $5.00 to $30.00 per animal, thesecosts are very reasonable.

(Key Words: Cattle Feedlot, Stable Fly, FlyParasites, Pest Management Costs.)

Introduction

Research on feedlot fly reduction with flyparasite releases has shown considerablepromise since 1991. Spalangia nigroaenea,a fly parasite collected in southwest Kansas,has been used in this program. It attacksstable fly pupae and prevents fly emergence.The use of parasites to replace insecticides isneeded because flies have become resistant tomany of the available insecticid es, and insecti-cides are becoming less availab le for livestockuse. To determine the effica cy of substitutingbiological control methods for chemicalapplications, levels of fly reduction andrelated costs must be known.


Costs for parasites and sampling fees arebased on 4, 18, and 17 feedlots for 1991,1992, and 1993, respectively. Four to sixadditional feedlots, where parasites were notreleased, were sampled each year as controls.

Adult fly numbers were monitored byplacing Alsynite sticky t raps at the margins ofeach feedlot. Each week, the number ofstable flies trapped was recorded, and thesticky covers on the traps were replaced.

Costs reported reflect th e average paid bycooperating feedlots. A sampling fee wasestablished to cover sampling costs. This feediffered each year and from feedlot tofeedlot, depending on size. During 1991,feedlots were charged for parasites only . In1992, a sliding scale was established withsmaller feedlots paying more per animal thanlarger feedlots. During 1993, $.10 per animalwas charged with a maximum of$5,000/feedlot, which resulted in a cost ofless than $.10 per animal for the largefeedlots.


The costs per animal showed con siderablevariation (Table 1) ranging from $.03 to$1.55. This difference was related to


66

cleanliness and/or excess fly breeding areas.During 1993, the maximum sampling costsincreased because of an extreme amount ofwet manure. Average sampling and totalcosts decreased from 1992 to 19 93 as a resultof delayed fly development during 1993.Parasite costs remained at $.08 per animalduring 1992 and 1993. A total cost of $.26per animal for 1993 was very reasonableconsidering the wet, cool season.

Numbers of stable flies caught weregreater during 1993 than 1992 (Table 2),even though the populations were greater in1992. This may have been the result of thesticky trap covers holding flies better during1993. The relative costs for feedlots withlow and medium fly populations switchedfrom 1992 to 1993. The larger feedlots heldboth parasite and total costs per animal downfor the medium level in 1992 and the lowlevel in 1993. The single feedlot wit h a lowfly level and costs of $.87 had a large flybreeding area where high numbers ofparasites were released. Fly countsdocumented that large parasite releases heldthe fly numbers down, even in a heavilyinfested feedlot.

Cost of parasites was lower for thefeedlots with a high fly leve l during 1993 than1992 ($.27 vs $.42 per animal, respectively).Most of this cost reduction was due to thelater buildup of stable flies during 1993.

In 1982, the average cost for parasiteswas $.05 per animal. The cost rose to $.10per animal during the mid-19 80s and to about$.30 during the late 1980s. Consequently,the current charge of $.26 per animal for theKSU fly management experimental programappears reasonable. However, the costs of$1.34 and $1.55 per animal for the mostexpensive feedlots are exces sive. These costssuggest that sanitation improvement shouldprecede fly parasite releases. Additionally,we should note that we have observed lowerfly populations in feedlots wher e S.nigroaenea were released during previousyears, suggesting carryover benefit.

The average reduction in stable fly popu-lations measured by Alsynite traps is shownin Table 3. These reductions roughly parallelthe rates of parasitism for 1991 and 1992.Parasitism data for 1993 ar e not yet available.

Table 1. Costs per Animal for Stable Fly Management in Cattle Feedlots with ParasiteReleases, 1991-93

No. of No. of Cost, $ per Head

Year Feedlots Cattle/Lot (1000's) Parasites Sampling Total

1991 4 54(4.2-100)a

.08(.05-.10)

.18(.07-1.55)

.26

1992 18 48.9(2.2-100)

.08(.03-.30)

.24(.06-1.10)

.32

1993 17 45.4(2.2-100)

.08(.05-.10)

.18(.07-1.55)

.26

Numbers in parentheses are the range from low to high.a


67

Table 2. Comparison of Fly Level or Degree of Sanitation Relative to Costs for Parasites andSampling during 1992 and 1993

Fly No. of No. of Cost, $ per Head

levela Year Lots Cattle/Lot (1000's) Parasites Total

Low

(45-53)b 92 5 9.8(2.2-22.3)

.26 .37(.27-.52)

(104-126) 93 6 34.7(2.2-100)

.13 .18(.12-.87)

Medium

(107-138) 92 7 45.6(9-100)

.18 .24(.09-1.15)

(143-170) 93 5 23.0(12-35)

.22 .29(.20-.50)

High

(184-253) 92 6 20.0(7-37)

.42 .54(.33-1.34)

(197-469) 93 6 14.9(4.2-41)

.27 .37(.25-1.55)

Flies per Alsynite trap per daya

Numbers in parentheses are the range from low to high.b

Table 3. Stable Fly Populations in Parasite Release and Control Feedlots

Stable Flies per Trap per Week

Feedlot Treatment 1991 1992 1993

Nonrelease 37 200 251

Release 27 116 156

% Reductions 28 42 38


Department of Statistics.1

68


IN VITRO DRY MATTER DIGESTIBILITY OFSELECTED FORAGE SORGHUM SILAGES AS

INFLUENCED BY PLANT PARTS

R. N. Sonon, Jr., K. K. Bolsen, B. E. Brent,L. H. Harbers, and J. E. Boyer, Jr.1

Summary

Eleven forage sorghum cultivars and onegrain sorghum hybrid were used to determinethe effect of individual plant parts on in vitrodry matter digestibility (IVDMD) of sorghumsilage. IVDMD was h ighest for the head andlowest for the leaf sheath. When head andleaf blade parts were added to whole-plantmaterial, IVDMD increased. When leafsheath and stalk parts were added, IVDMDdecreased, with the greatest decrease for leafsheath. These results are consistent with anearlier study in our laboratory.

(Key Words: Sorghum, Silage, Plant Part,Digestibility.)

Introduction

We have shown in previous reports(KAES Reports of Progress 568, p age 12 and623, page 65) the tremendous variation insilage nutritive value traits among foragesorghum hybrids and va rieties. Huge cultivardifferences also occur in the proportion ofplant parts (i.e., head, leaf blade, leaf sheath,and stalk) and their digestibility. Ourobjective was to continue to document theeffect of the individual plant parts on thenutritive value of forage sorghum silages.


Eleven forage sorghum cultivars and onegrain sorghum hybrid (Table 1) were grownunder dryland conditions near the KansasState University campus in 1989. The

agronomic and silage quality results werepresented in the KAES Report of Progress623, page 65. In addition, 10 whole plants ofeach cultivar were taken at the late-doughstage of kernel maturity and separated intohead, leaf blade, leaf sheath, and stalk. Theseparated parts were chopped by hand with aknife to a length of about .4-inch.Approximately 400 g of each chopped plantpart was placed in a nylon bag and ensiled inthe center of the forage mass whole-plantmaterial from the same cultivar in pilot-scalesilos made from polyethyl ene-lined, 55-gallonbarrels. The silos were opened 90 dayspostfilling, the ensiled pl ant parts were recov-ered, and the surrounding silage wassampled. The plant part and whole-plantsilage samples were dried for 72 h andground in a Wiley mill.

IVDMD of the ensiled plant pa rts, whole-plant silages, and reconstituted silages for the12 sorghum cultivars were determined by theartificial rumen method of Tilley and Terry.Reconstituted silages were prepared bycombining the four ensiled plant partsaccording to their respective proportions inthe original whole-plant DM (Table 1). Theweighted sum of the IVDMD of the ensiledplant parts also was determined andcompared to the IVDMD of the whole-plantsilage.

For five of the silages, plant parts wereexchanged with whole-plant material in .05 gincrements until all .5 g of the artificial rumensubstrate was made up of the plant part. Therumen fluid used was from a fistulated, dry,


69

dairy cow fed a ration containing 80% foragesorghum silage on an as-fed basis.


The mean pH, DM content, and IVDMDfor the ensiled plant parts are presented inTable 2. All three measurements weresignificantly different among the four plantparts. The head, which was the driest, hadthe highest pH, whereas the stalk, which wasthe wettest, had the lowe st pH. IVDMD washighest for the head, whereas the leaf sheathwas the least digestible. This trend occurredin all 11 grain-producing cultivars (data notshown).

The mean IVDMD for the whole-plantmaterial was 57%, that for the reconstitutedsilages was 60%, and that for the sum

of the ensiled plant parts was 58%. Differ-ences between all three means were signifi-cant. The IVDMDs for both the reconsti-tuted silages and sum of the ensiled plantparts were higher than the IVDMD of thewhole-plant silages for all 12 cultivars (datanot shown).

As shown in Figure 1, as head materialwas increased, digestibil ity increased. As leafsheath material was increased, IVDMDdecreased substantially. Leaf blade and stalkmaterial had less effect on digestibility. Theslope data in Table 2 show the results ofpooling plant parts across cultivars andtreating the data by regression. Positivevalues indicate that IVDMD increased as theplant part was added, and negative valuesindicate that IVDMD decreas ed. Thus, muchof the difference in digestibility betweenforage sorghum cultivars probably can beexplained by the percentage of dry matterfrom leaf sheath.

Table 1. Plant Part Proportions for the 12 Sorghum Cultivars

Plant Part2

Cultivar1 Head Leaf blade Leaf sheath Stalk

DeKalb 42Y 69.7 12.1 8.3 9.9Oro Kandy Kane 60.8 11.0 6.8 21.4Rox Orange 58.3 9.9 6.7 25.1DeKalb FS5 45.0 15.9 8.7 30.4Pioneer 947 48.4 17.8 10.0 23.8Northrup King 300 45.5 21.7 12.8 20.0DeKalb FS25E 22.6 22.6 11.2 43.6Funk's 102F 39.4 20.3 13.0 27.3Funk's G1990 0 34.0 15.7 50.3GA T-E Silomaker 33.4 19.5 14.0 33.1Garst 333 31.3 19.4 11.8 37.5Seed Tec Hi-Energy II 33.1 18.1 9.8 39.0

Mean 40.6 18.5 10.8 30.1

DeKalb 42Y is a grain sorghum hybrid and GA T-E is Golden Acres Taylor-Evans.1

Plant part proportions are expressed as a % of the whole-plant DM.2


Table 2. Mean pH, DM Content, IVDMD, and Slope Parameter Estimates for theEnsiled Forage Sorghum Plant Parts

Plant Part pH DM Content IVDMD Slope1

% %

Head 4.42a 53.9a 64.8a 16.2a

Leaf blade 4.32a 28.2b 57.1b 4.2b

Leaf sheath 3.92b 25.0b 46.4d -23.4d

Stalk 3.75c 19.0c 53.7c -3.5c

SE .047 1.21 .62 1.80abcdMeans within a column with unlike superscripts differ at P < .051Change in IVDMD per g increase in the respective plant part in the artificial rumensubstrate.

Figure 1. Influence of Plant Parts on IVDMD of the Five Forage Sorghum Hybrids

7 0


71


EFFECT OF GRAIN CONTENT ON THE NUTRITIVEVALUE OF WHOLE-PLANT CORN SILAGE

R. N. Sonon, Jr., B. S. Dalke, D. L. Holthaus,M. A. Young, L. Pfaff, and K. K. Bolsen

Summary

This experiment was conducted todetermine the effect of grain content on thenutritive value of corn silage. Whole-plantsilage dry matter (DM) increased, whereasneutral detergent fiber (NDF) and aciddetergent fiber (ADF) contents decreased asthe level of grain increased from 0 to 65% inthe reconstituted, whole-plant, corn silages.Using sheep as a model, vo luntary DM intakeand DM and organic matter (OM) digest-ibility increased, but crude protein (CP) andADF digestibilities decreased linearly as graincontent increased from 0 to 52.5%. Our re-sults indicate that the optimum level of grainin whole-plant corn silage to maximize thenutritive value of a high silage-based rationwas about 52.5%.

(Key Words: Corn, Silage, Grain Content,Nutritive Value.)

Introduction

Typically, corn hybrids are selected forgrain yield potential and not necessarily fortheir silage traits. There is a long-standingbelief that the nutritive value of corn silageincreases as the proportion of grain in thewhole-plant silage increases. However, intwo recent studies, we found that highergrain-containing corn sil ages were not alwaysnutritionally superior to those with less grain(KAES Reports of Progress 592, page 110,and 678, page 19).

We compared all-stove r silage with silagereconstituted to contain 27.5 to 60% grain.


Cargill 6227 corn hybrid was planted onMay 18, 1992 near the Kansas StateUniversity campus at Manhattan, on a Read-ing silt loam soil at a seeding rate of ap-proximately 27,110 plants/acre. Anhydrousammonia was applied preplant at 100 lb/acre,and 2.0 lb/acre of Ramrod-atrazine wasapplied at planting time. The hybrid wasgrown under irrigation and harve sted at about85% milk line stage of kernel maturity.

Three days before harvest, 30 wholeplants were taken randomly from a crosssection of the 118 × 690 ft experimental plot.The fresh whole plants were weighed andseparated into grain, cob, and stoverfractions. Fresh weights of the separatedparts were recorded, and samples of the partswere dried to determine plant part propor-tions in the whole-plant DM.

The remaining plants were harvested onSeptember 13, 1992. The ea rs were removedby hand, leaving the stover portion of theplant (including the husk). The ears andstover were chopped separately with aFieldqueen, precision, forage harvester. Thechopped ears and stover were combined toprovide 27.5, 40.0, 52.5, and 65.0% grain inthe reconstituted, whole-plant material (DMbasis), and mixed in a mixer wagon. Thesilages, including an all-stover silage, weremade in polyethylene-lined, 55-gallon barrels.

After about 90 days of storage, a vol-untary intake and digestion trial was con-ducted to determine the nutritive value of thefive silages. Because of the limited amountof silage we could make in barrels, sheep


72

were used as model animals. Thirty wethersheep were blocked by weight andindividually housed in metabolism crates.The five silages were assigned randomly ineach block. Rations contained 90% silageand 10% supplement (DM basis) and werebalanced to 11.5% crude protein (DM

basis) with ground corn grain, soybean meal,and urea. Rations supplied equal amounts ofcalcium, phosphorus, and vitamins A, D, andE. The trial consisted of 7-day adaptation, 7-day voluntary intake, 2-day transition, and 6-day total fecal collection phases. Duringtransition and collection phases, all sheepwere fed 90% of their mean voluntary DMintakes.

Table 1. pH, DM Content, and Chemical Composition of the All-Stover and FourReconstituted, Whole-Plant, Corn Silagesa

Grain pH DM CP NDF ADF

% % )))))))% of the silage DM)))))))

0 3.53 27.1 6.3 66.0 43.2

27.5 3.58 28.8 6.8 48.1 37.2

40.0 3.65 31.2 7.4 44.0 29.4

52.5 3.71 35.9 7.8 40.7 25.4

65.0 3.98 40.5 7.6 38.1 20.1

DM = dry matter, CP = crude protein, NDF = neutral detergent fiber, ADF = acid detergenta

fiber.

Table 2. Chemical Composition of the Rations Fed to Sheep in the VoluntaryIntake and Digestion Trial a

Grain OM CP NDF ADF

% ))))))))))))% of the ration DM)))))))))))

0 90.9 12.0 60.8 39.5

27.5 91.3 11.5 45.0 34.2

40.0 92.9 11.0 41.0 27.1

52.5 93.9 11.0 37.8 22.5

65.0 94.8 11.2 35.6 18.6

DM = dry matter, OM = organic matter, CP = crude protein, NDF = neutral detergent fiber,a

ADF = acid detergent fiber.

Grain content was used to predict vol-untary DM intake; digestibilities of DM, CP,NDF, and ADF, and percent digestibleorganic matter.


The pH, DM content, and chemicalcomposition of the five silages and chemicalcomposition of the five rations are presentedin Tables 1 and 2, respectively. All silageswere well preserved, as evidenced by low pHvalues. Silage DM and OM contents in-


creased, whereas NDF and ADF contentsdecreased with increasing levels of grain inthe reconstitute d silages. Crude protein con-tent increased as grain in the silage increased.

Voluntary DM intake and digestibilities ofDM, NDF, and ADF for the five silagerations fed to sheep are presented in Figures1 through 4, respectively. Digestibility of CPand percent digestible organic matter are notshown. Regression analyses indicated thatvoluntary DM intake; digestibilities of DM,CP, and ADF; and percent digestible organicmatter responded linearly to increasing graincontent in the reconstituted, whole-plantsilages. The greatest response to grainaddition occurred from 0 to 27.5% grain.Voluntary DM intake increased by 12.6%between the increments from 27.5 to 40.0and 40.0 to 52.5% grain in the silage. DMdigestibility increased by 2.8 and 4.7percentage units, when grain levels in the

silage were increased from 27.5 to 40.0% and40.0 to 52.5%, respectively. Crude proteinand ADF digestibilities decreased withincreasing grain content, whereas NDFdigestibility showed a quadratic response.Grain content had only a modest effect onthe digestibility of these nutrients.

The optimum level of grain in thereconstituted, whole-plant corn silages was52.5%, at which DM intake was highest(62.5 g/kg BW .75) and DM and OM digest-ibility approached their maxima (66.2 and68.2%, respectively), with only slightnumerical increases at 65.0% grain content.This is supported by the high predictivepower of grain content for percent digestibleOM (r2=.846) and DM digestibility (r2=.791).

Figure 1. Effect of Grain Content on Voluntary DM Intake of Sheep. MBW is BW .75

Figure 2. Effect of Grain Content on DM Digestibility in Sheep

73


Figure 3. Effect of Grain Content on NDF Digestibility in Sheep

Figure 4. Effect of Grain Content on ADF Digestibility in Sheep

7 4


Partial financial assistance was provided by Biotal, Inc., Eden Prairie, Minnesota.1

Former graduate student, current address: Visayas State Agricultural College, Baybay,2

Leyte, Philippines.

75


AGRONOMIC TRAITS AND GROWING CATTLEPERFORMANCE FOR WHOLE-PLANT CORN AND FORAGE

AND GRAIN SORGHUM SILAGES 1

B. S. Dalke, R. N. Sonon, Jr . , D. L. Holthaus,2

M. A. Young, L. Pfaff, and K. K. Bolsen

Summary

Agronomic and cattle performance traitswere measured for the following silages pro-duced in 1992: irrigated Pioneer 3377 corn,ensiled with or without Biotal® silage inoc-ulant; DeKalb 42Y grain sorghum; andCargill 200F, Pioneer 947, DeKalb FS-5 andFS-25E, and Northrup King (NK) 300 foragesorghums. All sorghums were grown underdryland conditions. The irrigated corn hadthe highest whole-plant dry matter (DM) andgrain yields, and NK 300 and DeKalb FS-5had the highest whole-plant DM yieldsamong the sorghums. NK 300 also had thehighest grain yield among the sorghums;DeKalb FS-5 and FS-25E had the lowest.Steers fed the irrigated corn silages had thefastest and most efficient gains, and the late-season forage sorghum, DeKalb FS-25E,produced the slowest and least e fficient gains.Inoculating the corn silage increased DMrecovery, fermentation efficiency, and steergain per ton of crop ensiled.

(Key Words: Silage, Corn, Sorghum,Growing Cattle.)

Introduction

Silage production in Kansas is primarilyfrom irrigated or dryland corns and drylandgrain and forage sorghums. In severalprevious studies, we have documented theeffects of growing condition, hybrid, stage ofmaturity, processing, grain addition, and

climate (i.e., growing season) on the yieldpotential and nutritive value of numerouscorn and sorghum silages. The objectives ofthis study were to compare both agronomictraits and cattle performance from silagesproduced in the 1992 growing season.


The crops were grown near the KansasState University campus during the 1992season. The eight silages included irrigatedPioneer 3377 corn (with or without Biotalsilage inoculant); dryland DeKalb 42Y grainsorghum; and Cargill 200F, Pioneer 947,DeKalb FS-5, Northrup King 300, andDeKalb FS-25E dryland forage sorghums.The two fields used were predominantlyReading silt loam soil. Prior to planting,anhydrous ammonia was applie d at 100 lb peracre for the irrigated corn and dryland grainsorghum, and 80 lb per acre for the fiveforage sorghums. The corn was harvested atthe 90% milk line stage of kernel maturity,and the six sorghums, at the very late-doughstage. All eight silages were made in 10 × 50ft concrete stave silos. The silos containingthe two corn silages were filled by thealternate load method.

The silos were opened on June 1 0 and 11,1993 and emptied at uniform rates during thenext 3 months. Silage samples were takenthree times weekly. Each silage was fed to16 yearling, crossbred steers (four pens offour steers per silage) in a 77-day growing


76

trial, which began on June 15, 1993. Thecomplete mixed rations were fed twice dailyto appetite and contained (DM basis) 89%silage and 11% supplement. Supplementswere formulated to provide rations of 12.0%crude protein, .50% calcium, and .30%phosphorus (DM basis); 250 mg of rumensinand 30,000 IU of vitamin A per steer daily.

For 5 days before the start of the growingtrial, all steers were limit-fed a foragesorghum silage ration to pr ovide a DM intakeof 2.0% of body weight. Steers then wereweighed individually on 2 consecutive days.For 3 days before the final weighing, thesteers were fed their respective silage rationsat a restricted DM intake of 2.0% of bodyweight. Then individual weights were takenon 2 consecutive days.


Agronomic performance and chemicalcomposition of the seven silage crops areshown in Table 1. The corn and DeKalb

FS-5 and NK 300 had the highest whole-plant DM yields per acre; the late-seasonforage sorghum (DeKalb FS-25E) had thelowest DM yield. Grain yields of the fiveforage sorghums were above average andwere highest for NK 300 and Pioneer 947.The CP values were lower and ADF valueshigher for the five forage sorghums than inprevious years (KAES Report of Progress678, page 16), which suggest s that all wereof lower than expected nutritional values.Gains and efficiencies were not related to thepercent grain in the silages but were closelyrelated to the silage ADF content.

Average daily gains and efficiencies ofgain (Table 2) were excellent for steers fedthe two corn silages and the DeKalb 42Ygrain sorghum silage. As expected, the cornsilages produced the fastest an d most efficientgains. Steers fed the grain sorghum silagehad the highest daily DM intake, whereasthose receiving the late-season foragesorghum, DeKalb FS-25E, had the lowestDM intake and slowest and least efficientgain. Gains and efficiencies were poorer forsteers fed the five forage

Table 1. Agronomic Performance and Chemical Composition of the Seven Crops and Silagesin 1992

1992 Whole-Plant Silageb

Crop, GrowingCondition, andHybrid

Plantingdate

Harvestdate

Plantheight,inches

DM,%

DM yield,tons/acre

Grainyield,

bu/acreaCP,%

ADF,%

Corn: irrigated

Pioneer 3377 May 11 Aug. 28 108 29.8 9.4 200 7.4c 24.2c

Grain sorghum: dryland

DeKalb 42Y June 9 Sept. 22 54 36.2 6.9 108 8.8 27.9

Forage sorghum: dryland

Cargill 200F June 12 Sept. 23 117 37.3 6.0 105 7.0 33.0

Pioneer 947 June 12 Sept. 29 123 35.1 6.8 133 7.9 32.9

DeKalb FS-5 June 12Sept. 28 115 32.0 7.6 96 7.7 36.5

Northrup King 300 June 12 Oct. 12 91 31.6 7.4 173 7.0 33.2

DeKalb FS-25E June 12 Oct. 22 125 29.7 5.5 98 6.3 39.8

Bushels/acre are adjusted to 14.5% moisture.a

CP = crude protein, ADF = acid detergent fiber. Both are reported on a DM basis.b

The Biotal-treated and untreated corn silages had similar CP and ADF contents and only the meanc

values are reported.


77

sorghum silages than for those fed the cornor grain sorghum silages.

Treating the corn silage with Biotal silageinoculant did not affect rate or efficiency ofgain. However, the inoculant increased DMrecovery by .9 percentage units compared tothe control (91.7 vs. 90.8% of th e crop DMensiled).

The inoculated silage also had a lower pH(3.72 vs. 4.02); more lactic acid; a higherlactic to acetic acid ratio (2.2 vs. 1.2); andless acetic acid, ethanol, and ammonianitrogen compared to the control silage.When the DM recovery and feed efficiencyresults were combined, the inoculated cornsilage produced 3.6 lb more steer gain per tonof crop ensiled than the control silage.

Table 2. Performance by Yearling Steers Fed the Eight Silage Rations in 1993

CornGrain

Sorghum Forage Sorghum

ItemInoculated(Biotal)

Control(untreated)

DeKalb42Y

Cargill200F

Pioneer947

DeKalbFS-5

NK300

DeKalbFS-25E

LSDa

(P<.05)

No. of steers 16 16 16 16 16 16 16 16 —

Initial wt, lb 570 572 570 568 572 575 564 567 —

Final wt, lb 808 811 769 711 731 719 731 711 71.0

ADG, lb 3.07 3.11 2.60 1.86 2.06 1.99 2.05 1.72 .3

Daily DM intake, lb 17.3 17.6 18.3 14.7 16.9 16.1 16.2 14.5 2.2

Feed/lb of gain, lbb 5.6 5.7 7.0 8.0 8.2 8.1 8.0 8.5 1.5

LSD = least significant difference. Means that differ more than the LSD are statistically different (P<.05)a

DM basis.b


The steers used in this trial and partial financial assistance were provided by Mr. Richard1

Porter, Porter Farms, Reading, KS.

78


EFFECTS OF SORGHUM HYBRID AND GRAINSUPPLEMENTATION ON THE UTILIZATION OF

SILAGE-BASED RATIONS FOR GROWING CATTLE 1

B. S. Dalke, K. K. Bolsen, R. N. Sonon, Jr.,M. A. Young, and D. L. Holthaus

Summary

Three whole-plant sorghum silages, eachwith or without 25% added rolled grainsorghum were fed to six medium-framed,ruminally cannulated steers in a 6 × 6 Latinsquare design. The grain sorghum silage ra-tions (DeKalb 42Y) had the highest DM,OM, and ADF digestibilities; the late-seasonforage sorghum silage rations (DeKalb FS25E), the lowest. Digestibility of NDFtended to be highest for the grain sorghumsilage, but starch digestibilities were notaffected by sorghum hybrid. Ruminalammonia, acetate, propionate, butyrate, andtotal VFA concentrations were highest forthe grain sorghum silage rations. Grainsupplementation increased DM and OMdigestibilities but had no effect on NDF,ADF, or starch digestibilities. Ruminal pHwas decreased, whereas VFA concentrationswere not affected by grain supplementation.The grain sorghum silage had the highestnutritive value, and the middle-season foragesorghum silage (DeKalb FS 5) was superiorto the late-season forage sorghum. Theseresults are consistent with several of ourprevious trials, which compared grain andforage sorghum silages for growing (back-grounding) cattle.

(Key Words: Silage, Forage Sorghum, GrainSorghum, Hybrid.)

Introduction

The wide ranges of plant height, seasonlength, DM content, and whole-pl ant DM andgrain yields contribute to the large variationsin nutritive values observed between foragesorghum hybrids and varieties (KAESReports of Progress 539, pages 167, 172, and177; 623, page 65; and 678, page 13).

We have reported previously that adding25% grain (DM basis) to sorghum silage-based rations improved both rate and effi-ciency of gain, particularl y the middle-season,moderate grain-content and late-season, lowgrain-content forage sorghum hybrids. Thepresent study continued to document theeffects of sorghum hybrid and grainsupplementation on nutrient dig estibilities andpassage rates and ruminal metabolism ofsilage-based rations fed to growing cattle.


Six medium-framed steers, fitted withruminal cannula and averaging 680 lb, wereutilized in a 6 × 6 Latin square design with a3 × 2 arrangement of treatments. We fedthree whole-plant silages (DeKalb 42Y grainsorghum and DeKalb FS 5 and FS 25Eforage sorghums), each with or without 25%added rolled grain


78

Table 1. Composition of the Sorghum Silages

ItemDeKalb

42YDeKalb

FS 5DeKalbFS 25E

DM, % 34.5 28.9 27.3

))))% on a DM basis))))

CP 8.8 7.7 6.3

NDF 47.8 55.5 54.5

ADF 27.9 36.5 39.8

Starch 45.3 39.7 30.5

Plant height, in 53 115 125

Grain, bu/acre 107 96 98

Percent grain 44.0 34.4 29.3

DM yield, ton/acre 6.6 7.6 8.8

sorghum. DeKalb FS 5 is a middle-season,moderate grain-content hybrid; and DeKalbFS 25E is a late-season, low grain-contenthybrid. On day 1 of each experimentalperiod, the steers were allocated randomly toone of the six rations. The rations wereformulated to be isonitr ogenous and were fedad libitum twice daily (8 am and 3 pm). Each16-day experimental period consisted of 8days for adaptation, 4 days for total fecalcollection, and 4 days for rumen collection.

On day 12 of each experimental period,samples of ruminal digesta were collectedbefore the first feeding (0 hour) and at 2, 4,6, and 10 hours after the first feeding. Thesamples consisted of subsamples from thedorsal blind sac, mid-dorsal region, mid-ventral region, and the reticulum. On day 2of the ruminal collection period, 1.0 kg ofytterbium-labeled silage and 250 ml ofsodium cobalt EDTA were pulse-dosedruminally before the first feeding (0 hour).Ruminal fluid and particulate samples werecollected at 4, 8, 12, and 24 hours afterdosing. Liquid and particulate dilution rateswere determined by regressing the naturallogarithm of the Yb and Co concentrationsagainst time after dosing.

Data were analyzed using the SAS GLMprocedure. Fermentation profile data wereanalyzed as a split-plot in time 6 × 6 Latinsquare design using a t-test for meanseparations. Terms in the fixed effects modelincluded the main effects of period, steer,time, sorghum hybrid, and grainsupplementation and their interactions.Sorghum hybrid, grain supplementation, andsorghum hybrid by grain supplementation(whole-plot) effects were tested forsignificance by using the whole-plot residualsums of squares (sorghum hybrid by grainsupplementation by period by steer). Time,time by sorghum hybrid, time by grainsupplementation, and time by sorghum hybridby grain supplementation (subplot) effectswere tested for significance by the subplotresidual sums of squares.

Digestibility, intake, and pass age rate datawere analyzed as a 6 × 6 Latin square using

a t-test for mean separations. Terms in thefixed effects model included period, steer,sorghum hybrid, and grain supplementationand their interactions.


The nutrient composition and agronomicdata for the three silages are presented inTable 1.

Interactions between grain supplementa-tion and the three sorghum silages were notstatistically significant for any of the digestioncriteria measured (Table 2). However,adding grain to the DeKalb 42Y and DeKalbFS-5 silage rations tended to reduce starchdigestibility (14.1 and 3.9%, respectively).Starch digestibility of the DeKalb FS-25Esilage rations was not affected by grainsupplementation.

Intakes of DM and digestible DM werehighest (P<.001) for steers fed the DeKalb42Y silage rations (Table 2). Dry matter andOM digestibilities were highest (P<.05) forthe DeKalb 42Y and DeKalb FS-5 silagerations. Acid detergent fiber digestibility wasgreatest (P<.05) for DeKalb 42Y silage


79

rations, but NDF and starch d igestibilities andliquid and particulate passage rates were notaffected (P>.05) by sorghum hybrid.Ammonia, acetate, propionate, butyrate, andtotal VFA concentrations were highest(P<.05), whereas acetate/propion a te ratio andpH were lowest (P<.05) for steers fedDeKalb 42Y silage rations (Tab le 3). DeKalbFS-5 and DeKalb FS-25E silage rationsproduced statistically similar ruminalfermentation characteristics.

Grain supplementation increased(P<.001) intakes of DM and digestible DMby 25 and 34%, respect ively, when comparedto control rations (Table 2). Dry matter andOM digestibilities were increased (P<.05) by5.1 and 5.2%, respec tively, by grain addition.Starch digestibility tended to decrease(P=.06) with grain supplementation. Aciddetergent fiber digestibility (P=.50), NDFdigestibility (P=.21), liquid passage rate(P=.30), and particulate passage rate (P=.49)were not affected by grain suppl ementation ofthe sorghum silage-based rations.

Table 2. Effect of Hybrid and Grain Supplementation of Sorghum Silage-Based Rations on DMIntake, Intake of Digestible DM, and Nutrient Digestibilities and Passage Rates inGrowing Steers1

Sorghum Silage and Grain Addition

DeKalb42Y

DeKalbFS 5

DeKalbFS 25E Probability2

Item 0 25% 0 25% 0 25% SE H G H×G

DM intake, lb/day 16.5 19.0 13.0 16.5 10.6 14.1 .62 .001 .001 NS

Intake of DDM, lb/day 10.1 12.1 7.7 10.1 5.5 8.6 .48 .001 .001 NS

Digestibility, %

DM 62.1 63.8 59.5 61.3 52.5 59.8 1.70 .01 .05 NS

OM 63.4 64.5 61.0 62.6 55.5 62.3 1.80 .05 .05 NS

NDF 52.7 56.9 52.9 51.7 46.2 51.5 2.60 NS NS NS

ADF 53.2 53.6 44.4 39.9 41.7 39.8 3.50 .01 NS NS

Starch 85.4 73.4 85.6 81.7 81.1 81.7 3.20 NS NS NS

Particulate passage rate, %/h 5.1 5.2 5.5 4.0 4.0 3.0 .94 NS NS NS

Liquid passage rate, %/h 7.8 8.4 9.3 9.9 9.5 7.1 .69 NS NS NS

Values are least square means, and SE is the pooled standard error of the mean.1

H = hybrid, G = grain, H×G = hybrid x grain interaction, NS = not different.2


80

Table 3. Effects of Hybrid and Grain Supplementation of Sorghum Silage-Based Rations onRuminal Fermentation Characteristics in Growing Steers 1

Sorghum Silage and Grain Addition

DeKalb42Y

DeKalbFS 5

DeKalbFS 25E Probability2

Item 0 25% 0 25% 0 25% SE H G H×G

pH 6.6 6.5 6.8 6.7 6.8 6.8 .02 .01 .01 NS

Ammonia, mM 5.7 5.5 4.5 4.2 4.7 3.8 .31 .01 NS NS

VFA, mol/100 mol

acetate 63.0 60.6 54.4 58.0 58.2 58.4 1.40 .01 NS NS

propionate 18.6 19.8 15.9 16.8 16.2 16.0 .57 .01 NS NS

butyrate 9.7 8.0 7.0 7.8 7.1 7.4 .29 .01 NS .05

Total VFA, mM 97.5 94.6 81.8 88.1 86.8 86.8 2.30 .01 NS NS

Acetate/ propionate 3.5 3.2 3.5 3.6 3.6 3.7 .07 .01 NS NS

Values are least square means, and SE is the pooled standard error of the mean.1

H = hybrid, G = grain, H×G = hybrid × grain interaction, NS = not different.2


Graduate Student. Department of Animal, Dairy, and Veterinary Sciences, Utah State1

University, Logan, UT. USDA, ARS, FRRL, Logan, UT.2

Nutrition/Forage Specialist. Pioneer Hi-Bred International Inc., Boise, ID.3

81


LOCATION EFFECTS ON FORAGE PRODUCTION AND QUALITYAMONG SELECTED PIONEER CORN HYBRIDS

D. G. Tieman n , K. K. Bolsen,1

D. H. Clark , and W. Kezar 2 3

Summary

Six Pioneer corn hybrids were grown inKansas and four of the six hybrids withinthree locations in Utah. The Utah hybridswere harvested between the one-quarter andone-half milk line stages of kernel maturity,whereas the Kansas hybrids wer e harvested atapproximately 90% of kernel maturity.Location had a significant effect on theagronomic characteristics and chemicalcomposition of the hybrids. Whole-plant drymatter (DM) and digestible DM yield, grainyield, and percent grain were higher in theKansas-grown corn. The greater yield andproportion of grain were results of the excel-lent growth conditions in 1992 and their ad-vanced stage of kernel maturity at harvest.Experimental hybrid X0811 yielded thehighest whole-plant DM, grain, stover, anddigestible DM among the Kansas corns.Hybrid X0811 also had the highest whole-plant and stover in vitro DM digestibility(IVDMD), the highest whole-plant andstover crude protein (CP), and the lowestwhole-plant and stover neutral detergent fiber(NDF) and acid detergent fiber (ADF)contents among the Kansas corns. HybridX0811 had the highest stover and digestibleDM yields, whole-plant C P and IVDMD, andstover IVDMD and the lowest stover NDFand ADF contents among the Utah hybrids.The high digestible DM yields of hybridX0811 emphasize the contribution of thestover fraction, in addition to the proportion

of grain, to the quality of the whole-plantforage.

(Key Words: Corn, Hybrid, Kansas, Utah.)

Introduction

The goal of an efficient corn silageproduction system oriented towards produc-ing beef is to consistently maximize beef yieldper acre. Therefore, corn silage producersstrive for excellent silage managementpractices and search for corn hybrids withsuperior performance (i.e. high digestibleenergy yields per acre). To betteraccommodate corn silage producers, seedcompanies and universities are providinginformation not only on forage and grainyields, but also on plant part proportions(percent grain, stover, and cob) and digest-ibilities (whole-plant and stover).

However, limited information exists onthe relative quality of superior forage cornhybrids grown with various fertility andirrigation practices and environmentalconditions.

As a result of the corn hybrid evaluationtrial in 1990 (KAES Report o f Progress 592),a cooperative research project was organizedbetween Utah State and Kansas StateUniversities and Pioneer Hybrid Inc. todetermine not only the forage yield andquality of several corn hybrids, but also the


82

influence of production conditions on theforage yield and quality of the respectivehybrids.


Six mid-maturing, Pioneer, corn hybridswere grown in 1992. The corn hybridsselected by Pioneer for evaluation consistedof experimental (X0811, X181 4, XC951) andcurrently marketed (3215, 3299, 3377)hybrids. The hybrids X0811, X1814, 3215,and 3377 were grown at three locations inUtah, and the hybrids X0811, X1814,XC951, 3215, 3299, and 337 7 were grown inKansas at a single location. All hybrids weregrown under irrigated conditions. The cornhybrids were organized into randomizedcomplete blocks with three replications ateach location.

The locations in northern Utah wereHooper, Ellwood, and Bear River City. Thehybrid plots in Utah were planted in 30 in.rows at plant populations of approximately28,000 plants/acre.

The hybrids at Hooper were planted onApril 25 in a Syracuse loamy fine sand soilthat had been previously planted to alfalfaand heavily manured. Seventy-five lb peracre of N as ammonium nitrate was appliedside-dress at furrow-making to meet soilrequirements (N, P, and K). The hybridswere harvested on August 31.

The hybrids at Ellwood were planted onApril 14 in a Fielding silt loa m, warm soil thathad been heavily manured. Eighty lb N and60 lb P per acre were applied prior toplanting to meet soil requirements (N, P, K).The hybrids were harvested on August 31.

The hybrids at Bear River City wereplanted on April 20 in a Fielding silt loam,warm soil that was fertilized with 175 and 75lb per acre of N and P, respectively, to meetsoil requirements (N, P, K). The hybridswere harvested on September 1.

The corn hybrid plots in Kansas werelocated at Manhattan. The plots were

planted in 30 in. rows at populations ofapproximately 22,000 plants per acre. Thehybrids were planted on May 20 in a Readingsilt loam soil that was fertilized with 100 lbper acre of liquid N that fulfilled soilrequirements (N, P, K). The hybrids wereharvested during the second week ofSeptember.

All Utah hybrids were harvested when thekernels at the center of the ear were betweenthe one-quarter and one-half milk line stagesof maturity. In each plot, 10 plants werehand-harvested and weighed, and plant partswere separated to determine yield (wholeplant, stover, ear, and cob) and plant partproportions (percent grain, stover, and cob).The whole plant and stover were choppedwith a Kemp chipper-shredder andsubsequently sampled for chemical analysis.The remaining ears from the plantsdesignated as stover were frozen and laterhand-shelled to determine grain and cobfractions.

In Kansas, the hybrids were harvestedwhen the milk line in the kernels at the centerof the ear had progressed throughapproximately 90% of kernel (just prior toblack layer formation). Two inner rows,within a 25-foot-long plot of si x rows, wereharvested for whole-plant yield, and theremaining two inner rows were used todetermine plant part yields and proportions.The whole-plant and stover were harvestedand weighed with a modified one-row foragechopper. Samples of the whole-plant andstover material were taken after theharvesting process for chem ical analysis. Thetwo outside rows of each plot weredesignated as border rows and ignored.

The husk remaining from ear separationwas included in the stover fraction at alllocations. The samples of all plant parts thenwere dried in a forced-air drying oven.Chemical analysis was performed on allsamples using standard techniques.

The donor animal for the IVDMDanalysis was a 4-year-old 1200 lb, lactating,crossbred, beef cow fitted with a rumen


83

cannula. The ration was 90% corn silage and10% supplement on a DM basis, wasformulated to 10.5% protein, and met NRCrequirements for vitamins and minerals. Theanimal was fed ad libitum twice daily andconsumed from 27 to 35 lb DM of corn silageper day. The fluid for in vitro analyses wascollected immediately prior to the a.m.feeding.


The agronomic characteristics are pre-sented in Table 1. The chemical compositionof the whole plant and stover are provided inTables 2 and 3, respectively. Because thelocation by corn hybrid interaction wassignificant, the corn hybrids are presentedwithin their respective locations. However,to more efficiently present the Kansas resultsfor this publication, the results of the hybridsat each location in Utah have been combinedas corn hybrid averages across Utah.

Whole-plant DM yield in Utah rangedfrom 9.0 to 10.58 tons per acre in cornhybrids 3215 and 3377, respectively, with anaverage of 10.01 tons. Whole-plant DM yieldin Kansas ranged from 9.78 to 11.08 tons peracre in corn hybrids 3299 and X0811,respectively, with an average of 10.43 tons.The Utah-grown corn was able to maintainwhole-plant DM yields equivalent to those ofthe Kansas corn even though the whole-plantDM content of the Utah corn was lower(27.46 vs 34.13%). This is a result of thehigher plant populations of the Utah-growncorn.

The Kansas corn had higher whole-plantDM (27.46 vs 34.13) and CP (6.04 vs 8.01)contents than the Utah corn. The higherwhole-plant DM content was a result of theadvanced maturity of the Kansas corn. Thehigher DM content of the grain (notpresented) elevated the whole-plant DMwhen compared to the stover DM alone. Thedifferences in CP conten t were predominatelyfunctions of soil fertility and factors affectingsoil nutrient exchange.

Grain yields in Utah ranged fr om 109.7 to158.2 bu per acre in corn hybrids 3215 and3377, respectively, with an average of 132.7bu. Grain yields in Kansas were higher andranged from 191.2 to 215.8 bu per acre incorn hybrids 3215 and X0811, respectively,with an average of 205.6 bu.

Stover DM yield was not significantlydifferent across the corn hybrids in Utah andaveraged 5.92 tons per acre . In Kansas, thestover DM yields were lower and rangedfrom 3.89 to 5.06 tons per acre in cornhybrids 3299 and X0811, respectively, withan average of 4.64 tons.

The Kansas-grown corn contained higherproportions of grain and lower proportions ofstover and cob than did the Utah corn. Thehigher grain yield and proportion of grain wasprimarily due to the excellent growthconditions in 1992 and the more advancedstage of maturity, resulting in a greaterproportion of the who le-plant DM residing inthe grain.

Digestible DM yield was hig her in Kansasthan in Utah, 7.32 vs 6.93 tons per acre,which was primarily due to the higher whole-plant DM content and grain proportion in theKansas-grown corn. The higher grainproportion in the Kansas corn reduced theADF and NDF content of the who le-plant drymatter. Hybrid X0811 had the highestdigestible DM yield across both Utah andKansas. The high digestible DM yield ofhybrid X0811 was a result of its high whole-plant IVDMD and low whole-plant NDF andADF. The stover fraction of hybrid X0811had the lowest NDF and ADF contents andthe highest IVDMD in both Kans as and Utah.The high quality of whole-plant X0811emphasizes the contribution of the stoverfraction to the quality of the whole-plant drymatter. Therefore, experimental corn hybridX0811 has the potential to be labeled as asuperior forage hybrid because it consistentlyyields high proportions of grain and producesa high quality stover.


84

Table 1. Whole-Plant, Grain, Stover, and Digestible DM Yields, and Plant Part Proportionsof the Corn Hybrids Grown in Utah and Kansas

LocationandHybrid

Whole-PlantDM Yield,tons/acre

Grain Yield,

bu/acrea

StoverDM Yield,tons/acre

DigestibleDM Yield,tons/acre

Plant Part (% DM basis)

Grain Stover Cob

Utahb

X0811

X1814

3215

3377

10.01

10.39

10.13

9.00

10.58

132.7

141.0

136.8

109.7

158.2

5.92

5.99

5.92

5.58

5.76

6.93

7.51

6.90

6.05

7.31

31.7

33.1

33.4

28.4

35.9

60.8

59.9

59.7

63.9

55.8

7.5

7.0

6.9

7.7

8.3

Kansasb

X0811

X1814

3215

3377

3299

XC951

LSD (P<.05)c

10.43

11.08

10.71

10.21

9.94

9.78

10.83 1.21

205.6

215.8

209.4

191.2

197.2

210.7

209.4

20.46

4.64

5.06

4.73

4.89

4.35

3.89

4.89

0.62

7.32

8.10

7.50

7.04

6.92

7.03

7.32

0.95

49.2

48.8

49.7

46.0

48.9

54.0

47.8

1.93

45.6

46.8

45.4

49.1

44.9

40.9

46.8

2.20

5.2

4.4

4.9

4.9

6.2

5.1

5.4

0.49

Adjusted to 14.5% moisture.a

Utah and Kansas means, respectively.b

The LSD (least significant difference) is valid only among corn hybrids within Kansas.c


85

Table 2. Chemical Composition and I n Vitro Digestibility of the Whole-Plant Forage of CornHybrids Grown in Kansas and Utah

Locationand Hybrid

Dry Matter,% CP NDF ADF IVDMD

------------------ % of the forage DM ------------------

Utaha

X0811 X1814 3215 3377

27.4626.7327.7027.6029.85

6.046.505.965.946.11

48.6347.7448.0250.5745.91

28.7527.4129.3030.1326.14

69.3072.3968.3367.3769.19

Kansasa

X0811 X1814 3215 3377 3299 XC951

LSD (P<.05)b

34.1334.6335.9732.1131.2537.8732.91

6.26

8.018.608.328.367.707.327.75

0.46

41.6439.8139.8444.6741.6940.7943.04

3.98

24.8423.0923.4727.6025.2723.8125.77

2.62

70.1673.1369.9668.9369.5871.7667.55

2.34

Utah and Kansas means, respectively.a

The LSD (least significant difference) is valid only among corn hybrids within Kansas.b

Table 3. Chemical Composition and In Vitro Digestibility of the Stover Fraction of CornHybrids Grown in Utah and Kansas

Locationand Hybrid

Dry Matter,% CP NDF ADF IVDMD

------------------- % of the forage DM -------------------

Utaha

X0811 X1814 3215 3377

22.3021.2322.4823.2023.29

5.385.535.305.505.68

61.8760.9062.4062.3660.75

39.7538.2541.8639.7538.54

63.7167.1061.4562.1464.17

Kansasa

X0811 X1814 3215 3377 3299 XC951

LSD (P<.05)b

24.0123.6123.5022.8421.1526.9726.01

2.18

6.386.606.176.257.186.405.72

0.88

62.0457.5263.3663.7662.4462.6962.45

2.54

41.1438.3842.2942.4240.7941.1241.87

2.62

60.1165.4757.6358.8261.0562.2655.44

4.15

Utah and Kansas means, respectively.a

The LSD (least significant difference) is valid only among corn hybrids within location.b


Appreciation is expressed to Gary Ritter and Wayne Adolph and the student workers at1

the Cow-calf Unit for their invaluable assistance in conducting this trial. Present address: Chadron State College, 1000 Main Street, Chadron, NE 69337.2

Fort Hays Branch Experiment Station, Hays, KS.3

86


EFFECT OF GRAIN TYPE IN SUPPLEMENTS ANDSUPPLEMENTATION FREQUENCY ON THE PERFORMANCE

OF BEEF COWS GRAZING WINTER RANGE 1

R. C. Cochran, J. L. Beat y , and E. S. Vanzant 2 3

Summary

One hundred twenty, pregnant, Angus ×Hereford cows (1111 lb) grazing dormantbluestem range were used to evaluatewhether the effect of altered frequency ofsupplementation on cow performance de-pended on the grain type in the supplement.Two supplementation frequencies (daily andthree times weekly) and two grain types inthe supplements (sorghum grain or corn)were evaluated. Both supplements contained21% CP and were fed to provide 32.6 lbDM/week. Interactions were not significant.Winter weight loss through calving wasgreater (P#.02) for the cows supplementedthree times weekly, although the magnitudeof the effect was not large. Use of differentgrain types in the supplements did notsignificantly affect most performancevariables.

(Key Words: Beef Cattle, Frequency,Supplements.)

Introduction

Feeding supplements with relatively highcrude protein (CP) concentrations hasimproved the performance of beef cowsgrazing winter range. However, feedingsupplements daily can require considerablelabor and equipment under range conditions.If one could reduce supplementationfrequency without negatively affecting

livestock performance, reduced labor andequipment demands might result.

Many studies conclude that high-proteinsupplements can be fed infrequently withoutsignificantly harming cow performance.However, few studies have evaluated theimpact of altering supplementation frequencywhen supplements contain low to moderateconcentrations of protein.

Some research suggests that alt ernate-daysupplementation with low- to moderate-protein supplements (i.e., grain-basedsupplements with 10 to 25% CP) degradesperformance compared with daily supple-mentation.

In contrast, a recent experimen t at KansasState University suggests that the effect ofaltering the frequency of supplementation issimilar, regardless of the supplement's proteinconcentration (range from 10% to 40% CP).One explanation for that contradiction maybe the grain type used in the supplements.Kansas State's experiment used supplementsbased on sorghum grain, which is a slowlyfermented grain. Other research usedsupplements based on corn, which is rapidlyfermented. Therefore, our objective was tomonitor changes in gain and condition ofcows grazing winter range and receivingsupplements based on corn or sorghum graineither daily or three times weekly.


87


One hundred and twenty pre gnant, Angus× Hereford, beef cows (avg. initial BW =1111 lb; avg. initial condition score = 5.4)were used in a 2 × 2 factorial designcomparing supplementation frequency (daily= 7X, or three times weekly = 3X) and graintype in the supplement (corn or sorghumgrain). Both supplements were formulated tocontain 20% CP (dry basis). Actual CP was21% for both supplements. Each supplementcontained approximately 74% grain, 23%SBM, and 3% molasses.

All treatment groups were fed 32.6 lb drymatter per week. The 7X group received14.65 lb DM/feeding; the 3X group, 10.86 lb.Body weight and condition were measuredon days 0, 28, 56, and 84 and at calving (avg= day 111). Cows grazed four bluestem-range pastures (approximately 305 acreseach) throughout the trial.

Each feeding-frequency treatment wasassigned to two pastures, with c ows receivingcorn- and sorghum grain-based supplementsequally represented within each pasture. The7X cows were gathered daily, whereas the3X cows were gathered only on Mondays,Wednesdays, and Fridays. Followinggathering, cows were sorted and group-fedtheir supplement in a bunk. The feeding areawas located in the center of the four pastures.To monitor effects on cow behavior, an areawithin .25 miles of the central feeding areawithin each pasture was marked with paintedmetal posts. Cattle presence or absencewithin this area before gathering for feedingwas recorded daily. Supplements were fedfrom November 30, 1992 until calving.


The response to frequency of supple-mentation did not depend on the grain

type in the supplements. Calving date wassimilar (P>.10) among treatments, averagingMarch 16, 1993 (day 111). Calf birthweights were also similar (P$.17) amongtreatments (avg. birth wt. = 83 lb).

Although cumulative and period changesin body weight (Table 1) were n o t significant-ly altered by grain type in the supplement, atrend (P = .07) was observed for those fedthe corn-based supplement to lose slightlyless condition through calving.

Although cows on the 3X treatment lostmore (P = .02) weight by calving time thanthe 7X group, the difference (approximately24 lb) was not great from a biologicalstandpoint. That was corroborated by thelack of effect (P = .47) on cumulative bodycondition change during the same timeperiod. Cows in the 3X group were morelikely (P<.01; 18.1% vs 37.5% for the 7Xand 3X groups, respectively) to be foundclose to the feeding area before the morningsupplementation period.

Although cow performance and behaviorwas favored by daily supplementation, themagnitude of the changes were so small thatthree-times-weekly supplementation appearsto be a viable way to reduce labor andequipment costs. The results of the currentexperiment were similar to those fromprevious research at Kansas State University,adding further support to our previousconclusion that response to alteredsupplementation frequency does not dependon the protein concentration in the supple-ment.

Although infrequent supplementation ap-pears to be feasible with low- to moderate-protein supplements, an adequate balancemust exist between supplemental protein andenergy in order to ensure acceptable cowperformance and efficient use of low-qualityforage.


88

Table 1. Influence of Frequency of Supplementation and Grain Type in Supplement onCumulative and Period Weight and Body Condition Changes in Beef Cows GrazingDormant Bluestem Range

Grain Type Frequencya

SorghumItem Corn Grain SEM P value 7X 3X SEM P value

Initial wt, lb 1111.7 1111.2 11.4 .97 1112.6 1110.4 .97 .23

Cumulativewt. change, lbd 1-28 -39.2 -44.3 3.31 .39 -44.7 -38.8 5.88 .55d 1-56 -35.5 -42.1 2.47 .20 -26.7 -50.9 5.91 .10d 1-84 -43.6 -56.2 7.40 .36 -30.2 -69.6 2.31 <.01d 1-111 -180.3 -189.8 4.74 .30 -174.6 -195.5 4.03 .02

Period wtchange, lbd 1-28 -39.2 -44.3 3.31 .39 -44.7 -38.8 5.88 .55d 28-56 3.7 2.2 2.36 .71 18.1 -12.1 4.01 .03d 56-84 -8.4 -12.8 4.96 .58 -3.5 -17.6 6.17 .25d 84-111 -138.6 -136.0 4.73 .73 -147.2 -123.0 3.70 .06

Initial bodycondition 5.4 5.4 .01 .81 5.4 5.4 .003 .10b

Cumulative bodycondition changed 1-28 -.10 -.21 .041 .20 -.11 -.21 .008 .01d 1-56 -.36 -.50 .037 .12 -.40 -.46 .011 .08d 1-84 -.75 -.91 .059 .18 -.85 -.81 .040 .49d 1-111 -1.11 -1.26 .031 .07 -1.16 -1.21 .044 .47

Period bodycondition changed 1-28 -.10 -.21 .041 .20 -.11 -.21 .008 .01d 28-56 -.26 -.29 .031 .58 -.29 -.25 .019 .22d 56-84 -.39 -.43 .024 .41 -.46 -.36 .048 .26d 84-111 -.36 -.37 .025 .94 -.31 -.42 .020 .06

Frequency of supplementation: 7X=daily; 3X=three times weekly.a

Body condition scored on a 1-9 scale, 1 = emaciated and 9 = extremely obese.b


The authors express their appreciation to Gary Ritter, Wayne Adolph, Gary Breault, and1

Mike Sheffel for their expert assistance in conducting this experiment. Fort Hays Branch Experiment Station, Hays, KS.2


89


DORMANT, TALLGRASS-PRAIRIE FORAGE:INFLUENCE OF RUMINAL DEGRADABLE

PROTEIN ON INTAKE BY BEEF COWSAND FERMENTATION CHARACTERISTICS 1

H. H. Köster, R. C. Cochran, E. C. Titgemeyer,E. S. Vanzan t , and G. St. Jea n 2 3

Summary

Five ruminally and duodenally fistulatedAngus × Hereford cows were fed dormanttallgrass-prairie forage ad libitum to monitorintake and fermentation responses associatedwith providing increasing amounts ofsupplemental ruminal degradable protein(RDP). The RDP was provided from sodiumcaseinate and infused intraruminallyimmediately before feeding forage. Levels ofRDP were 0, 180, 360, 540, and 720 g/d.Maximal intake of dormant, tallgrass-prairieforage occurred with provision of 540 gRDP/d. Ruminal dry matter fill declined withincreasing level of RDP infusion. Increasingsupplmentation of RDP generally improvedruminal fermentation characteristics.

(Key Words: Beef Cows, Ruminal De-gradable Protein, Intake, Forage.)

Introduction

Ruminants depend on the micr oorganismsthat inhabit the rumen for effective use offiber in forages. However, when low-qualityforages are fed, protein and other importantmicrobial nutrients may be deficient, limitingthe ability of fiber- digesting microorganismsto grow and to ferment fo rage fiber. In orderto overcome such deficiencies, supplementalruminal degradable protein (RDP) frequentlyis required. Furthermore, intake of low-quality forage is increased in response to theprovision of RDP. Because protein supple-

mentation can be costly, it is important toknow the amount of RDP required to opti-mize forage intake and digestion. Therefore,our objective was to determine the influenceof different RDP levels on the intake andfermentation characteristics of a low-quality,tallgrass-prairie forage by beef cows.


Five ruminally and duodenally fistulatedAngus × Hereford cows (1296 lb) werepenned individually and fed dormanttallgrass-prairie forage (1.9% crude protein[CP]; 70% neutral detergent fiber) ad libitumfor the duration of the experiment. RDP wasprovided in the form of sodium caseinate(casein; 90% CP) which was solubilized inwater (7 liters/d), divided into two equalportions, and infused intraruminally at 6:30a.m. and 6:30 p.m. immediately beforefeeding forage. Levels of RDP were 0, 180,360, 540, and 720 g/d. The amounts of RDPprovided by these infusion levels would beapproximated by 0, 1.1, 2.2, 3.3, or 4.4 lbsoybean meal/d (dry matter [DM] basis),respectively, if the SBM contained approxi-mately 50% CP on a dry basis (assumesapproximately 75% of CP is ruminallydegradable). During each experimentalperiod, the cows were adapted to the dietsfor 14 days. Voluntary intake then was mea-sured, and digesta samplings were made overthe next 4 days. Subsequently, each cow'srumen was emptied manually to determineruminal DM and liquid fill. Ruminal


90

evacuations were performed just prior to (0h) and 4 h after feeding hay and infusingcasein. Ruminal fluid samples were obtainedat several times after feeding to determinepH, ammonia N (NH N), and volatile fatty3acid (VFA) concentrations.


Forage DM intake increased in a qua-dratic (P<.01) fashion in response toincreasing RDP infusion, with the peakobserved at the 540 g infusion level (Table1). This quantity equates to providing .42 gRDP/lb of BW. Increased forage intake inresponse to RDP concurs with the results ofnumerous other research t rials. The directionand magnitude of the effect on forage intakefurther verifies the need to provide RDP toensure optimal utilization of low-qualityforage.

Table 1. Influence of Amount of Ruminal Degradable Protein (RDP) on Intake, Ruminal Fill, andRuminal Fermentation in Beef Cows Consuming Dormant Tallgrass-Prairie Forage

RDP Level (g/day) Effecta

Item 0 180 360 540 720 L Q C SEM

FDMI , g/kg BW 32.2 52.7 63.1 70.2 67.7 <.01 <.01 .97 3.08b .75

Ruminal DM fill, g/kg BW 15.3 14.7 15.9 12.3 12.4 .09 .95 .22 .40.75

Liquid fill, g/kg BW 102 96 104 109 105 .03 .99 <.01 2.50.75

pH 6.92 6.62 6.63 6.58 6.52 <.01 <.01 .02 .02NH N, mM 0.24 1.36 3.47 5.17 6.87 <.01 .80 .69 .733

VFA, mM 43.3 65.9 71.4 74.5 76.4 <.01 <.01 .04 2.18Acetate, moles/100 moles 78.0 75.4 74.8 73.6 72.4 <.01 .15 .14 .39Propionate, moles/100 moles 15.2 16.1 16.3 16.5 15.7 .01 <.01 .50 .15Butyrate, moles/100 moles 6.11 6.18 5.98 6.19 6.33 .18 .13 .52 .09Isobutyrate, moles/100 moles .43 .78 .94 1.11 1.70 <.01 .08 .02 .08Isovalerate, moles/100 moles .17 .84 1.14 1.40 2.21 <.01 .66 .05 .14Valerate, moles/100 moles 0 .68 .91 1.17 1.60 <.01 .31 .12 .12Acetate:propionate 5.14 4.70 4.61 4.48 4.66 <.01 <.01 .90 .08

Probability of a greater F value. L=linear change with increasing RDP, Q=quadratic change with increasing RDP,a

C=cubic change with increasing RDP.FDMI=forage dry matter intake.b

DM=dry matter.c


91

The influence of treatment on ruminalDM and liquid fill did not depend (P>.10) onthe time of ruminal evacuation. At bothevacuation times, liquid fill decreasedsomewhat with the 180 g infusion level,increased to a peak at the 540 g infusionlevel, and then slightly declined (cubic,P<.01). In contrast, ruminal DM fill tended(P=.09) to decrease linearly with increasinginfusion level. The response for DM fill isopposite to that in previous trials at KansasState University. The different responsemight be because RDP was infused alone,compared with actually feeding a supplementthat contains RDP as well as other nutrients.In the present experiment, the increased for-age DM intake with increasing RDP infusionappears related to changes in forage digest-ibility and (or) passage.

Variability was observed in theresponse over time for the different fer-mentation variables measured. Ruminal pHdecreased rapidly with the initial RDP

level, stabilized with the intermediate infusionlevels, and then decreased slightly with thehighest infusion level (cubic, P=.02). TotalVFA concentration increa sed rapidly with theinfusion of 180 g RDP/d and continued toincrease slightly with increasing caseininfusion (cubic, P=.04). Acetate proportiondeclined linearly (P<.01) with increasinginfusion level, whereas propionate andacetate:propionate ratio responded in aquadratic (P<.01) manner. The peak inpropionate and the low point in the ace-tate:propionate ratio corresponded withmaximal forage DM intake. Molar propor-tions of isobutyrate and isovalerate increasedwith initial infusion level, continued toincrease slightly with the intermediateinfusion levels, and then exhibited a largerproportional increase at the highest level ofinfusion (cubic, P<.05). Valerate tended(P=.12) to follow the same trend. In general,increasing availability of RDP improvedruminal fermentation characteristics,reflecting improvement in nutrient supply tomicroorganisms.


The authors express their appreciation to Gary Ritter, Wayne Adolph, Gary Breault, and1

Mike Scheffel for their invaluable assistance in conducting this experiment. Fort Hays Branch Experiment Station, Hays, KS.2

Department of Agronomy.3

92


EVALUATION OF THE POTENTIAL OF SUPPLEMENTSTO SUBSTITUTE FOR RANGE FORAGE 1

S. D. Stafford, R. C. Cochran,E. S. Vanzan t , and J. O. Fritz 2 3

Summary

Thirteen, ruminally fistulated, Angus ×Hereford, yearling steers were used toevaluate the effect of feeding different typesand amounts of supplements on t he likelihoodof observing a substitution of supplement forrange forage. Steers had ad libitum access tolow-quality range forage and were fed asupplement comprised of sorgh um grain (SG)and soybean meal (SBM) that contained 18%CP (SG/SBM 18%), a SG/SBM supplementthat contained 36% CP (SG/SBM 36%),long-stem alfalfa hay (18% CP), or alfalfa-pellets (18% CP) in amounts that provided.05, .10, and .15 % BW o f CP/day. In gener-al, supplementation increase d the intake anddigestibility of low-quality range forage. Nosubstitution effect was observed for theSG/SBM 36% supplement or the alfalfapellets. However, the SG/SBM 18% sup-plement did substitute for forage at the highlevel of supplementation. A similar trendappeared to exist for the long-stem alfalfahay.

(Key Words: Supplementation, Alfalfa,Range Forage, Pellets.)

Introduction

Providing supplements with moderate tohigh protein content has been shown to bebeneficial for beef cows maintained ondormant, native range. Increased intake of

range forage by supplemented cattle com-pared with nonsupplemented cattle is a majorfactor contributing to the positive effect ofsuch supplements. However, the likelihoodthat a supplement substitutes for range forageincreases as the amount of supplement fedincreases. Furthermore, the amount requiredto elicit substitution effects may vary forsupplements with different phys ical propertiesand (or) with different effects on digestivephysiology. Therefore, our objective was toobserve the influence of varied types andamounts of supplements on the likelihoodthat supplement will substitute for forage. Inaddition, associated effects on digestion andfill were monitored.


Thirteen ruminally fistulated Angus ×Hereford steers (avg initial wt = 574 lb) wereused in an incomplete Latin square with 13treatments and four periods. Steers weremaintained in individual tie stalls and feddormant, bluestem-range forage (CP ~2%)once daily at 130% of their previous 5-dayaverage intake. Treatments were arranged asa 3 × 4 factorial plus a negative controltreatment. Steers on the negative controltreatment were unsupplemented. The firstfactor, amount of supplement, was designedso that steers received a daily amount of eachsupplement providing .05, .10, or .15 % bodyweight (BW) as crude protein (CP). Thesecond factor, supplement type, was set such


93

that each of four supplements was fed withineach supplementation level . The supplementswere: 1) a sorghum grain (SG) and soybeanmeal (SBM) mixture that contained 18% CP(SG/SBM 18%); 2) a SG/SBM mixture thatcontained 36% CP (SG/SBM 36%); 3) long-stem alfalfa hay (LSAH); 4) alfalfa pellets(AP). The LSAH and AP were from thesame source. The pellets were made bygrinding through a 3/16" screen and pressinginto a 1/4" pellet. The CP concentrations ofthe LSAH and AP were approximately thesame as that of the SG/SBM 18%. Becausethe supplement amount was se t relative to theamount of protein provided per unit of BWand because the SG/SBM 36% supplementcontained twice the CP as the other supple-ments, the amount of supplement dry matter(DM) fed for the SG/SBM 36% supplementwas half that for the other supplements. Ifexpressed as the amount of DM fed per unitof BW, the SG/SBM 18%, LSAH, and APsupplements received approximately .28, .56,and .83 % BW daily, corresponding to 2.8,5.6, and 8.3 lbs of supplemen t DM for a 1000lb cow. Steers were adapted to eachtreatment for 16 days. Forage intake wasmeasured during the 7-day periodimmediately following adaptation. Totalfecal collections began 2 days after thebeginning of intake measurements and ended2 days after the last intake measurement. Atthe end of total fecal collection, total ruminalevacuations were performed (before feeding,0 h, and 4 h after feeding) on each animal todetermine ruminal fill.


Range forage intake increased linearly(P<.01) with increasing amounts of theSG/SBM 36% and AP (Table 1). In contrast,range forage intake for steers fed SG/SBM18% increased up to the .10%supplementation level and then declined whensteers were fed the .15% level (P = .03).This suggests that for every unit of additionalsupplement fed above the intermediate level,there was a decrease of .54 units of rangeforage. That is, for a 1000 lb cow, about .54lb decrease in range forage intake wouldoccur for each additional 1.0 lb of SG/SBM

18% DM fed above about 5.6 lbs. Althoughnot statistically significan t (P = .37), the trendfor the LSAH group was s imilar. For LSAH,a decrease of .48 units of range forageoccurred for each additional unit of LSAHfed above the intermediate level of supple-mentation. Similar substitution ratios havebeen observed for LSAH supplements inother research at Kansas State University.Because substitution was only partial in thosetreatments where it occurre d, total dry matterintake (DMI) increased for all treatments inresponse to increasing supplementation.

Dry matter digestibility (DMD) increasedlinearly (P<.01) with increasing levels allsupplements. Provision o f nitrogen and othermicrobial nutrient requirements, as well ashigher digestibility for the supplement thanthe hay, were probably responsible for thatincrease. No difference was s een in DMD forthe groups receiving concen trate supplementscompared with those receiving alfalfa supple-ments; however, DMD was greater (P<.01)for the LSAH group than for the AP group.The larger, coarser particles in the LSAHlikely would allow for longer ruminalretention time than for the AP, thus providingthe opportunity for increased ruminal disap-pearance of DM. Because all supplementgroups displayed increased (although vari-able) total DMI and DMD with increasingsupplementation, the digestible DMI alsoincreased (P<.01). Thus, even in those caseswhere substitution occurred, overall nutrientinput increased with increasingsupplementation level.

Ruminal dry matter fill measured justbefore feeding (0 h) for the SG/SBM 18%,SG/SBM 36%, and LSAH groups decreasedlinearly (P # .07) with increasing amount ofsupplement. The AP group tended (P = .11)to display the same trend. However, at 4hours after feeding, ruminal DM fill remainedfairly constant for the nonsupplementedgroup but increased substantially from the 0hour measurement for most groups receivingsupplement. Increases in ruminal fill, DMD,and possible increases in passage rate at leastpartially explain the ability of thesupplemented steers to increase the intake of


94

range forage compared with thenonsupplemented group.

Table 1. Effect of Supplemental Type and Amount on Forage Intake, Digestion, and Fill

Statistically

36% SG/SBM

18% SG/SBMAlfalfa Pellets Alfalfa Hay Significanta b

Item Ctrl. .05 .10 .15 .05 .10 .15 .05 .10 .15 .05 .10 .15 SEM Contrastsc

Hay DMI 1.15 1.46 1.59 1.71 1.34 1.48 1.33 1.39 1.47 1.54 1.17 1.22 1.09 0.07 1,2,4,5,8,10,d

%BW/d 11,12

Total DMI 1.15 1.60 1.89 2.15 1.60 2.05 2.17 1.66 2.00 2.35 1.44 1.76 1.90 0.07 1,2,4,5,6,8,11

%BW/d

DDMI 0.44 0.65 0.87 1.10 0.65 0.90 1.09 0.70 0.85 1.06 0.63 0.87 0.97 0.03 1,2,4,6,8,11e

%BW/d

DMD ,% 38.1 41.1 46.0 53.0 40.9 42.9 49.9 41.9 42.8 45.3 43.4 49.9 51.4 1.46 1,2,4,6,8,10,11f

DM fill

%BW

0 h 2.5 2.6 2.2 2.2 2.4 1.9 2.0 2.3 2.2 2.1 2.1 1.8 1.9 0.18 1,2,4,6

4 h 2.6 2.9 2.7 2.5 2.7 2.7 2.9 3.0 2.9 2.7 2.3 2.3 2.5 0.13 3,9,11

Liquid fill

%BW

0 h 15.6 16.5 15.2 12.4 14.8 14.3 12.8 15.0 14.9 14.6 14.4 14.0 14.1 0.88 2,3,4

4 h 16.2 17.6 16.4 14.0 16.1 15.2 15.2 17.1 17.6 16.2 16.4 16.4 16.7 0.78 2,3,12

SG/SBM = Supplement comprised of sorghum grain (SG) and soybean meal (SBM).a

Alfalfa pellets and hay were from the same source of alfalfa.b

Statistically significant (P#.10) contasts were: 1 = Supplemented vs nonsupplemented; 2 = Linear response for those receivingc

the SG/SBM 36% supplement; 3 = Quadratic response for those receiving the SG/SBM 36% supplement; 4 = Linear response

for those receiving the SG/SBM 18% supplement; 5 = Quadratic response for those receiving the SG/SBM 18% supplement; 6

= Linear response for those receiving the LSAH supplement; 7 = Quadratic response for those receiving the LSAH supplement;

8 = Linear response for those receiving the AP supplement; 9 = Quadratic response for those receiving the AP supplement; 10

= SG/SBM 36% vs SG/SBM 18%; 11 = AP vs LSAH; 12 = Concentrate supplements vs alfalfa supplements.

DMI = dry matter intaked

DDMI = digestible dry matter intakee

DMD = dry matter digestibilityf


Fort Hays Branch Experiment Station, Hays, KS.1


95


CONTINUOUS-CULTURE FERMENTATION AS ATOOL FOR FORAGE EVALUATION

E. S. Vanzan t , R. C. Cochran, K. C. Olson,1

S. Stafford, and G. St. Jean 2

Summary

Ruminal degradation of organic matterand protein in alfalfa and prairie hay wereevaluated in vivo, using can nulated cows, andin vitro, using a continuous-culture fermenterto simulate ruminal fermentation. Estimatesof organic matter degradability, microbial Nflow per unit feed N input, and efficiency ofmicrobial growth were not different (P>.10)between the in vivo and in vitro systems.However, for both forages, estimates ofnitrogen degradability were greater with thein vitro system. Despite the differencesbetween in vivo and in vitro techniques forsome variables, continuous-culturefermentation will allow us to compare theeffects of dietary treatments on foragedigestion and will aid in the formulation ofsupplements to meet specific nutrientrequirements for cattle consuming forage-based diets.

(Key Words: Alfalfa, Prairie Hay, RuminalDigestion, Protein.)

Introduction

The nutritive value of for ages to ruminantanimals depends on the extent to whichforage components are digested and utilizedwithin the rumen. Because measurement ofruminal digestion in the live animal presentsvarious difficulties, other approaches havebeen developed to simulate r uminal digestion.One such approach is the use of continuous-culture fermentation. With this technique,

ruminal microorganisms are maintained inglass fermentation vessels and are fed similardiets to those fed the live animal. Collectionof the materials flowing out of thefermentation vessels allows for calculation ofthe extent of degradation. This techniquedeserves particular attention as a means formeasuring forage protein degradation. Newprotein systems for cattle require knowledgeabout the quantity of dietary protein that isdegraded in the rumen and, consequently, thequantity that passes to the small intestinewithout degradation by ruminal micro-organisms. Most of the research in this areahas dealt with concentrates, particularlygrains and protein supplements. For cowsand stocker cattle that receive most of theircrude protein (CP) from forages, we havelittle information relating to the amount ofrumen degradable and nondegradable proteinin their diets. Thus, we ar e unable to assessaccurately their needs for supplementaldegradable and undegradable protein. Thisstudy was undertaken to evaluate the abilityof continuous-culture fermentation tosimulate ruminal fermentation of both high-and low-quality forages.


Degradation of alfalfa (16.8% CP) andprairie hay (5.8% CP) in continuous-culturefermenters was compared with in vivodegradation measurements obtained usingcannulated cows. The in vivo measurementswere made using six Angus × Hereford cowsthat had been fitted surgically with cannulas


96

in the rumen and duodenum. Samples werecollected from the diet, the rumen, and theduodenum and were analyzed for organicmatter; crude protein; and an internal marker,indigestible acid detergent fiber, whichallowed us to calculate the amount ofundegraded forage constituents flowingthrough the duodenum each day. Wemeasured the quantity of these constituentsderived from ruminal bacteria by determiningthe concentration of purine nitrogen in theduodenal contents and in bacteria that wereisolated from the rumen. By assuming thatall purine nitrogen at the duodenum comesfrom bacteria, we were able to determine theamount of organic matter and protein thatcame from bacteria. After estimatingcontributions to duodenal flow coming fromanimal cells and enzymes, the remainder ofthe flow through the duodenum was assumedto be undegraded forage constituents. Forthe in vitro technique, we fed each forageinto a continuous-culture fermenter, alaboratory apparatus designed to simulateruminal fermentation. The fermentercontained ruminal microorganisms harvestedfrom a ruminally cannulated steer andmaintained temperature, oxygen levels, andacidity within levels that allowed forcontinuous growth and digestion by theruminal microorganisms. The amounts oforganic matter and protein flowing into andout of the fermenter were measured, andmicrobial contribution was subtracted fromthe outflow as described above for the in vivotechnique.


The amounts of organic matter and CPfed are shown in Table 1. Estimated ruminaldigestibility of organic matter was greater(P<.01) for alfalfa than for prairie hay withboth techniques. Although the differencebetween the forages was numerically greaterwhen measured in vivo, differences betweentechniques were not significant. Aninteraction between forage type andmeasurement technique existed (P=.05) forestimated ruminal protein degradability,because protein degradability fo r alfalfa wassimilar between measurement techniques,

whereas it was significantly greater for the invitro technique with prairie hay. The flows ofnitrogenous constituents out of the respectivesystems were calculated as fractions of theamount of feed N put into each system toaccount for the fact that much greater totalamounts of N were required in vivo than invitro. The values for nonam monia N in Table1 represent a combination of N from bothmicrobial cells and undegraded feed. Thetotal nonammonia N flow out of each systemas a fraction of the feed N put into the systemwas greater (P<.01) for prairie hay than foralfalfa and was greater (P=.0 1) in vivo than invitro. The amount of bacterial N flowing outof each system as a fraction of the feed N putinto the system was also greate r (P<.01) forprairie hay than for alfalfa but was unaffected(P>.10) by the technique used . The large Noutflows for prairie hay as compared withalfalfa, when expressed as a percentage of Ninput, are indicative of the small amount ofruminally degradable N provided by theprairie hay. Nonammonia N outflow canexceed feed N input, as demonstrated by invivo outflow in excess of 100% of input forprairie hay. This is possible because ruminalbacteria utilize ammonia that is recycled backinto the rumen to synthesize bacterial protein.Efficiency of bacterial growth is measured bythe amount of bacterial N produced per kg oforganic matter digested in the system. Theefficiency of bacterial growth was unaffectedby either forage type or measurementtechnique.

The similarity between the techniqueswith respect to estimates of bacterial Nexiting the system as a proportio n of feed Nor per unit organic matte r fermented suggeststhat continuous culture can provide a rea-sonable estimate of the ability of a forage tosustain bacterial protein production. Thiswould allow us to predict the amount ofbacterial N available to the animal consuminga forage diet. Thus, the need for additionalruminally undegradable N could be assessed.Further study is necessary to determinewhether more accurate predictions of in vivoorganic matter and N degradability arepossible using our continuous culturefermenters.


97

In conclusion, specific values fordegradability of protein measured withcontinuous-culture fermentation did notmatch values obtained from in vivo mea-surements. However, continuous-culturetechniques provided a means to evaluatedifferences between the organic matter and

protein degradability of forage diets and al-lowed for prediction of bacterial proteinproduction supported by both high-qualityand low-quality forages. Use of these tech-niques will allow for more accurate formu-lation of supplements to meet the nutrientrequirements of ruminants consuming forage-based diets.

Table 1. Digestibility and Nitrogen Outflow for Alfalfa and Prairie Hay as Affected byMeasurement Technique

Alfalfa Prairie Hay P-valueb

Item invivoa

invitro

invivo

invitro SE F×T F T

Feed input, g/d

Organic matter 6337 13.5 6080 13.6 - - - -

Crude protein 1149 2.4 366 .8 - - - -

Digestibility , %c

Organic matter 61.6 60.5 45.9 53.9 3.73 .24 <.01 .36

Crude protein 83.0 90.7 54.1 75.5 3.26 .05 <.01 <.01

Nitrogen outflow, % of feed N input

Non-ammonia Nd 55.8 40.9 122.1 97.8 7.22 .53 <.01 .01

Bacterial N 38.8 31.5 76.2 73.4 7.42 .77 <.01 .51

Bacterial N flow, g/kg DOMe 17.8 16.2 16.5 14.1 2.56 .90 .54 .47

Measurement techniques: in vivo = measurements made using cannulated cows; in vitro = measurementsa

made using continuous culture fermenters. Probability of a greater F-value. F×T = forage type × measurement technique interaction; F = forage typeb

effect; T = measurement technique effect.Digestibility values for in vivo technique represent true ruminal digestibility (corrected for bacterialc

contribution).Nonammonia N corrected for estimated endogenous N flow with in vivo technique and, therefore,d

represents sum of bacterial N and undegraded feed N for both techniques.DOM = organic matter digested in rumen or fermenter, corrected for microbial organic matter.e


98


RELATIONSHIPS BETWEEN LIGNIN CONTENTAND FERMENTABILITY OF INTACT AND CHEMICALLY

TREATED BIG BLUESTEM FIBER

E. C. Titgemeyer, R. C. Cochran,G. Towne, and K. C. Olson

Summary

An accurate assessment of forage qualityis required to allow prediction of animalperformance. One of the most commonlyused methods of forage evaluation is tomeasure lignin content, with more heavilylignified materials being considered lessdigestible. Two measures of lignin, aciddetergent lignin (ADL) and acetyl bromidelignin (ABL), were assessed with regard totheir ability to predict forage digestibility.Big bluestem forage samples were collectedfrom three ungrazed, annually burnedpastures at 38, 58, and 97 days postburn.These times were selected to represent abroad range of forage quality. Cell wallmaterial was treated chemically by: 1) partialdelignification (chlorite), 2) isolation o f "-cellulose, or 3) NaOH extraction.

Control and treated cell-w all material wasanalyzed for ABL and ADL and 24 and 72 hrin vitro dry matter disappearance (IVDMD).ABL increased with advancing maturity forintact fibers, whereas ADL was highest in themost mature forage but lowest for theintermediate maturity. Fermentability of theintact fiber decreased with maturity and wascorrelated highly to ABL content. ABL wasa better indicator of forag e degradability forintact bluestem fiber than was ADL, butneither ABL nor ADL was adequate forevaluating fermentability of treated residues.

(Key Words: Big Bluestem, Forage Quality,Lignin.)

Introduction

An accurate assessment of forage qualityoften is required to allow pr ediction of animalperformance. One of the most commonlyused methods of forage evaluation is tomeasure lignin content, with more heavilylignified materials being considered lessdigestible. Lignin is a large polyphenoliccompound found in plants that not only isindigestible itself, but also reduces thedigestibility of other forage fractions.

Unfortunately, lignin is not a uniformentity, and, therefore, the laboratory tech-niques that are used to assess its concentra-tion are problematic. One of the mostcommon techniques for measuring lignin isthe acid detergent lignin (ADL) procedurethat uses strong sulfuric acid to degrade all ofthe nonlignin structures in the plant; ligninthen is calculated as the residue that remains.This technique typically underestimates thetrue lignin content because some of the ligninis solubilized by the strong acid. Anothertechnique for measuring lignin content is theacetyl bromide lignin (ABL) procedure thatsolubilizes lignin and subsequently measuresit spectrophotometrically. The biggestdrawback to this procedure is the difficulty infinding an appropriate standard to compare tosamples.

The objective of thi s experiment was toidentify changes in the lignin composition ofbig bluestem forage as it matures and torelate changes in lignin concentration todepressions in digestibility. We also sub-jected the forage to various chemical treat-ments in order to identify structures inbluestem that could limit digestibility.


99


Big bluestem was selected as represen-tative of warm-season grasses found in thenative range of Kansas. Samples of bigbluestem were collected from three ungrazed,annually burned pastures on the KonzaPrairie at 38, 58, and 97 days after the April24, 1993 burning. These times were selectedto represent a broad range of forage quality.Although the initial clipping was performedon June 1, the cold spring temperatures andslower than normal growth rate of the bigbluestem caused this sample to be quiteimmature.

Entire plants were clipped 1 cm above theground with clipping sites being marked toavoid collection of regrowth. Foragematerial was dried (50EC) and ground, andcell wall material was isolated by extractingwith hot (70EC) water for 1 hour.

Cell wall material was treated chemicallyby: 1) partial delignification (chlorite), 2)isolation of "-cellulose (treatment ofdelignified material with 2N KOH for 24 hr),or 3) sodium hydroxide extraction tosolubilize alkali-labile components andremove some of the core lignin (1N NaOHfor 24 hr). Control and treated cell-wallmaterial was analyzed for ABL, ADL, and 24and 72 hr in vitro dry matter disappearance(IVDMD).


The lignin concentrations of bluestem asmeasured by the ADL and ABL procedureswere quite different (Table 1); ABL yieldedmuch higher estimates than did ADL. This isprobably due to an underestimation of ligninby the ADL procedure, but could be partlydue to the use of an inappropriate standardfor the ABL procedure.

For the hot water extracted forage, ABLconcentration increased with increasingmaturity and was highly correlated to thedepression in 72 h IVDMD that wasobserved as the bluestem aged. ADL contentof the bluestem was more variable; althoughit was highest for the most mature sample, itwas lower for the intermediate maturity thanfor the first harvest date. The relationshipbetween ADL content and depressions ofIVDMD was not as strong as that for ABL.

For the chlorite-delignified and NaOH-treated residues, ABL content increased withincreasing maturity, mimicking the values forthe untreated residues. However, ADLconcentration in the chlorite-treated samplesdecreased with increasing maturity. Acrossmaturities, IVDMD of chlorite-delignifiedand NaOH-treated samples were greater thanthat of the untreated material, indicating thatthe phenolic constituents that weresolubilized played a significant role in thematurity-related decline in digestibility.

The cellulose residues should representthe largest single fraction within the plant cellwall. Typically, we believe that cellulose,when not encrusted by other cell wallmaterials like lignin, is highl y digestible. Withthe ABL procedure, no lignin was found inthe cellulose residues, whereas the ADLprocedure indicated that some ligninremained.

As plants matured, the digestibility of thecellulose residue decreased, indicating thatperhaps the size or crystallinity of thecellulose itself may limit digestion.

In conclusion, ABL was a bett er indicatorof forage degradability for intact bluestemfiber than was ADL, but neither ABL norADL was adequate for evaluatingfermentability of treated residues.


100

Table 1. Lignin Content and Digestibility of Big Bluestem and Chemically TreatedResidues

Date/Treatment ABL ADL 24h IVDMD 72h IVDMD

June 1, 1993 ----------------------- % of dry matter ------------------------

Water 15.12 4.63 15.5 63.6

Chlorite 7.33 2.68 38.9 67.8

Cellulose nd 2.73 34.6 84.5

NaOH 5.32 4.09 26.2 73.9

June 21, 1993

Water 16.89 4.23 16.5 57.6

Chlorite 8.35 2.22 28.2 64.2


NaOH 7.30 3.80 24.2 74.0

July 30, 1993

Water 21.04 5.23 11.6 47.8

Chlorite 10.95 1.61 26.2 73.9


NaOH 9.86 4.39 20.8 72.0

SEM .19 .25 3.0 2.4

ABL = Acetyl bromide lignin, ADL = Acid detergent lignin, IVDMD = In vitro dry matterdisappearance.Water = Forage soaked in 70EC water for 1 hour. Chlorite = Delignification with sodiumchlorite. Cellulose = Cellulose isolated from chlorite delignified residue by soaking in 2Npotassium hydroxide for 24 hours. NaOH = Forag e soaked in 1 N sodium hydroxide for 24hours.nd = Not detectable.


101


PUBERTY AND BREEDING PERFORMANCEOF BEEF HEIFERS DEVELOPED AT

DIFFERENT RATES OF GAIN

J. E. Minton, R. T. Brandt, Jr.,C. M. Coughlin, and R. C. Cochran

Summary

Crossbred heifers (546 lb initial bodyweight) were developed in drylot and limit-fed a corn, corn silage diet to gain .5 (n =14), 1.0 (n = 15), 1.5 (n = 14), or 2.0 lb/d (n= 15) from Dec. 7, 1992 unti l the onset of thebreeding season, May 3, 1993. Actual dailygains averaged 1.0, 1.4, 1.8, and 2.1 lb/d,respectively. Age at puberty was not affectedby feeding treatment. At the onset of thebreeding season, nutritional treatment had alinear effect on body condition score, ribeyefat thickness (both P<.01), and reproductivetract score (P<.05), all increasing withincreasing rate of gain. Nutritional treatmenthad a quadratic effect on pelvic area (P<.05),which averaged 190.6, 201.6, 206.5, and205.3 cm for heifers fed to gain .5, 1.0, 1.5,2

and 2.0 lb/d, respectively. At the conclusionof the development period, estrus wassynchronized, and heifers were inseminatedartificially at estrus for 45 days and, if open,mated naturally for another 17 d. Overallpregnancy rates were similar among heifersfed to gain .5, 1.0, and 1.5 lb/d (92.9, 93.3,and 92.9%, respectively), and all tended to begreater (P<.09) than the rate for heifers fed togain 2.0 lb/d (66.7%). In summary, NRCrecommendations underestimated gain oflimit-fed heifers at lower predicted rates ofgain. Thus, even though heifers fed to gainonly .5 lb/d had lower body condition scoresand reproductive tract scores at the onset ofthe breeding season, their actual body weightgains (1.0 lb/d) were sufficient for normalonset of puberty and subsequent conception.In addition, heifers fed to achieve relativelyhigh rates of gain (2.0 lb/d) during devel-opment may have had impaired fertility.

(Key Words: Beef Heifers, Puberty, HeiferDevelopment.)

Introduction

Numerous reports indicate that yearlingbeef heifers that are managed to conceiveearly in the breeding season have greaterlifetime productivity than heifers that con-ceive later. To increase the likelihood thatheifers will conceive early, they must haveattained adequate age and body weight to becycling before the start of the breedingseason.

A popular rule of thumb is that heifersshould be fed to attain 60 to 65% of theirestimated mature body weight by the start ofthe breeding season. Although severenutrient restriction during developmentdelays puberty, information is limitedregarding reproductive performance ofheifers developed to body weights somewhatbelow 65% of mature weight. Ifreproductive performance remained normal,developing heifers to lower prebreedingtarget weights could lower feed costs andreduce the potential for overconditioning,especially in smaller-framed heifers.

Our primary objective was to evaluateage at puberty and breeding performance ofheifers developed at different rates of gain.Treatments were designed to have heifersweighing 55 to 75% o f their expected maturebody weight by the onset of the breedingseason.


102


Angus × Hereford heifers were blockedby weight and assigned randomly withinweight blocks to four treatmen ts. Treatmentswere designed to produce body weight gainsof .5 (n = 14), 1.0 (n = 15), 1.5 (n = 14), and2.0 (n = 15) lb/d. Heifers were housed threeor four per pen, with four pens per treatment.Diets were formulated according to NRC(1984) recommendations to achieve thedesired rates of gain; the diet (as fed) was70% corn silage, 30% corn, and 3% of a vita-min-mineral supplement that suppliedRumensin® at 150 mg/hd/d. Enough soy-bean meal was topdressed daily to supplyprotein requirements for the desired gains.The feeding period began on Dec. 7, 1992and continued to May 3, 1993. Bodyweights, without shrink, were obtained every14 d.

Beginning on Feb. 15, serum sampleswere obtained on Monday, Wednesday, andFriday and analyzed for progesterone. Twoconsecutive samples with progesteroneconcentrations above 1 ng/ml indicatedovulation and luteal function; age at pubertywas defined as age at the sampling dateimmediately prior to the progesteroneincrease. Weight at puberty was the bodyweight closest to the age at puberty. Themeasured body weight was reduced by 4% toaccount for fill.

Body weight; body condition score (1 =extremely thin, 9 = extremely fat); ribeye fatthickness; pelvic area; and reproductive tractscore (1 = infantile uterus, 5 = mature,cycling, corpus luteum present) weredetermined at the conclusion of the feedingperiod. Then estrus was synchr onized by twoinjections of Lutalyse®, with the finalinjection on May 5. Heifers were inseminatedartificially at estrus using t he AM-PM rule forthe first 45 days. Then clean-up bulls wereused for 17 days. Pregnancy was verified byultrasonic evaluation of the uterus 36 daysafter the end of the breeding period.

Fasting heat production was calculatedretrospectively from the performance of the

heifers, utilizing NRC (1984) net energyequations.


The performance and reproductivecharacteristics of heifers fed to gain .5, 1.0,1.5, and 2.0 lb/d during development areillustrated in Table 1. Daily gains exceededNRC-predicted daily gains. Thisoverperfomance was generally greater atlower predicted rates of gain, which suggeststhat the performance predicted by the NRCbecomes increasingly inaccurate as calculatedgains are < 2 lb daily. This phenomenon maybe explained, in part, by the reducedmaintenance energy requirements of limited-fed cattle as reflected by reduced estimates offasting heat production (Table 1).

The major objective of this study was toevaluate reproductive performance of heifersentering the breeding season below thecurrently recommended 60 to 65% of theirexpected mature body weight. Because ourheifers gained faster than anticipated, evenheifers on the most restricted diet entered thebreeding season at approximately 63% oftheir expected 1100 lb mature body weight.Calculated percentages of mature bodyweight were 68%, 75%, and 78% for heifersfed to gain 1.0, 1.5, and 2.0 lb/d, respective-ly.

Age and weight at puberty were similaracross treatments. However, body conditionscores, ribeye fat thickness (P<.01), andreproductive tract scores (P<.05) allincreased linearly in response to increasedrates of gain. There was a qua dratic responseto treatment for pelvic area, which increasedfor heifers fed to gain between .5 to 1.5 lbper day but remained similar for heifers withpredicted gains of 1.5 and 2.0 lb/d.

By the onset of breeding, only one heifer(.5 lb/d treatment) was not pubertal, asestimated by serum progesterone . Thus, eventhough heifers on this treatment had lowerreproductive tract scores, all treatments, onaverage, had reproductive t ract scores of 4 orgreater, indicative of cyclicity. Based upon


103

our estimates of pubertal onset and reproduc-tive tract scores, all heifers were developedsufficiently to enter the breeding season.However, heifers in the 1.0, 1.5, and 2.0 lb/dgain treatments, although reproductivelycompetent, had increased body conditionscores and ribeye fat thickness, indicating thatthey may have been fatter than desirable.This degree of overconditioning may havedepressed the fertility of heifers fed to gain 2lb/d, as evidenced by thei r tendency (P<.09)for reduced pregnancy rates.

Our data suggest that NRC net energyequations underestimate the performance ofcattle at very low rates of gain. Althoughheifers fed to gain .5 lb/d had reduced bodycondition scores and reproductive tractscores, their body weight gains weresufficient to attain normal puberty and con-ception. In addition, overconditioning mayimpair fertility of heifers.

Table 1. Performance and Reproductive Char acteristics of Heifers Developed at Different Ratesof Gain

Predicted Daily Gain, lb

Item .5 1.0 1.5 2.0 SE

No. of heifers 14 15 15 15 -

Initial wt., lb 547 544 550 545 19

Prebreeding wt., lba 692 754 823 855 23

Daily gain, lba 1.0 1.4 1.8 2.1 .08

Fasting heat production,kcal/kg BW.75 b 62.7 66.8 66.1 84.1 4.8

Age at puberty, dc 386.6 374.1 373.6 385.6 9.8

Weight at puberty, lb 655 689 732 764 27

Body condition scored 5.7 6.1 6.6 6.8 .1

Fat thickness, ina .25 .25 .39 .47 .03

Pelvic area, cm 2 e 190.6 201.6 206.5 205.2 2.7

Reproductive tract scoref 4.0 4.2 4.5 4.5 .2

Pregnancy rate, %g 92.9 93.3 92.9 66.7 -

Linear effect of treatment (P<.01).a

Linear effect of treatment (P<.05).b

Sampling period immediately preceding two consecutive measures of serum progesterone greater than 1c

ng/ml. Linear effect of treatment (P<.01); 1 = extremely thin, 9 = extremely fat. d

Quadratic effect of treatment (P<.05). e

Linear effect of treatment (P<.05). Scale of 1 to 5; 1 = infantile, prepubertal, 4 = cycling, but no corpusf

luteum present, 5 = cycling, but corpus luteum present.Estimated ultrasonographically 36 d after the conclusion of the breeding period; lower for heifers fed tog

gain 2.0 lb/d (P<.09).


Appreciation is expressed to Gary Johnson, Dwight, KS, for the commercial heifers used1

in this study.

Sincere thanks to Paul Zuhkle, Kelly Griffin, and the crew at the purebred unit for their2

assistance in conducting this experiment. Thanks also to Todd Milton for statistical assistanceand Colleen Coughlin for lab assistance.

104


INFLUENCE OF DIETARY ENERGY LEVELS ONREPRODUCTIVE FUNCTION AND FERTILITY

IN YEARLING BEEF HEIFERS 1,2

S. D. Utter and L. R. Corah

Summary

Fifty-nine heifers were allotted to be fedat two different energy levels. One groupgained 1.77 lb/hd/day, and the other 1.25lb/hd/day. Estrus was synchronized with theMGA/prostaglandin system. After MGAremoval, ovarian developmen t was monitoreddaily by ultrasound (10 per group) untilestrous was detected following the PGFinjection. Heifers were inseminated artifi-cially based on estrus behavior. Fastergaining heifers had higher final body condi-tion scores and greater changes in body con-dition score. The high energy diet caused aslight (P=.11) decrease in AI pregnancy ratefor purebred heifers.

(Key Words: Beef Heifers, Energy Levels,Ovarian Function, Fertility.)

Introduction

Proper development of replacementheifers can improve reproductive efficiency.Heifers that conceive early in the breedingseason tend to rebreed t he following year andhave a more productive lifetime. Dietarymanagement can influence the reproductiveefficiency of heifers. Underfeeding has longbeen recognized as detrimental toreproductive efficiency, but the impact ofoverfeeding has not been studied extensively.

Our purpose was to determine the influenceof two levels of dietary energy on expressionof estrus, ovarian function, concentrations ofprogesterone, and corresponding AIconception rates.


Fifty-nine heifers (40 commercial, 19purebred) were stratified by weight and bodycondition score (BCS) within breed into twodifferent treatments. Heifers were targeted togain 3.3 lb/hd/day (excess) or 1.2 lb/hd/day(optimum). Estrus was synchronized byfeeding MGA for 14 days, with a prostaglan-din injection 17 days after removing MGA.From the time MGA was withdrawn untilbreeding, the ovaries of the 19 purebred heif-ers were scanned daily by transrectalultrasonography. Blood samples werecollected daily in the scanned heifers todetermine progesterone concentration. Fromthe scans, the corpus luteum and number andsize of follicles were counted and scored asmedium (5 to 10 mm diameter) or large (>10mm). The size of the ovulatory follicle alsowas recorded. Both commercial andpurebred heifers were inseminated artificiallybased on observed estrus. Commercialheifers then were placed with a bull for theremainder of the breeding season, whereasthe purebred heifers continued to be insem-inated for an additional 45 days, then were


105

placed with a bull for an additional 10-days.Pregnancy determination and calving datawere used to calculate conception date.


Heifers targeted to gain 3.3 lb/hd/dayactually gained only 1.77 lb/hd/day. Heiferson the optimum energy level were targeted togain 1.2 lb/hd/day and actually averaged 1.25lb/hd/day. These averages were diminishedbecause the purebred heifers lost weightduring the scanning period. Although thedesired average daily gain was not achieved,excess energy increased (P<.01) final averagedaily gain, final body condition score, andchange in body condition score for bothcommercial and purebred heifers (Table 1).

Dietary energy level had no effect onserum progesterone concentrations, folliculardevelopment, or CL size at the time ofprostaglandin injection (Table 2).

Excess energy decreased AI pregnancyrates (P=.11) in purebred heifers but had noeffect in commercial heifers. Combiningresults for the purebred and commercialheifers resulted in a decrease in first-serviceconception rates for heifers on the excessenergy level (Table 3).

Serum progesterone concent rations in thepurebred heifers are shown in Figure 1. Al-though no treatment effects occurred theprogesterone profile illustrates the expectedresponse following MGA feeding and aninjection of prostaglandin.

Table 1. Average Daily Gain and Body Condition Scores for Purebred and CommercialHeifers Fed Excess or Optimal Dietary Energy Levels

Trait Excess Energy Optimum Energy

Purebred heifers (n=19) Overall average daily gain 1.41 1.03a

Final body condition score 5.8 5.4a

Change in body condition score .50 -.14Commercial heifers (n=39) Overall average daily gain 1.98 1.41b

Final body condition score 6.5 5.7b

Change in body condition score 1.00 .24b

Overall heifer averages Overall average daily gain 1.77 1.25 Final body condition score 6.3 5.4 Change in body condition score .89 .12Different (P<.01) from optimum energy treatment.a

Different (P<.05) from optimum energy treatment.b

Table 2. Influence of Dietary Energy on Concentration of Progesterone in Serum,CL Size, and Number and Size of Follicles

Excess OptimumItem Energy Energy P-value

Prior to prostaglandin inj. Progesterone level (ng/ml) 3.3 3.6 .7 Diameter of CL (mm) 20.9 19.4 .4 No. of medium and large follicles 3.7 2.9 .25 Diameter of largest follicle (mm) 9.3 7.9 .24At time of AI breeding No. of medium follicles 3.0 2.0 .19 Diameter of ovulatory follicle 10.9 10.3 .62


Table 3. Influence of Dietary Energy Levels on Response to Synchronization, AIConception, and Overall Pregnancy Rates

Treatment

Excess EnergyPurebredCommercialCombined

Optimum EnergyPurebredCommercialCombined

% Response to % ConceivedSynchronization through AI

7/10(70%) 3/7 (42.3%)18/19 (94.7%) 13/l8 (72.2%)25/29 (86.2%) 16/25 (64.0%)

7/9 (77.8%) 6/7 (85.7%)19/20 (95.0%) 15/19 (79.0%)26/29 (89.7%) 21/26 (80.8%)

% OverallPregnancy

9/10(90%)18/19 (94.7%)27/29(93.1%)

9/9 (100%)20/20 (100%)29/29 ( 100%)

Figure 1. Average Progesterone Levels by Treatment for Purebred Heifers duringUltrasound Scan Period

1 0 6


Sincere appreciation is expressed to Heartland Cattle Company for providing the data set1

used in this analysis. Heartland Cattle Co., McCook, NE.2


Department of Statistics.4

107


FACTORS INFLUENCING FIRST-SERVICECONCEPTION AND OVERALL PREGNANCY RATES

IN COMMERCIAL BEEF HEIFERS 1

S. D. Utter, P. L. Houghto n , L. R. Corah,2

D. D. Simms, M. F. Spir e , and M. D. Butine3 4

Summary

Commercial beef heifers (n=1863) from16 different sources were used to evaluatethe influence of management practices andbiological traits on first-service conceptionand overall pregnancy rates. Frame score,initial weight, overall ADG, body conditionscore, reproductive tract score, source, AItechnician, and AI sire signifi cantly influencedfirst-service conception. Overall pregnancyrates were influenced by frame score, bodyweight, and ADG.

(Key Words: Beef Heifers, First-ServiceConception, Pregnancy Rates.)

Introduction

Proper evaluation, selectio n, and manage-ment of replacement heifers are critical to theproduction and longevity of females in thecow herd. Heifers that c onceive early in theirfirst breeding season have a greater potentialto rebreed as cows, ensuring continuedproduction in the herd. Our objective was toevaluate the influence of management andbiological parameters on first-service con-ception and overall pregnancy rates in heifers.


To evaluate the effect of various manage-ment practices and biological traits on first-service conception and overall pregnancyrates, 1,863 heifers from six states and 16sources were developed postweaning at acommercial heifer development facility inSouthwest Nebraska. Initial body weight wasmeasured when heifers entered the facility inearly to mid-winter. A high roughage rationwas limit-fed at a level so heifers would reach65% of their projected mature body weightbefore the breeding season began. Pro-duction data collected 35 to 40 days pre-breeding included frame score, reproductivetract score (1=highly developed, 6=infantile),and body condition score (1= thin, 9=obese).

The heifers were placed on a higher planeof nutrition 33 days before breeding. Thatplane was maintained through the first 21days of the breeding season. Heifers weresynchronized by feeding .5 mg/hd/day melen-gesterol acetate (MGA) for 14 days, followedby a subcutaneous injection of prostaglandin(Bovilene®) 14 days after MGA withdrawal.A breeding body weight was measured at thetime of injection. Heifers were inseminatedartificially approximately 12 hours afterestrus was first detected. Nonresponderswere reinjected 9 days afte r the first injection.If no estrus was observed a fter a third prosta-glandin injection, heifers were inseminated at


72 hours post injection. First-service concep-tion and overall pregnancy rates weredetermined by ultrasonography 35 to 45 daysafter the end of the 45-day breeding season.A final body weight was measured at thattime. The difference between initial weightand final weight was used to calculate overallaverage daily gain (ADG).

A specialized statistical analysis (con-tingency tables) was used that allowed us toexamine the influence of a single managementfactor or biological trait, while others wereheld constant. Because of the significantinfluence of heifer source, a separate analysisof heifers from a single source (n=507) wasperformed. A second statistical approach(mixed-model analysis) was used for theentire population (n=1863) to reduce theinfluence of source, technician, and sire.


As frame score increased, first-serviceconception (P=.16) and overall pregnancyrates (P<.10) tended to decrease (Figure 1).The contingency table analysis showed thatheifers that gained 1 to 1.5 lbs/day had thehighest first-service conception rates

Overall, heifers with frame score, bodywt, body condition score, and ADG in the“moderate” range were more reproductivelyefficient. In addition, several factors interactto influence reproductive efficiency,demonstrating the importance of managing allcontributing factors, rather than focusing onvery few.

Figure 1. Influence of Frame Score on First-Service Conception

(Figure 2) and overall pregnancy rates(Figure 3). Daily gains above and below thisrange produced lower (P<.01) pregnancyrates. A quadratic response was observed asbody condition score increased (P<.10), witha decline in first-service conception in eitherextremely thin or fat heifers (Figure 5).Reproductive tract score tended (P=.17) toinfluence first-service conception but notoverall pregnancy rates (Figure 4). Heiferswith infantile tracts, designated by a score of6, had the lowest first-service conceptionrates when compared to those with scores of1 through 5. The mixed model analysis foundthe fixed effects of body condition score(P<.0l; Figure 4) and reproductive tractscore (P<.0l; Figure 5) to be significant.Interactions among ADG, frame score,breeding wt, prebreeding wt, body conditionscore, and reproductive tract score weresignificant, illustrating the impact o fnumerous factors on first-service conception.

108


Figure 2. Influence of Overall Average Daily Gain on First-Service Conception

Figure 3. Influence of Overall Average Daily Gain on Overall Pregnancy Rate

1 0 9


Figure 4. Influence of Body Condition Score on First-Service Conception

Figure 5. Influence of Reproductive Tract Score on First-Service Conception

110


111


RESTRICTING CALF PRESENCE WITHOUTSUCKLING SHORTENS POSTPARTUM INTERVAL

TO FIRST OVULATION

D. P. Hoffman and J. S. Stevenson

Summary

The suckling interaction between a cowand her calf is one of the factors that main-tains a cow in postpartum anestrus (theperiod between calving and the beginning offirst estrous cycle). Anestrus continues if thecow perceives that her calf is attempting tonurse, even when the mammary glands havebeen denervated or removed. Cr oss-fosteringof an alien calf to a cow fails to maintainpostpartum anestrus, indicating that cow-calfrecognition is also a factor. We restrictedcalves so they could nuzzle the cow's headand neck but could not suckle. Comparedwith weaning calves 1 wk postpartum,restriction lengthened the interval to firstpostpartum ovulation but less than withnormal suckling. These results suggest thatmaintaining cow-calf recognition in the ab-sence of the suckling stimulus is an essentialpart of the nursing mechanism that prolongsanovulation. Thus, blocking the cow's recog-nition of her calf might further decrease thepostpartum interval to first ovulation.

(Key Words: Suckling, Anestrus, EstrousCycles, Postpartum.)

Introduction

Reproduction is a critical factor limitingproduction efficiency in the beef cow. Failureof the cow to become pregnant during thebreeding season l imits the potential calf crop.To improve reproductive efficiency, thepostpartum interval (time from parturition tofirst ovulation) needs

to be reduced. The suckling stimulus is animportant component in lengthening thepostpartum period of anestrus.

Cows whose calves were weaned at birthhad shorter intervals to first ovulation thancows that were suckled. Cows with non-suckling (muzzled or nose-plated) calves hadlonger intervals to first postpartum estrusthan with cows whose calves were weaned.Suckled cows with denervated udders,maintained with their calves, had intervals tofirst postpartum estrus similar to those ofintact cows maintained with their calves.

Mastectomized (udder removed) cowswith their calves present had intervals to firstpostpartum ovulation similar to those ofudder-intact cows with their calves, indicat-ing that presence of the mammary glands wasnot essential for prolonging anestrus in beefcows. Mastectomized cows whose calveswere restricted so they could not attempt tosuckle cycled about 7 d later thanmastectomized cows whose calves were re-moved at birth.

Cows with cross-fostered calves c ycled asearly as cows whose calves were weaned,suggesting that the cow must perceive herown calf to be suckling in order to prolongpostpartum anestrus. The objective of ourexperiment was to determine how restrictingthe calf to head and neck conta c t with its damwould alter the onset of postpartum estrus inudder-intact beef cows.


112


Twenty-four multiparous, crossbred,Angus, cow-calf pairs were assigned ran-domly to three groups: 1) calves had normalunrestricted contact with their dams (calfpresent; CP); 2) at 7 days (±3) of age calveswere placed in a small individual pen withinthe dam's individual pen where the calf couldmake tactile contact to its dam's head andneck but could not suckle (calf restricted;CR); and 3) calves were weaned permanentlyfrom their dams 7 days (±3) after birth (calfweaned; CW). Calves in the CP and CRtreatments were weaned permanently when42 days (±3) old.

Cows were fed according to NRCrecommendations based on weekly individualbody weights of each cow. The CP cowswere fed as superior milk producers and theCR and CW cows were fed as dry second-trimester, pregnant, beef cows. Calves in theCR treatment were bottle-fed milk replacertwice daily. The cows

were removed twice daily from their pens forexercise, at which time they were observedfor signs of estrus. Blood was collected dailyto assess changes in serum progesterone.


Postpartum intervals to f irst ovulation aresummarized in Table 1. The postpartuminterval to first ovulation was shorter (P<.01)in the CW (21.5 ± 2.4 d) than the CP treat-ment (42.5 ± 2.2 d). This same response wasobserved in previous experiments usingsimilar treatments but mastectomized cows.The CR cows had intervals to first ovulation(29.1 ± 2.2 d) between those for CP and CRcows, but different (P<.01 ) from both. Theseresults suggest that maintaining cow-calfrecognition in the absence of suckling by thecalf is an essential part of the mechanism thatprolongs anovulation. Thus, blocking thecow's recognition of her calf might furtherdecrease the postpartum interval to firstovulation.

Table 1. Average Intervals to First Postpartum Ovulation in Beef Cows withEither Calf Presence, Restricted Calf Presence, or No Calf

Treatmenta No. of Cows Interval, d

Calves weaned (CW) 7 21.5 ± 2.4x

Calves restricted (CR) 8 29.1 ± 2.2y

Calves present (CP) 8 42.5 ± 2.2z

At d 7 (±3) postpartum, calves were weaned from their dams (CW), restricted to head anda

neck contact with their dams (CR), or allowed unlimited contact with their dams (CP). Calvesin CR and CP treatments were weaned at d 42 (±3) postpartum.

Average intervals with uncommon superscript letters are different (P<.01).xyz


Appreciation is expressed to Kansas Artificial Breeding Service Unit, Manhattan, KS, for1

semen collection and evaluation and Select Sires, Inc., Plain City, OH for assessment of spermmorphology. Senior Lilly Scientist, Lilly Research Labs, 804 Anderson, Garden City, KS.2

113


EFFECT OF MONENSIN ON WEIGHT GAIN,GROWTH TRAITS, AND SEMEN CHARACTERISTICS

IN YEARLING BEEF BULLS 1

C. W. Peters, S. B. Lauder t , L. R. Corah,2

D. A. Nichols, and C. L. Krehbiel

Summary

Feeding the ionophore monensin toyearling beef bulls improved (P<.05) weightgain by 4.2%. Final hip height was similarbetween treatments, but bulls fed monensinhad almost 1 cm greater (P<.01) scrotalcircumference and more than 10 cm larger2

(P<.01) pelvic area. Semen characteristicsgenerally were unaffected by treatment.However, bulls fed monensin had less(P<.01) semen motility than controls.Approximately 30 sperm morphology traitswere evaluated; values were similar betweentreatments except for those traits listed.Collection date tended to influence (P<.15)volume, concentration, motility, andpostfreeze characteristics.

(Key Words: Bulls, Performance, Monensin,Semen, Ionophore, Morphology.)

Introduction

The ionophore monensin has been usedwidely to improve gain and feed conversionby beef cattle. The vast majority of finishingcattle and many stocker cattle are fed anionophore to improve perfor mance. Previousresearch has suggested that the onset ofpuberty is hastened in developing heifers fedmonensin. The objective of this trial was toevaluate the impact of monensin on weightgain, growth traits, and semen characteristicsin yearling beef bulls.


Forty-four, spring-born, yearling bullswere allotted by weight, breed, sire, andbirthdate and assigned randomly to each oftwo dietary treatments: 1) a 13.5% crudeprotein control supplement consisting ofcorn, oats, and soybean meal (CON); or 2)the control supplement plus the ionophoremonensin (Rumensin®) fed at 200 mg perhead per day (RUM). Each treatment groupcontained 15 Angus, five Hereford, and twoPolled Hereford bulls. Bulls averaged 838 lbat the beginning of the trial. They wereweaned approximately on September 15 andfed the control supplement and hay ad libitumuntil 2 weeks prior to the start of the trial(December 14). Bulls fed monensin wereallowed a 4-day warm-up period withmonensin fed at 100 mg per head per day.All bulls were housed in dry lot; theremainder of the diet was native prairie hayfed ad libitum.

Data collection. Averages of twoweights on consecutive days at the beginningand end of the trial were used as initial andfinal weights. Hip heights and scrotalcircumferences were measured at thebeginning and end of the trial. Measures ofpelvic area and breeding soundnessevaluations were made at the end of the trial.Semen was collected twice during the last 3weeks of the trial using restrained cows andan artificial vagina. Bulls whose semen was


114

not collected successfully on the first attemptwere tested again 21 days later; bulls whosesemen was not collected su ccessfully with theartificial vagina were subjected to electro-ejaculation. Raw semen was processed onsite, and ejaculate volume, sperm motility,and sperm concentration were determined.At the Kansas Artificial Breeding ServiceUnit, cryopreservation was attempted with allsuccessful collections. Semen remainedfrozen for 24 hours before sperm morphologywas further evaluated immediately postthawand after incubation for 2 to 4 hours.


Overall weight gain and average dailygain were greater (P=.03) for bulls fed RUMcompared to CON (Table 1). At thebeginning of the trial, hip height and scrotalcircumference were similar betweentreatments. Final hip height did not differbetween treatments, but measure-

ments of scrotal circumference and pelvic a-rea were greater (P<.01) for bulls fed RUM.

Semen collection data are presented inTable 2. Semen was collected from more(P=.06) bulls fed CON on the first attemptthan from bulls fed RUM. However, nodifferences existed in the number from eachtreatment whose semen was collectedsuccessfully by artificial vagina.

The morphological abnormalities thatapproached significance (P<.15) are listed inTable 3. Detailed are the number of bullsfrom each treatment that possessed eachparticular abnormality. Also presented is thepercentage of abnormal sperm for traits thatapproached significance (P<.15). Noconsistent differences were present betweentreatments. Further analysis revealed thatcollection date (first or second attempt) hada greater (P<.10) influence on semencharacteristics than dietary treatment.Feeding RUM promoted greater weight gainand enhanced growth traits in yearling bulls,with no general effect on semen traits.

Table 1. Effect of Monensin on Weight Gain and Growth Traits in Yearling Beef Bulls

Item Control Monensin SE Significancea

Final wt, lb 1208 1222 8 .23Total wt gain, lb 371 386 5 .03Avg daily gain, lb/d 3.64 3.78 .05 .03Initial hip height, in 46.3 46.1 .1 .39Hip height change, in + 4.1 + 4.3 .1 .12Initial SC , cm 29.2 29.2 .2 .95b

Final SC, cm 34.8 35.7 .2 .01Pelvic width, cm 11.0 11.4 .1 .01Pelvic height, cm 14.4 14.8 .1 .01Pelvic area, cm 158.9 169.1 1.1 .012

Probability associated with treatment effect.a

SC=scrotal circumference.b


115

Table 2. Effect of Monensin on Collection and Semen Characteristics in Yearling BeefBulls


BSE 84.6 86.8 2.9 .59b

Volume, ml/ejaculate 2.69 3.11 .26 .27

Concentration, % 64.0 69.9 2.9 .16

Motility, % 45.8 34.6 3.3 .02

Collected on first date 11/22 5/22 .06

Collected by AV 19/22 18/22 .68c


BSE=breeding soundness examination score.b

AV=artificial vagina.c

Table 3. Effect of Monensin on Sperm Morphology in Yearling Beef Bulls


Number of bulls producing sperm with respective abnormality

Tapered heads 15 18 .04

Asymmetrical heads 12 12 .82

Diadem (equatorial craters) 6 2 .13

Head and tail separated 19 16 .14

Protoplasmic droplets 11 15 .09

Percentage of sperm possessing abnormality

Tapered heads 3.27 4.89 .70 .11

Asymmetrical heads 2.42 1.50 .43 .14

Diadem (equatorial craters) 4.67 1.00 1.5 .15

Head and tail separated 4.16 5.19 .88 .42

Protoplasmic droplets 6.36 10.73 4.05 .45



Department of Animal Science, Louisiana State University, Baton Rouge, LA.1

116


AMONG-BREED ESTIMATES OF HERITABILITYFOR BIRTH WEIGHT, WEANING WEIGHT, AND

MATURE COW WEIGHT

K. M. Andries, R. R. Schalles, and D. E. Franke1

Summary

Data from a rotational crossbreedingstudy was used to calculate among-breedheritabilities of birth weight (BWT), weaningweight (WWT), and mature cow weight at 5years of age. The among-breed estimateswere higher than previous within-breedestimates because of the inclusion of geneticdifferences between breeds. Maternal effectsfor BWT and WWT also were calculated.These estimates allow for comparisonsamong breeds and for the eventual calculationof EPDs for hybrid cattle.

(Key Words: Heritability, Birth Weight,Weaning Weight, Cow Weight.)

Introduction

The wide-scale use of crossbreeding andincreased number of available breeds requirescomparison between breeds. With theanalysis procedures currently being used bybreed associations, direct comparisonsbetween breeds are not possible withoutadjusting the EPDs. The purposes of thisstudy were to produce estimates ofheritabilities and correlations among breedsand to increase the data available for use inbreed comparisons. These data also willallow for the calculation of EPDs for hybridcattle. This study is part of the NC-196national project to study the genetics of bodycomposition of beef cattle.

Experimental Procedure

Data collected between 1970 and 1988 atLouisiana State University, Baton Rouge,were used for the analysis of birth weight(BWT), weaning weigh t (WWT), and maturecow weight (COWWT) taken at 5 years ofage. The data set consisted of 3936 BWT,3611 WWT, and 627 COWWT records. Thedata were from generations 1 through 4 of arotational crossbreeding study involvingAngus, Brahman, Charolais, and Hereford.Straightbred and crossbred data were in-cluded in the analysis. Cows were bred bynatural service to calve between January 15and April 10. Calves were dehorned, ifneeded, and weighed and ear notched within24 h of birth. All bull calves were castratedin July. Calves were wean ed in the first weekof October at an average age of 220 days.Cows were weighed when the calves wereweaned.

Cows were wintered on Bermudagrasshay and ryegrass pastures from Novemberthrough March. Bermudagras s pastures weregrazed during the spring and summer.Replacement heifers were kept from withinthe herd and managed similarl y to the cows.All bulls were purebred and purchased frombull test stations or private sales.

The models used for this analysi s includedcontemporary group (same year of


117

birth and sex) and percent heterosis for allthree traits. The BWT and WWT analysesalso included age of dam and a regression forbirth date or age at weaning, respectively.The cow weight analysis included theproduction status of the cow in her fifth year(weaned a calf, calf died preweaning, oropen). Maternal influences also werecalculated for BWT and WWT. The pedigreeinformation was included in an animal model.


The averages (lb) were 72.6 for BWT,497.2 for WWT, and 1082.1 for COWWT.Heritabilities and correlations are shown inTable 1. The heritability for BWT (.87) ishigher than previously reported values,primarily because the value is an among-breed rather than a within-breed estimate.Heritabilities for WWT (.48) and COWWT(.81) were high, but more similar to within-breed estimates found in the literature. Thehigh heritabilities for all three traits indicatethat change can be made through selectionamong as well as within breeds in all traits.

The correlations between BWT andWWT were high (genetic = . 79, phenotypic =.50), indicating that both traits should beconsidered in selection. These correlationsindicate the need to keep BWT in a rangethat allows for reasonable calving ease, whileproducing acceptable WWT. Thecorrelations between COWW T and the othertwo traits were zero, which indicates thatselection for acceptable early weights will notnecessarily have a direct influence on matureweight of cows. We believe that rate ofmaturity is one factor influencing thisrelationship.

Maternal heritability indic ates the influence ofthe dam's genetics on the weight o f her calf,apart from the genes she passed on. ForBWT, maternal heritability primarily reflectsthe uterine environment, whereas for WWT,it reflects milking ability. The correlationbetween maternal and direct BWT was -.22,indicating a compensation by the dam toreduce the BWT of calves that have a highdirect genetic value for BWT. This negativecorrelation was present even when thepercent of Brahman in the dam was includedin the analysis.

The analysis included the variationbetween breeds as well as within breeds.This allowed for calculation of among-breedheritabilities and correlations. We expectedthese estimates to be higher than the within-breed estimates because of the geneticdifferences between breeds. These valuesallow for comparisons among the breeds inthe study. The high correlation betweendirect BWT and WWT shows the need toselect for moderate BWT in order to achieveacceptable WWT. The high among-breedheritability of BWT indicates that it can becontrolled by selection of breeds as well asindividuals within a breed. The negativecorrelation between direct and maternal BWTshows the importance of not relying totallyon actual weight to determine geneticpotential of an animal. The results of thisstudy can be used to produce EPDs forhybrid cattle in the future.


Table 1. Heritabilities and Correlations of Weight Traits a

Direct

Birth Weaning Mature

Trait wt wt wt

Direct

Birth wt .87 .50 0

Maternal

Birth Weaning

wtb wtb

Weaning wt .79 .48 0

Mature wt 0 0 .81

Maternal

Birth wt -.22 0 0 .26

Weaning wt 0 0 0 0 .18aHeritabilities are underlined, genetic correlations are below heritabilities, and phenotypic

correlations above.bPhenotypic correlations were not calculated for maternal effects.

Heritabilities and Genetic Correlations

Direct heritabilities estimate the fraction of variation among animalscaused by genes received from the parents, and range from zero to 1. Thedam also provides a maternal environment, such as uterine environment andmilking ability which is influenced by the dam's own genetics, separate from thegenes she passes on to the offspring. The heritability of this maternalenvironment is referred to as maternal heritability. Direct heritabilities includea calf's own genetics for growth up to birth, expressed as birth weight heritabilityor growth to weaning, expressed as weaning weight heritability, etc.

Correlations indicate the relationship between two traits and canrange from -1 to +l.Genetic correlations indicate the relationship between twotraits caused by the same genes. For example some genes that cause rapid growthfrom birth to weaning also cause rapid growth from weaning to yearling. Somegenetic correlations are less obvious. A correlation between maternal weaningweight and direct yearling weight would indicate that some of the genes thatinfluence milk production also influence the individual's own growth rate.

118


119


HERITABILITIES AND GENETIC CORRELATIONSFOR BIRTH WEIGHT, WEANING WEIGHT, AND

YEARLING WEIGHT IN POLLED HEREFORD CATTLE

J. B. Glaze and R. R. Schalles

Summary

Performance data from a Polled Herefordherd selected for feed conversion were usedin the calculation of heritabilities and geneticcorrelations for birth wei ght (BWT), weaningweight (WWT), and yearling weight (YWT).Direct heritabilities for BWT, WWT, andYWT were .31, .16, and .25, respectively.Corresponding maternal heritabilities forBWT, WWT and YWT were .04, .01, and.18, respectively. With the exception of thecorrelation between WWT and YWT (.98),the other genetic correlations were low tomoderate, ranging from -.27 to .12.

(Key Words: Birth Weight, WeaningWeight, Yearling Weight, Heritabilities,Genetic Correlations.)

Introduction

Traditionally, beef cattle producers havemarketed their product on the basis ofweight. This has led to an increased em-phasis on growth traits, such as birth weight,weaning weight, and yearling weight, inselection programs. For producers to makethe most of their selection programs, theymust have an understanding of the geneticrelationships between traits. Therefore, thepurpose of this study was to estimate theheritabilities and genetic correlations of birthweight, weaning weight, and yearling weight.


Performance data were collected on 1410animals from a Polled Hereford herd atKansas State University, from 1967 through1979. This herd was assembled using animals

that were donated by breeders from severalstates and represented a cross sectio n of thePolled Hereford breed. Calves from theoriginal herd were used to establish aselection herd. The original herd then wasused as a nonselected control. Bulls andheifers were selected from within each herd.Two bulls were selected based on feedconversion (high conversion) and used for 2consecutive years in the selected herd. Onebull was randomly selected in the controlherd and used as a herd sire forapproximately 6 years.

Cows representing the selected andcontrol herds were maintained on nativepasture throughout the year and were sup-plemented in the winter. Cows were bred tocalve in March and April, with calves beingweaned in the fall at an average age of 196days. Bull calves were placed on aperformance test, which allowed for selectionfor feed conversion and individuall y fed 140days. Heifers were group fed and were notselected on the basis of feed conversion.Cows were culled according to the following:(1) open at the end of the breeding season,(2) severe structural problems, and (3)horned. Birth weight (BWT), weaningweight (WWT), and yearling weight (YWT)records were available for analysis. Thenumber of observations, means, and standarddeviations for each trait are presented inTable 1. Subsets of this data set have beenanalyzed previously using paternal half-sibanalysis procedures. However, with theadvent of new technologies, the relationshipsbetween animals were incorporated into theanalysis.


120

A derivative-free, restricted maximumlikelihood procedure, incorporating a fullnumerator relationship matrix, was used toanalyze the data. The mixed linear animalmodel included age of dam (2, 3, 4, 5-10, and>10 yr) and contemporary group (sex andyear of birth) as fixed effects. Birth date, ageat weaning, and age at ye arling were includedto regress all records to the respective meanages. Individual animal effect, maternaleffect, and permanent environmental effectwere included as random effects.


Heritabilities and genetic correlations forBWT, WWT, and YWT are presented inTable 2. The direct heritability for BWT(.31) is similar to those previously reported,whereas direct heritabilities for WWT (.16)and YWT (.25) are lower than previously re-ported estimates. The mater-

nal heritabilities for BWT (.04) and WWT(.01) indicate that the genetic maternalinfluence on these traits is small, whereas thematernal heritability for YWT (.18) indicatesa moderate genetic maternal influence. Thestrong positive genetic correlation betweenWWT and YWT (.98) indicates that many ofthe same genes affect both traits, and may bedue to the part-whole relationship of thetraits. The genetic correlation (-.27) betweenmaternal birth weight and maternal weaningweight indicates that animals having a geneticuterine environment that increases birthweight tend to have the genetics for lowermilk production, and vice versa. Geneticcorrelations between other traits were low,ranging from -.06 to .12. Another project iscurrently under way to examine t he direct andcorrelated responses due to selection for feedconversion and to estimate heritabilities andgenetic correlations of additional traits.

Table 1. Number of Observations, Means, and Standard Deviations for Each TraitAnalyzed

Trait n Mean SD

Birth wt, lb 1369 73.25 9.63

Weaning wt, lb 1284 383.82 68.24

Yearling wt, lb 1045 715.07 145.45

Table 2. Heritabilities and Genetic Correlations for Each Trait Analyzeda

Direct Maternal

Trait BWT WWT YWT BWT WWT YWT

Direct

Birth wt .31

Weaning wt .12 .16

Yearling wt .00 .98 .25

Maternal

Birth wt -.03 -.02 .00 .04

Weaning wt -.06 .09 .00 -.27 .01

Yearling wt .00 .00 .00 .00 .00 .18

Heritabilities are underlined; genetic correlations are below the heritabilities.a


Div. Anim. & Veterinary Sci., West Virginia University, Morganstown, WV.1

Viskase Inc., Chicago, IL.2

Excel, Dodge City, KS.3

121


DECONTAMINATION OF BEEF CARCASSESAND SUBPRIMAL CUTS

C. L. Kastner, P. B. Kenne y , R. E. Campbell,1

R. K. Prasai, L. E. Meas e , L. R. Vog t , D. H. Kropf,2 3

D.Y.C. Fung, and C. M. Garcia Zepeda

Summary

Lactic acid sprays effectively reduce themicrobial load on both carcasses and sub-primal cuts. Lactic acid decontamination ofsubprimals appears to carry through to retailcuts during display. Because ofrecontamination during fabrication, treatingsubprimals may be more effective thantreating carcasses. This information willallow us to identify the most critical controlpoints at which to employ decontaminationpractices designed to reduce the incidence ofpathogenic bacteria and extend shelf life.

(Key Words: Microbiology, Decontamina-tion, Carcass, Subprimal.)

Introduction

This report summarizes our Food SafetyConsortium results and integrates previousresearch, current industry practices, andefficacy of decontamination practices atvarious critical control points (process stepthat leads to unacceptable microbial con-tamination if not properly controlled). Wehave completed a series of integrated studiesin an attempt to identify the most critical andeffective intervention points and technologiesfor controlling microbial contamination andassuring food safety.

To maximize safety and extend shelf lifeof meat and meat products, the meat industryand the Food Safety and Inspection Service(FSIS) strive to minimize carcass contami-nation during slaughter and subsequentprocessing. However, microbial contamina-tion during slaughter cannot be avoided com-pletely.

In addition to good manufacturingpractices designed to m inimize contaminationand trimming of contamina ted areas, sprayingcarcasses with hot water and sanitizers hasbeen employed to reduce contamination.Although spraying/rinsing techniques havereduced microbial counts on carcasses, theireffect does not necessarily carry over toresultant subprimal and retail cuts, trim usedfor further processing, and meat byproducts.The efficacy of trimming contaminated areasneeds additional investigation . The industryand FSIS have worked together tosupplement traditional carcass decontamina-tion efforts with organic (lact ic or acetic) acidrinsing because of its effect iveness for carcassdecontamination.

Because industry and FSIS were evaluat-ing pre-evisceration organic acid rinsing, ourinitial studies evaluated rinsing carcasses withsanitizers at other control points. Wedecided to rinse carcasses immediately afterrail inspection and/or after spray chilling.Carcass rinsing was effective in decreasing


122

microbial counts on the c arcass, but it did notcarry through to resultant subpr imal and retailcuts, so we also rinsed subprimal cuts beforevacuum storage.

Experimental Procedures andResults and Discussion

We evaluated microbiological quality ofcarcasses as affected by sprays of water (W),200 ppm chlorine (C), and 3% lactic acid (L)applied immediately after rai l inspection andagain following 8 h spray-chill cycle in ninedifferent combinations (W+W, C+W, L+W,W+C, C+C, L+C, W+L, C+L, and L+L).Samples for microbial counts were taken justbefore and just after spray tre atments that fol-lowed rail inspection, spray chilling, and 3days of aging. Six subprimals from eachtreated carcass were assigned randomly tothe following treatments: 1) vacuum pack-aged (VP); 2) sprayed with C and VP(C+VP); 3) VP and microwaved (VP+MW);4) inoculated with pathogens (Listeria mono-cytogenes, Salmonella enteritidis, Esche-richia coli 0157:H7, and Yersinia enter-colitica) and VP (P+VP); 5) P+C+VP; and6) P+VP+MW). All products were stored at34EF and sampled for aerobic plate counts(APCs) and/or pathogen at 4, 10, 15, 20, 30,60, 90, and 120 days of vacuum storage.

All treatment combinations involvingeither chlorine or lactic acid reduced carcasscontamination. The decrease in mean log10

APCs ranged from 0.4 to 1.8. A 1 logdecrease is a 90% reduction, and a 2 logdecrease equals a 99% reduction. The L+Ltreatment combination showed the greatestreduction. Also, most treatment combina-tions involving lactic acid tended to decon-taminate better than those without acid(Figure 1). However, carcass decontami-nation did not carry over to subprimal cuts(Figure 2). Additionally, treating subprimalcuts did not effectively reduce APCs duringextended storage (Figure 3). Maximumgrowth (6.0-7.0 log colony forming units,10

CFUs/cm ) was reached at 60 days and did2

not change during the remainder of storage.

Following pathogen inoculation , Salmo-nella did not grow; Listeria increasedgradually from 10 to 60 days, then declinedfrom 60 to 120 days. Yersinia and Esche-richia counts were not affected consistentlyby treatment.

Treating subprimal cuts wit h chlorine wasnot effective. Because lactic acid waseffective on carcasses, we tested it onsubprimal cuts and evalua ted the carryover toretail cuts during display. That studyinvolved spraying 1.5% lactic acid solution(v/v) on beef strip loins A) immediatelybefore vacuum packaging, B) immediatelyafter opening the vacuum bag at the end ofstorage, C) before vacuum packaging andagain at the end of storage, and D) beforevacuum packaging, with a water rinse at theend of storage. Loins w ere evaluated at onceor stored for 14, 28, 56, 84, or 126 days.Two different storage temperatures (30 and36EF) were used. Microbiological analyses(total aerobic plate count and presence or ab-sence of Salmonella and Listeria) wereconducted, and the overall appearance ofstrip loins was evaluated after the specifiedstorage times.

We found:

1) Acid-treated loins had lower countsthan nonacid-treated loins.

2) Spraying loins with lactic acid priorto vacuum packaging was moreeffective than spraying with acid atthe end of storage.

3) Storage at 30EF was more effectivethan storage at 36EF.

4) Proper temperature control was atleast as effective as acid treatment.

Retail cuts from the subprimals were alsoevaluated. Upon removal of the subprimalsfrom storage, 1 inch-thick steaks were cutfrom each loin. They were packaged in oxy-gen-permeable polyvinylchloride film andevaluated immediately and after display at 36± 3EF under 100 foot candles of Warm WhiteDeluxe fluorescent lighting for 3 or 5 days.


Lactic acid applied to strip loins both pre-and poststorage, and lactic acid appliedprestorage with water sprays after 84 days ofstorage at 30°F yielded up to 2 log (99%)reductions in APCs of steaks not displayed ordisplayed for 3 days and >l.0 log (90%)reductions at 5 days of display. Lactic acidtreatment pre- and post- 30°F-storageincreased the length of the lag phase ofmicrobial growth, thus increasing display life.Lactic acid was most effective at the colder(30 vs. 36°F) storage temperature . L .monocytogenes and Salmonella spp. wereabsent from all steaks.

On the basis of color, subprimal storageand/or display life were slightly shorter forlactic acid treated cuts than for controls.However, on the basis of bacterial counts,lactic acid sprays applied to strip loinsresulted in longer storage life and/or

steak display life. Preliminary data indicatesimilar results for companion vacuum-packaged retail cuts that were displayed forup to 14 d. However, the magnitude of themicrobial reduction from acid treatment ofthe subprimal was less.

Lactic acid treatment of subprimal cutsappears to carry through to retail cuts duringdisplay and is more effective than treatingcarcasses, especially when retail cuts arepackaged in oxygen-permeable film. Goodtemperature control enhanced the carryovereffectiveness of lactic acid treatment at thesubprimal level.

Details of the preceding studies are pre-sented in the next two reports.

Figure 1. Effect of Water (W), Chlorine (C), and Lactic Acid (L), either Alone or inCombination, on Mean Carcass Aerobic Plate Counts. Means of before andafter Treatment Groups with Same Letter Are Not Different (P>. 05).

1 2 3


Figure 2. Aerobic Plate Counts of Subprimal Cuts as Affected by Length of Storageand Carcass Treatment (W=Water, C=Chlorine, and L=Lactic Acid).

Figure 3. Aerobic Plate Counts of Subprimal Cuts as Affected by Length of Storageand Subprimal Treatment (VP=Vacuum Packaged, C=200 ppm ChlorineSpray, MW=Microwaved, and P=Pathogen Added).

124




125


EFFECT OF LACTIC ACID SPRAYS ONSHELF LIFE AND MICROBIOLOGICAL SAFETY

OF BEEF SUBPRIMALS

R. K. Prasai, L. E. Meas e , L. R. Vog t ,1 2

D. H. Kropf, D.Y.C. Fung, and C. L. Kastner

Summary

Beef loins were sprayed with 1.5% lacticacid either before or after vacuum storage,both before and after vacuum storage, andbefore vacuum packaging followed by awater spray after storage. We stored treatedloins at either 30EF or 36EF for up to 126days in vacuum packages. Nonsprayed ornonstored loins served as controls. Totalaerobic plate counts (APCs) and tests forpresence/absence of two importa n t foodbornepathogens, Salmonella spp. and Listeriamonocytogenes, were conducted duringstorage. Acid spraying prior to vacuumpackaging was more effective in reducingbacterial contamination than spraying afterstorage. However, counts were reduced(P<.05) for only 28 days of storage. Mostloins stored at 30EF had lower APCs thanthose stored at 36EF. Salmonella was notdetected in any samples. Twenty-eightpercent of nonacid treated and 4 percent ofacid-treated loins were positive fo r Listeriaspp. with L. monocytogenes found from onenonacid-treated loin. No change in visualcolor was observed in acid-treated loins.Appropriate timing of acid s praying in combi-nation with lower storage temperature canimprove the keeping quality and microbialsafety of meat.

(Key Words: Lactic Acid, Beef, Bacteria,Safety.)

Introduction

Initial numbers and types of microor-ganisms and storage temperature are majorfactors determining the s helf life and safety ofmeat. According to USDA, the annual costof foodborne illness in the U.S ranges from$5.2 to $6.1 billion with $3.9 to $4.3 billionattributable to meat and poultry products.Organic (lactic and acetic) acid sprayseffectively reduce microbial contamination ofcarcasses but have little or no effect inimproving the microbiological quality ofresultant fabricated cuts. Secondary con-tamination can occur during fabrication andmask effects of lactic acid decontamination.This study determined if the microbiologicalquality of meat can be improved by sprayinglactic acid directly on subprimal cuts ratherthan on carcasses.


A total of 36 strip loins in each of threereplicates were taken from a commercialprocessing line. Each loin re ceived two treat-ments, one for each half loin strip. Eachreplicate was treated as follows: I). Twelveloins were vacuum packaged and stored at30EF (6 loins) or 36EF (6 loins) for 14, 28,56, 84, or 126 days or not stored (0 days).On each specified day, a 1.5% lactic acidsolution (approx. 725 ml per loin) wassprayed on one half of each loin as a secondtreatment. II). Another group of 12 loinswas sprayed with acid solution prior tovacuum packaging followed by storage and a


126

second treatment with acid in the samemanner as described in I. III). The lastgroup of 12 loins was treated the same wayas in II, except that the second treatmentapplied to the other half of each loin waswater spray instead of acid. These threetreatment groups yielded these differenttreatment combinations: vacuum packagedcontrol (C), acid trea tment only after vacuumstorage (0-A), acid treatment before vacuumstorage (A-0), acid treatme nt before and aftervacuum storage (A-A), and acid treatmentbefore storage and sprayed with water afterstorage (A-W).

On prespecified days of storage (0, 14,28, 56, 84, and 126 days), one strip loin fromeach treatment group and storage tempera-ture was selected randomly and one half ofthat loin was cored (surface) for microbio-logical analysis. The other half of the loin re-ceived a second treatment (either acid, orwater spray) and was then sampled.

Microbiological samples obtained fromtwo halves of each loin were analyzedseparately for total aerobic plate count (APC)and for the presence or absence o f Salmo-nella spp. and Listeria monocytogene s.

Results and Discussions

Mean (log /cm ) APCs of subprimals as102

affected by treatments, storage temperatures,and length of storage are summarized in Ta-ble 1. Acid spray on loins prior to vacuumpackaging (A-0) reduced bac-

terial contamination with counts being lowerthan those of controls (C) for all storageperiods. The average reductions in meanlog APCs ranged from .4 to 1.9 (1 log10

equals 90% reduction, 2 log equals 99%reduction), with the initial mean log APC in10

control loins ranging from 3.1 to 7.3.

Microbial reduction by acid spraygenerally was successful for loins stored forup to 28 days. After 28 days, few differencesoccurred between any of the treatments andcontrols. Loins treated with acid afterstorage (0-A) had microbial counts mostsimilar to those of controls, indicating thatacid application after storage was less usefulthan acid applied before storage. Generally,the mean reduction in APC of AW or A-Aloins was slightly greater than that of A-0loins.

Although not significant (P>.05), almostall loins stored at 30EF had numerically lowercounts than those stored at 3 6EF, indicatingthe role of storage temperature as a majorhurdle to control outgrowth of microorgan-isms. Salmonella was not detected in anysamples. Twenty-eight percent of nonacid-treated and 4 percent of acid-treated loinswere positive for Listeria spp., with L.monocytogenes found from one non-acidtreated loin. We saw no change in visualcolor with acid treatment.

Appropriate time of application of acid atthe subprimal level in combination with lowertemperature of storage can improve thesafety and shelf life of meat.


127

Table 1. Mean Aerobic Plate Counts (lo g /cm ) of Control and Acid-Treateda 210

Beef Subprimals Stored in Vacuum Packages at 30 and 3 6EEF for up to26 Days

SamplingTime(days)

StorageTemp.(EF)

Treatmentsb

C 0-A A-0 A-W A-0 A-A

0 30 3.12c 2.07 2.50c 2.02c 1.92 2.36c

36 3.09c 2.80c 2.16c 1.89 2.42c 2.20c

14 30 3.46c 3.40c 2.50c 2.26 2.23 2.16

36 4.30c 4.16c 3.26c 2.26 2.35 2.10

28 30 4.20c 4.26c 2.36 2.83c 2.26 1.96

36 4.76c 5.41c 3.06 2.34 3.50 3.66c

56 30 5.10c 5.60c 4.80c 5.13c 4.35c 4.83c

36 6.16c 5.29 5.63c 5.42c 5.92c 5.89c

84 30 6.16c 6.22c 4.94c 4.56 5.48c 4.95

36 7.25c 6.66c 6.77c 5.90 6.39c 5.65

126 30 6.59c 5.98c 5.69c 5.50c 5.72c 5.48c

36 7.20c 7.08c 6.56c 6.22c 7.16c 6.65c

Individual means in each treatment are based on three samples from three loin halves in threea

replicate experiments. Each sample was taken from four different locations (two per side) ofa loin half and then combined.C = no treatment (Control); 0-A = acid sprayed after vacuum storage; A-0 = acid sprayedb

before vacuum packaging; A-W = acid sprayed before vacuum packaging followed by waterspray after storage; A-A = acid sprayed before and after vacuum storage. Means within a row with same superscript as C are not different (P>.05) from control. c



Div. of Anim. and Veterinary Sci., West Virginia University, Morgantown, WV.2


128


POLYVINYLCHLORIDE-PACKAGED LOIN STRIPSTEAKS FROM VACUUM-PACKAGED BEEF STRIP LOINS

DECONTAMINATED WITH LACTIC ACID ANDSTORED FOR UP TO 126 DAYS

L. E. Mease , D. H. Kropf, R. K. Prasai,1

P. B. Kenney , L. R. Vog t , D.Y.C. Fung,2 3

and C. L. Kastner

Summary

Aerobic plate counts (APCs), pres-ence/absence of Listeria monocytogenes andSalmonella spp., and visual color evaluationswere used to determine the microbiologicaland display quality of steaks fabricated frombeef strip loins sprayed with lactic acid (1.5%v/v) or water before, after, o r both before andafter vacuum storage (14, 28, 56, 84, or 126days) at either 30E or 36EF compared tononsprayed or nonstored controls. Lacticacid applied pre- and poststorage (126 days)at 30EF reduced APCs of steak s up to 2 log(99%). L. monocytogenes and Salmonellaspp. were absent from all steaks. Lactic acidcaused slightly more rapid colordeterioration, resulting in slightly shorterdisplay-life for steaks.

(Key Words: Decontamination, Lactic Acid,Beef Steaks, Display, Color, Bacteria.)

Introduction

Contamination of beef during slaughterand processing is inevitable. In addition toaffecting food safety, high numbers ofbacteria can degrade sensory qualities ofretail beef. Organic acids, such as lactic andacetic acids, reduce microbial loads whensprayed on carcasses. However, microbialreductions from spraying acid on carcassesdo not carry through to fabricated subprimal

cuts. Therefore, treatment of subprimals maybe more effective than treating carcasses.

The objectives of this study were todetermine the effects of lactic acid or watersprays applied to vacuum-stored beef striploins at different points d uring processing andeffects of temperature of strip loin storage onmicrobiological and display quality of retailsteaks.


A total of 36 strip loins in each of threereplicates were taken from a commercialprocessing line. Each loin had two treat-ments, one for each half loin strip. Eachreplicate was treated as follows: I). Twelveloins were vacuum packaged and stored at30EF (6 loins) or 36EF (6 loins) for 14, 28,56, 84, or 126 days or not stored (0 days).On each specified day, a 1.5% lactic acidsolution (approx. 725 ml per loin) wassprayed on one half of each loin as a secondtreatment. II). Another group of 12 loinswas sprayed with acid solution prior tovacuum packaging followed by storage and asecond treatment with acid in the samemanner as described in I. III). The lastgroup of 12 loins was treated the same wayas in II except that the second treatmentapplied to the other half of each loin wassprayed with water instead of acid. Thesethree treatment groups yielded these differenttreatment combinations: vacuum packagedcontrol (C), acid trea tment only after vacuum


129

storage (0-A), acid treatment before vacuumstorage (A-0), acid treatme nt before and aftervacuum storage (A-A), and acid treatmentbefore storage and sprayed with water afterstorage (A-W).

An 8.5 liter hand-held sprayer was usedto apply lactic acid (1.5% v/v, pH 2.4) andwater sprays at a rate of 725 m l /min for 1 min(30 sec per side).

Strip loins were vacuum packaged in B-620 oxygen-barrier shrink bags (oxygentransmission rate 30-50 ml/m /24 h/atm at2

73EF; water vapor transmission rate . 5 to .6g/100 in /24 hr in 100% relative humidity at2

100EF) using a Cryovac 8300 seriespackaging machine at the processor location.

On the specified day of storage (0, 14,28, 56, 84, or 126 days), a strip loin fromeach treatment pair was selected randomlyfrom each storage-temperature treatment andprocessed in a refrigerated (48±2EF)fabrication room. The vacuum bag wasopened with a sterile scalpel, and the striploin was "faced" by removing a steak ofsufficient thickness. Strip loins and steakswere handled aseptically.

The three steaks fabricated, 1 in. thickfrom each loin half, were assigned to one ofthree retail display periods (0, 3, and 5 days).Steaks were placed individually on anabsorbent pad in a styrofoam tray andoverwrapped with polyvinylchloride (PVC)film (high oxygen permeability) as used inretail meat counters. Steaks were displayedin open-top retail cases at 36EF under contin-uous 100-foot candle Warm White Deluxefluorescent lighting.

On the specified day, steaks were sam-pled for microbiological analysis. Aerobicplate counts (APCs) were obtained by pourplate and/or spiral plate methods from twocores per steak. A modified USDA-FSISprocedure for isolation and identification ofListeria monocytogenes was followed. Wealso tested for the presence o f Salmonella.

Color measurements and evaluationswere conducted only on the loin eye muscleof steaks assigned to 5-day retail display. Ondays 0 (before exposure to light), 3, and 5 ofdisplay, a seven-member experienced panelvisually scored "average" and "worst point"color to .5 point increments on a 5-pointscale.


Data from day 3 of display are reportedand best show the results. Microbial APCswere influenced by storage tim e, temperature,and their interaction. The lower temperature(30EF) resulted in lower counts, especiallyfor steaks from cuts vacuum-stored for 28days and longer, because of a n extended laggrowth phase through 28 days of storage.Storage for 56 days resulted in highernumbers of microbes than for 28 days (Figure1).

Treatment also affected APCs, especiallyat 28 days for steaks from loins treated withlactic acid before vacuum packaging.Microbial reductions of 2 logs (99%) wereshown for the most effective treatments. Nomicrobial counts for steaks displayed for 3days were unreasonably high. N o Listeriamonocytogenes or Salmonella were detectedon steaks, even after 5 dats of display.

Average color score was affected pri-marily by storage time (Figure 2), becausesteaks from longer stored subprimal cutswere more discolored (higher sco re). A colorscore of 3.5 or higher is considered mar-ginally unacceptable. At the higher storagetemperature, the average color score fortreatments exceeded this point after storagefor 126 days. After vacuum storage for 14and 28 days, steaks from loins treated withlactic acid were slightly darker in appearance.Instrumental color readings confirmed visualevaluations.


Figure 1. Aerobic Plate Counts of PVC-Packaged Steaks at 3 Days. of Retail Display.

Figure 2. Average Visual Color Score a of PVC-Packaged Steaks at 3 Days of RetailDisplay. a1=Bright Red, 2=Dull Red, 3=Slightl y Dark Red or Brown, 4=DarkRed or Brown, and 5=Very Dark Red or Brown.

1 3 0


131


USE OF OXYRASE® ENZYME TO ENHANCE RECOVERYOF ESCHERICHIA COLI O157:H7 FROM CULTURE

MEDIA AND GROUND BEEF

R. K. Phebus, H. Thippareddi, K. Kone,D.Y.C. Fung, and C. L. Kastner

Summary

Escherichia coli O157:H7 is a bacteriumthat has caused great concern in the meat andfood industry during the last few yearsbecause of several, well-publicized, diseaseoutbreaks, including the incident at the Jack-in-the-Box fast food chain in Seattle, Wash-ington. The organism can cause severesickness and even death in certain populationgroups. To better assure meat safety, federalmeat inspection is focusing on developingrapid methods to detect this disease agentand others. Oxyrase is a commercially avail-able enzyme that can accelera te the growth ofsome bacteria. Current techniques forisolation and culturing of E. coli O157:H7from foods require an enrichment period of18 to 24 hours, thus limiting their usefulnessfor perishable foods that are marketed quick-ly. Our investigation found that Oxyraseshortened required enrichment periods inbroth culture only. The enzyme was lesseffective in sterilized ground beef.

(Key Words: Escherichia coli O157:H7,Oxyrase, Ground Beef, Rapid Methodology,Meat Safety.)

Introduction

The January 1993 food poisoning out-break in the northwestern United Statesresulting from eating undercooked groundbeef contaminated with Escherichia coliO157:H7 has focused attention on the needfor rapid methods for detecting meat-bornehuman pathogens. The Food Safety andInspection Service of the Department ofAgriculture is examining procedures torapidly identify fresh meat and meat products

harboring pathogenic (disease-causing)microorganisms. A scientifically basedinspection system utilizing microbial testingto support current visual inspection is likelyto result. Such a system will mandateimproving existing microbiological proce-dures and developing better ones for detec-tion of various food-borne pathogens. Thesetests need to be rapid, economical, sensitive,accurate, and simple.

Escherichia coli O157:H7 was identifiedas a human pathogen in 1982. Several food-related illness outbreaks have been attributedto this microorganism over the last decade.Many have been linked to consumption ofunder-cooked contaminated ground beef.Symptoms of infection include hemorrhagiccolitis (bloody diarrhea) and hemolyticuremic syndrome (severe kidney failure);these manifestations often lead to lifelongdisability or death. A limited number ofsurveys have indicated that about 4% offresh, retail, ground beef is c ontaminated withE. coli O157:H7. However, because theorganism is difficult to recover from foods,the incidence may be higher. Severalscreening methods for the isolation and/orenumeration of E. coli O157:H7 have beendeveloped. Most are too complex and time-consuming to be useful in meat inspection.E. coli O157:H7 is usually present in foods inlow numbers and is accomp anied by competi-tive microbial populations, including othe r E.coli strains requiring differentiation. Thesefactors mandate selective enrichment proce-dures that allow E. coli O157:H7 cells torepair injuries and grow to high enough num-bers for detection, normally extending testingtimes by 18 to 24 hours. Techniques toreduce the time for enrichment, during which


132

very low numbers of E. coli O157:H7 are in-creased to detectable levels, are needed inregulatory detection of this pathogen.

Oxyrase enzyme derived from rup tured E.coli cells speeds up growth of severalbacterial groups by removing oxygen fromthe growth medium. Several studies atKansas State University have demonstratedthat Oxyrase increases growth rates of certainbacteria, especially those found in thedigestive tract of animals (i.e. , E. coli,Salmonella, and Campylobacter). Weundertook this study to evaluate incorporat-ing Oxyrase into an enrichment mediumdesigned to speed up the recovery of lowlevels of E. coli O157:H7 from culture mediaand sterile ground beef.


We worked with four strains o f E. coli,both O157 and non-O157 serotypes, isolatedfrom meats or humans. Brain Heart Infusion(BHI) broth was used as an enrichmentmedium for all experiments. After specifiedenrichment periods, McConkey Sorbitol Agar(MSA) was used as a selective platingmedium to isolate and coun t E. coli strains.In Experiment 1, flasks containing BHI brothwith (oxy +) or without (oxy –) 0.1 unit/ml ofOxyrase were inoculated with approximately1 E. coli/ml of broth. After inoculation, flaskswere incubated in a 37EC water bath andsampled hourly from 0 to 10 h and after 12,14 and 24 h by plating on MSA. Differencesin E. coli growth rates in oxy + and oxy –BHI broth were determined. In Experiment2, 10 sterile ground beef samples were pre-pared and placed into sterile plastic bags.BHI broth was

added, and samples were mixe d for 2 min ina lab blender. Oxyrase (0.1 unit/ml) wasadded to five of the samples (oxy +). One E.coli O157:H7 strain (B) and one non-O157strain (D) were investigat ed; strain B at initiallevels of 1, 10 and 100 cells/g and strain D at10 cells/g of meat. Samples were incubatedin bags at 37EC, and E. coli countsperformed hourly from 0 to 12 h and at 14,16, 18, and 24 h.


Oxyrase increased the g rowth rate for allthree pathogenic E. coli strains tested in BHIbroth, when they were initially present at <1cell/ml. However, we noticed some variationin the way different strains responded toOxyrase supplementat ion. Where differenceswere noted, they resulted from a shorteningof the lag phase (initial stage of growth) ofthe organisms. However, withnonpathogenic strain D, Oxyrase suppressedgrowth during the initial 4 h (Figure 1).Strain D numbers increased rapidly i n oxy -broth during this period. This suppressiveeffect was overcome by the samplin g at 5 h.This observation might be important indeveloping methods to specifically detectpathogenic strains o f E. coli.

When pathogenic E. coli strain B wasinoculated into sterilized meat, no enhance-ment in growth of the organism occurred.The level of Oxyrase may need to be greaterthan the 0.1 unit/ml we used, because ofpossible inhibitory effects of meat on the en-zyme. Secondly, autoclaving ground beef toachieve sterility may reduce dissolved oxygenin the samples enough to nullify the benefitsof Oxyrase. The use of co oked meat mediumfor cultivating anaerobic bacteria supportsthis hypothesis.


Figure 1. Effect of OxyraseTM on the Growth of E. coli Strains Inoculated at 1 CFU/mLinto BHI Broth at 37°C

1 3 3


Cattlemen’s Day 1994

BREED EFFECTS AND RETAINED HETEROSIS FORGROWTH, CARCASS, AND MEAT TRAITS INADVANCED GENERATIONS OF COMPOSITE

POPULATIONS OF BEEF CATTLE 1

M. E. Dikeman K. E. Gregory2,L. V. Cundiff2, R. M. Koch 3

,

and M. Koohmaraie

Summary

Retained heterosis for growth, carcass,and meat traits was estimated in F3 genera-tion steer progeny in three composite popu-lations finished on two levels of dietaryenergy density (2.82 MCal ME and 3.07MCal ME, and 11.5 % CP) and seriallyslaughtered at four endpoints at intervals of20 to 22 days. Breed effects were evaluat-ed in the nine parental breeds of Red Poll(RP), Hereford (H), Angus (A), Limousin(L), Braunvieh (B), Pinzgauer (P),Gelbvieh (G) , Simmental (S), andCharolais (C) that contributed to the three‘composite’ populations. MARC-I was l/4B, l/4 C, l/4 L, l/8 H, and l/8 A;MARC-II was l/4 G, l/4 S, l/4 H, andl/4 A; and MARC-III was l/4 RP, l/4 P,l/4 H, and l/4 A.

Breed effects were important for growthtraits; carcass traits; and retail product, fattrim and bone percentages, and weights.Even though mean slaughter weight was126.6 lb heavier for Simmental, Gelbviehand Charolais breeds, they did not differfrom Limousins in retail product weightbecause of their lower dressing percent-ages, higher fat trim percentages, and high-er bone percentages.The effects of dietary

energy density were important for mosttraits, and little interaction occurred be-tween breed group and dietary energydensity. The MARC-III composite hadlighter final and carcass weights, a lowerpercentage of retail product, a higher per-centage of fat trim, and a higher percentageof ribeye fat than the MARC-I composite,with the MARC-II composite being gen-erally intermediate. Retained heterosisgenerally was significant for each com-posite population and for the mean of thethree composite populations for weight ofretail product, fat trim, and bone.Forpercentage of retail product and fat trim,MARC-II and MARC-III composites had alower percentage of retail product and ahigher percentage of fat trim than the meanof the contributing breeds. Compositepopulations or breeds provide an opportuni-ty to use breed differences to achieve andmaintain optimum additive genetic compo-sition for carcass composition traits and touse heterosis to increase lean tissue growthrate and(or) to increase rate of fat deposi-tion.

Introduction

Fluctuation in breed composition be-tween generations in rotational crossbreed-

1This article was derived from a research paper accepted for publication in the Journal ofAnimal Science. These data are from the Germ Plasm Utilization project that was conductedunder the leadership of Dr. Keith E. Gregory at the Roman L. Hruska U.S. Meat AnimalResearch Center, Clay Center, NE. Michael E. Dikeman is a collaborator on the carcass retailproduct data collection.

2USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE.3Professor Emeritus of Animal Science, University of Nebraska, Lincoln.

134


ing systems can result in considerablevariation among both cows and calves inlevel of performance for major bio-economic traits, unless breeds used in therotation are similar in performance. Usingbreeds with similar performance charac-teristics restricts the use of breed differenc-es to meet requirements for specific pro-duction and marketing situations. Thisreport focuses on breed differences ingrowth, carcass, and meat traits and thepotential of ‘composite’ breeds as alter-natives to crossbreeds for using heterosisand genetic differences among breeds toachieve and maintain a more optimumadditive genetic (breed) composition.


Matings were made to establish threecomposite populations: MARC-I (l/4Braunvieh, l/4 Charolais, l/4 Limousin,l/8 Hereford, and l/8 Angus); MARC-II(l/4 Gelbvieh, l/4 Simmental, l/4 Here-ford, and l/4 Angus); and MARC-III (l/4Red Poll, l/4 Pinzgauer, l/4 Hereford, andl/4 Angus). F1 is defined as the firstgeneration that reflects the final breedcomposition of a composite population; Fl,F2, and F3 generations were mated amongthemselves to produce, respectively, F2,F3, and F4 generation progeny. Compositepopulations were formed from the samesires and dams represented in the ninecontributing parental breeds (Table 1).

The 1,661 steers included in this studywere unselected male progeny of 21 RedPoll, 22 Hereford, 23 Angus, 24 Limousin,26 Braunvieh, 27 Pinzgauer, 27 Gelbvieh,19 Simmental, 25 Charolais, 39 MARC-I,30 MARC-II, and 24 MARC-III sires.Calves were born in 1988, 1989, 1990, and1991. Mean birth date was April 13.Because of drought in 1988, calves wereweaned at an average age of 127 days vs.about 150 days for other years. Weanedcalves were started on a diet of 2.65 MCalME/kg of dry matter and 15.4 % crudeprotein, which was changed gradually to abackgrounding diet that was 2.69 MCalME/kg of dry matter and 12.88% crude

protein. At an average age of 203 daysover the 4 years, animals of each breedgroup were weighed and randomly assignedto treatment, stratified by weight. Prior toassigning animals to treatment, seven tonine males in each breed group were iden-tified as candidate replacement sires torepresent a broad pedigree base. Theywere near the mean weights of their respec-tive breed groups. All except candidatereplacement sires were castrated.Twofinishing diets were fed to each year-breed-group-subclass. Both were 11.5% crudeprotein. One diet had 2.82 MCal ME/kgof dry matter, and the other, 3.07.

Animals were slaughtered serially atfour end points with 20 to 22 days betweenslaughter dates, beginning at about 13 l/2mo of age. Final weights were takenwithout shrink. Carcass USDA yield andquality grade data were obtained, and oneside of each carcass was fabricated intoboneless retail cuts to .30 inch fat cover.Retail cuts then were trimmed free ofsurface fat and reweighed. Rib steaks fromeach carcass were cooked and sheared witha Warner-Bratzler shear device and evaluat-ed by a trained sensory panel.


The earlier maturing breed groups (i.e.,Angus, Hereford, Red Poll and MARC-III)had more fat than the later maturing breedgroups (i.e., Charolais, Simmental,Braunvieh, Gelbvieh, Limousin, andMARC-I). Contrary to expectations, breedgroups responded similarly to the twodietary energy densities. Further, fewbreed differences occurred in the 63-dayspan between slaughter groups 1 and 4(data not shown).

Large differences were observed amongbreed groups in growth and slaughter traits(Table 1). For initial weight, Herefordswere lightest. Gelbviehs, Pinzgauers,Simmentals and Braunviehs were heaviestand did not differ from each other.Charolais were heavier than Angus, RedPolls, and Limousins, which were interme-

135


diate in initial weight. For final weight,Herefords, Angus, Red Polls, andLimousins did not differ statistically.Simmentals, Charolais, Gelbviehs, andBraunviehs were heaviest and similar,whereas Pinzgauers differed only fromSimmentals among the heavier breedgroups. For ADG, Red Polls gained slow-est but were not different from Angus,Limousins, and Pinzgauers, whereasSimmentals and Charolais gained fasterthan all breed groups. For carcass weight,Herefords, Red Polls and Angus did notdiffer. Simmentals, Charolais, Gelbviehs,and Braunviehs were heaviest and did notdiffer from each other. Pinzgauers andLimousins were intermediate. Limousinsdressed significantly higher than all breedgroups; Angus and Charolais were interme-diate. Differences in dressing percentageamong other breed groups were relativelysmall, even though some of them weresignificant.

Adjusted fat thickness at the 12th ribranged from .14 inches in Gelbviehs to .46inches in Angus (Table 2). Breeds rankedsimilarly in ribeye area (REA) as for car-cass weight, except that Limousins hadlarger REA than all breed groups exceptBraunviehs and Gelbviehs. Differencesamong breed groups in estimated kidney,pelvic, heart fat (KPH) percentages gener-ally were small, except that Red Polls hada significantly higher KPH percentage thanall other breed groups. For marblingscore, Limousins were lower than allbreeds except Gelbviehs. Angus werehigher than all breeds except Red Polls,Herefords, and Pinzgauers. Braunviehs,Simmentals, and Charolais were intermedi-ate in marbling score and not significantlydifferent from each other.

The MARC-III composite had lighterinitial, final, and carcass weights; lowerADG; higher fat thickness; and highermarbling score than MARC-I. TheMARC-II composite had a higher fat thick-ness and marbling score than MARC-I.

Differences among breed groups inretail product, fat trim, and bone percent-ages when retail product was trimmed to .3in. fat and then to 0 in. fat are presented inTable 3. The mean differences between .3in. and 0 in. fat trim were 4.9% for retailproduct, 3.6% for fat trim, and 1.2% forbone. Differences in retail product per-centage between the two trim levels tendedto be less in breeds with less fat (i.e.,Limousins, 4.2 %) than in breeds with morefat (Herefords, 5.9%), likely becausebreeds like Limousin had less than .3 in.fat cover on some cuts, so less fat wasremoved by trimming to 0 in. Limousinshad the highest retail product percentageand lowest fat trim percentage (except forGelbviehs) and were similar to Angus andHerefords in bone percentage. Herefords,Angus, and Red Polls were similar in retailproduct, fat trim, and bone percentages.The range in fat trim percentage was12.1% among breeds at 0 in fat trim,whereas the range in bone percentage wasonly 2.4 %. The MARC-I composites hada higher percentage of retail product and alower percentage of fat trim than MARC-IIand MARC-III composites.

Differences among parental breeds inretail product and fat trim weights whenretail product was trimmed to both .3 in.and 0 in. fat are presented in Table 4.Retail product weights reflect differencesamong parental breeds in lean tissuegrowth rate. The similarity of Limousin,Simmental, Charolais, and Gelbvieh inretail product weight at 0 in. fat trim is ofinterest. Even though the mean slaughterweight for the Simmental, Gelbvieh, andCharolais breeds was 126.6 lb greater thanthat for the Limousin breed, their lowerdressing percent, lower retail productpercent, and higher bone percent resultedin no difference among these four breeds inretail product weight. The Herefords hadthe lowest retail product weight of all breedgroups, followed by Angus and Red Polls,which did not differ from each other.

136


Longissimus steaks from Angus andPinzgauers had lower Warner-Bratzlershear force values (more tender) than thosefrom all other breed groups except RedPolls (Table 5). Steaks from Gelbviehsand Limousins had higher shear forcevalues than those from all breed groupsexcept Simmental. The three compositebreed groups were not different in shearforce values. Limousins and Gelbviehs hada lower percentage of fat in the longissimusmuscle than other breed groups, whereasAngus, Red Polls, and Herefords had ahigher percentage of fat in the longissimusmuscle than most other breed groups.MARC-I composites had a lower percent-age of fat in the longissimus muscle thanMARC-II and MARC-III composites.

Sensory panel scores for tenderness,juiciness and flavor are presented in Table5. Longissimus steaks from Angus andPinzgauers were more tender than thosefrom all breed groups. Steaks fromGelbviehs were scored less tender thanthose from all breed groups exceptLimousins and Simmentals. Ranking ofbreed groups for greater sensory paneltenderness agreed very closely with theranking of breed groups for lower shearforce values. Differences among breedgroups for sensory panel juiciness weresmaller than those for tenderness. Steaksfrom Angus were scored juicier than thosefrom most breed groups; steaks from RedPolls and Herefords were scored juicierthan those from some breed groups. Dif-ferences among breed groups for sensorypanel flavor were too small to be of practi-cal importance. Longissimus muscle per-centage of fat was poorly related to flavor.

Although not presented in tabular form,the high energy diet resulted in heavierfinal and carcass weights, higher ADG,higher dressing percentage, thicker fat,larger ribeye areas, higher KPH percentag-es, and higher marbling scores. It alsoresulted in a lower percentage of retailproduct, higher percentage of fat trim,

and lower percentage of bone. However,weight of retail product was higher forcattle on the high energy diet. The highenergy diet also resulted in more fat in thelongissimus muscle and lower shear forcevalues.

Estimates of retained heterosis forgrowth traits and for cooler-measuredcarcass traits are presented in Table 6. Fortraits related to growth and size, retainedheterosis generally was significant for eachcomposite population and for the mean ofthe three composites. Retained heterosiswas not observed for dressing percentageor adjusted fat thickness. Significant re-tained heterosis was observed for marblingscore for the MARC-II composite but notfor MARC-I or MARC-III composites orfor the mean of the three composites.

Estimates of retained heterosis for retailproduct, fat trim, and bone percentages at0 in. fat trim are presented in Table 7.For composite MARC-I, retained heterosiswas not significant for retail product or fattrim but was significant for bone. Forcomposite MARC-II, retained heterosis wassignificant for retail product (less), fat trim(greater), and bone (less) percentages. Forcomposite MARC-III, retained heterosiswas significant for retail product (less) andfat trim (greater). For the mean of thethree composites, retained heterosis wassignificant for retail product (less), fat trim(greater), and bone (less) percentages.

Estimates of retained heterosis for shearforce of the longissimus muscle and per-centage of fat are presented in Table 7. Forcomposite MARC-II, retained heterosis wassignificant (greater) for fat percentage inthe longissimus muscle. Significantlygreater shear force was required for com-posite MARC-III than for the mean of thecontributing purebreds. This anomaly isinterpreted to result from chance, becausethere is no biological basis for this observa-tion.

137


Table 1. Least Square Means for Growth and Slaughter Traits

Initial Final Carcass DressingWeight Weight ADG Weight Percent

Breed Group N (lb) (lb) (lb/d) (lb) (%)

Red Poll 114 551 1158 2.58 695 60.0Hereford 146 478 1118 2.72 675 60.3Angus 118 514 1136 2.64 697 61.3Limousin 142 531 1144 2.61 728 63.4Braunvieh 139 602 1250 2.78 748 59.7Pinzgauer 118 609 1228 2.65 730 59.5Gelbvieh 150 611 1250 2.73 750 59.9Simmental 127 604 1281 2.90 767 59.8Charolais 126 587 1263 2.90 767 60.7D.05a 24 42 . l l 27 .8MARC-I F3 178 584 1241 2.81 761 61.2MARC-II F3 148 604 1263 2.81 765 60.5MARC-III 3

D.05b155 560 1197 2.70 725 60.6

24 43 .13 28 .8aD.05 is the approximate difference between means of parental breeds required forsignificance.bD.05 is the approximate difference between means of all breed groups required forsignificance.

Table 2. Least Square Means for Cooler-Measured Carcass Traits

Adj. Fat REA Est. KPHBreed Group

Marbling(inches) (inches2) (%) Scorea

Red Poll .30 10.8 3.3 5.3Hereford .44 10.5 2.4 5.2Angus .46 10.6 2.6 5.4Limousin .17 13.4 2 . 5

.184.4

Braunvieh 13.2 2.8Pinzgauer .17 12.3 2.7

4.85.2

Gelbvieh .14 13.0 2.7 4.5Simmental .16 12.6 2.5 4.8CharolaisD.05b

.15 12.5 2.8 4.7

.05 .54 .3 .3MARC-I F3 .23 12.9 2.9 4.8MARC-II F3 .32 12.1 2.9 5.1MARC-III F3 .36 11.5 3.1 5.3D.05C .06 .56 .3 .3

a4.00-4.90 = slight; 5.00-5.90 = small.bD.05 is the approximate difference between means of parental breeds required forsignificance.cD.05 is the approximate difference between means of all breed groups required forsignificance.

138


Table 3. Least Square Means for Carcass Composition (Percentages)

Retail Producta Fat Trim Bone

.30 inchb 0 inchC .30 inchb 0 inchC .30 inchb 0 inchC

Breed Group % % (% ) (%) (%) (%)

Red Poll 67.8 62.6 18.6 22.4 13.6 14.9Hereford 20.8 25.5 13.2 14.4Angus

66.0 60.167.1 61.576.5 72.3

20.0 24.4 12.9 14.1Limousin 10.4 13.4 13.1 14.3Braunvieh 71.9 67.3 12.9 16.1 15.1 16.5Pinzgauer 71.5 66.8 13.7 17.0 14.8 16.1Gelbvieh 74.2 70.0 11.3 14.2 14.5 15.8Simmental 72.8 68.4 12.4 15.5 14.8 16.1Charolais 73.2 68.7D.05d

11.9 15.0 14.9 16.21.3 1.5

67.21.5 1.6 .4 .4

MARC I F3 71.968.3 63.1

14.4 17.9 13.7 14.9MARC II F3 18.3 22.3 13.4 14.7MARC III F3 67.2 61.9 19.2 23.3 13.5 14.8D.05e 1.4 1.5 1.5 1.7 .4 .4

aRetailchemical analysis of lean trim.

product includes steaks and roasts plus lean trim adjusted to 20% fat based onbSubcutaneous and accessible intermuscular fat trimmed to .3 inches.cAll subcutaneous and accessible intermuscular fat removed.dD.05 is the approximate difference between means of parental breeds required forsignificance.eD.05 is the approximate difference between means of all breed groups required forsignificance.

Table 4. Least Square Means for Carcass Composition (Weights)

Retail Product Fat Trim

Breed Group.30 inchb

(lb) 0 inchc.30 inchb

(lb) 0 inchC

Red Poll 446.5 412.6 124.4 149.7166.3

Angus 443.6 427.8 134.9Hereford 424.0 385.9 136.5

164.5Limousin 528.8 499.4 73.4 93.9Braunvieh 511.9Pinzgauer 496.1

478.5 94.2 117.3

Gelbvieh 529.4463.5 96.1 119.1498.8 82.9 103.9

Simmental 527.7 495.0 93.1 115.5Charglais 532.1 499.0 88.0

18.1 17.6 12.6110.9

D.05d

MARC I F3 521.3 486.4 105.614.1

131.0

MARC III F3 464.4 427.1MARC IIF3 497.4 459.1 134.9 164.1

135.6 164.1D.05e 18.7 18.3 13.0 14.6

aRetail product includes steaks and roasts plus lean trim adjusted to 20% fat based onchemical analysis of lean trim.bSubcutaneous and accessible intermuscular fat trimmed to .3 inch.cAll subcutaneous and accessible intermuscular fat removed.dD.05 is the approximate difference between means of parental breeds required forsignificance.eD.05 is the approximate difference between means of all breed groups required forsignificance.

139


Table 5. Least Square Means for Percentage of Fat,Sensory Panel Traits for the Longissimus (Ribeye) Muscle

Shear Force Values and

Breed Group % Fat Shear Force, lbaSensory Panel

Tendernessb Juicinessb Flavorb

Red PollHerefordAngusLimousinBraunviehPinzgauerGelbviehSimmentalCharolaisD.05C

MARC IIMARC IIMARC IIID.05d

4.64.54.82.83.74.23.23.73.4.5

3.64.34.6

.5

10.411.29.9

12.311.29.9

12.812.111.5

.911.011.211.2

.9

5.25.15.64.95.15.44.64.85.0.3

5.25.05.1

.3

5.35.35.45.05.15.25.05.15.1.2

5.15.25.2

.2

5.04.84.94.84.95.04.84.84.9.l

4.94.94.9.l

aShear force required to cut through a .5 inch diameter core.bScore of 8 = extremely tender, juicy and flavorful; 5 = slightly tender, juicy andflavorful; 1 = extremely tough, dry, and bland.cD.05 is the approximate difference between means of parental breeds required forsignificance.dD.05 is the approximate difference between means of all breed groups required forsignificance.

Table 6. Effects of Retained Heterosis on Growth and Slaughter Traits

Initial Final Carcass Dressing AdjWeight Weight ADG Weight Percent Fat REA Marbling

Item (lb) (lb) (lb/d) (lb) (%) (inch) (inch2) Score

Heterosis:

MARC Ia minuspurebreds 30.2** 45.9** .70* 29.5** .08 -.008 .54** -.03

MARC IIa minuspurebreds 51.2** 67.7** .060† 42.3** .13 .012 .43** .15**

MARC III a minuspurebreds 22.9** 37.0** .055† 26.2** .29 .012 .48** .04

Mean heterosis:

All compositesminus purebreds 34.84** 50.27** .062** 32.6**aF3 generation progeny.†P<.10.*P.05.**P<01.

.17 .004 .48** .05

140


Table 7. Effects of Retained Heterosis on Carcass Composition and Warner-BratzlerShear Value

Retail Producta Fat Trim Bone Retail Product Shear Longissimus0 Inchc 0 Inchc 0 InchC 0 Inchb Forceb Muscle Fat

Item % % % lb lb %

Heterosis:

MARC Id minuspurebreds -.ll .49 -.38** 18.1** -.33 -.08

MARC IIa mi-nus purebreds -1.90** 2.35** -.45** 12.6** -.26 .28*

MARC IIIa

minus purebreds -.89* 1.00* -.10 10.35* .93** .06

Mean heterosis:

All compositesminus purebreds -.97** 1.28** -.31** 13.7** .01 .09

aRetail product includes steaks and roasts plus lean trim adjusted to 20% fat based on chemicalanalysis of lean trim.bAll subcutaneous and accessible intermuscular fat removed.cShear force required to shear through a .5 inch diameter core.*P<.05.**P< .01.

141


This article was derived from a research paper accepted for publication in the Journal of1

Animal Science. These data are from the Germ Plasm Utilization project that was conductedunder the leadership of Dr. Keith E. Gregory at the USDA, ARS, Roman L. Hruska U.S.Meat Animal Research Center, Clay Center, NE. Michael E. Dikeman is a collaborator onthe carcass retail product data collection. USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE.2

Professor Emeritus of Animal Science, University of Nebraska, Lincoln.3

142


ESTIMATES OF GENETIC AND PHENOTYPICPARAMETERS FOR CARCASS AND MEAT TRAITS

OF BEEF CATTLE 1

M. E. Dikeman, K. E. Gregor y , L. V. Cundif f ,2 2

R. M. Koch , and M. Koohmaraie 3 2

Summary

Data from nine parental breeds and threecomposite populations described in thepreceding article were used to calculateheritabilities and phenotypic and genotypiccorrelations among carcass and meat traits.Phenotypic correlations indicated thatmarbling was a poor predictor of longissimusmuscle palatability attributes of the individualcarcasses. Heritability estimates wereintermediate to high for fatness measures butgenerally low for palatability attributes. Thehigh negative genetic correlation (-.56)between percentage of retail product andmarbling score and the relatively low geneticcorrelations between percentage of retailproduct and palatability attributes suggestsimultaneous selection for percentage ofretail product and palatability, rather than formarbling score. Correlations among breedgroup means were generally high betweenmeasures of fatness and palatability attributesand were high and negative betweenpercentage of retail product and marblingscore or other fatness measures. Thus,opportunity is limited to select among breedsfor high levels of marbling and a highpercentage of retail

product at the same time. The most logicalapproach to resolving that genetic antago-nism is to form composites from breeds thatcontribute an optimum balance betweenfavorable carcass composition and desirablemeat palatability.

(Key Words: Carcass, Meat Palatability,Heritabilities, Genetic Correlations.)

Introduction

Although interest in carcass and meattraits has increased dramatically in recentyears, data on genetic relationships andheritabilities of carcass traits are limited. Ourobjective in this study was to estimatephenotypic and genetic (co)variation forcarcass and meat traits of beef cattle.


Breeds and matings used to establish thethree composite populations, as well asspecifics of feeding, management, slaughter,carcass data collection, carcass fabricationand longissimus palatability traits weredescribed in the preceding article.


143


Differences among breed groups werestatistically significant for all traits analyzed.Breed group means were presented in thepreceding article.

Estimates of genetic correlations (rg's),phenotypic correlations (rp's), and heritabil-ities (h ) for carcass and meat traits are2

presented in Table 1. The heritabilityestimate for 12th rib adjusted fat thicknesswas moderate (h=.30). Twelfth rib adjusted2

fat thickness accounted for considerablevariation in percentage of retail producttrimmed free of surface fat (rp=-.56, R =.31),2

but accounted for little variation in marblingscore (rp=.24, R =.06). The heritability2

estimate for marbling was high ( h=.52).2

Variation in marbling score accounted forlittle of the variation in longissimus shearforce (R =.05) and sensory panel evaluations2

of tenderness (R =.03), juiciness (R=.04), or2 2

flavor (R =.01). These cattle were slaugh-2

tered at an average age of 437 days,following semi-accelerated fe eding. Marblinghad a very low predictive value forlongissimus palatability of individual car-casses. The relationships of longissimus fatpercentage with retail product and longissi-mus palatability were similar to those ofmarbling. The heritability estimates forlongissimus shear force (h =.12) and sensory2

panel tenderness (h =.21), juiciness (h=.24),2 2

and flavor (h =.06) were relatively low, but2

that for percent retail product was high(h =.50).2

Generally, estimates of genetic correla-tions were much higher than estimates ofphenotypic correlations. Even thoughmarbling was a poor predictor of longissimuspalatability of individual carcasses, the highrg's of marbling and longissimus fat withshear force (rg's = -1.00 and -.93,respectively) and the high rg (.96) betweenmarbling and longissimus fat suggest thatmarbling may be an indirect selectioncriterion to reduce shear force.

The relatively high negative rg of mar-bling with percentage of retail product (-.56)

reveals the high genetic antagonism betweenthese two traits. However, the rg's of retailproduct percentage with longissimus shearforce and sensory panel evaluations ofpalatability were low.

Correlations among breed group meansfor carcass and meat traits are presented inTable 2. Marbling score and percentage oflongissimus fat were highly correlated withshear force (-.80 and -.74) and with sensorypanel scores for tenderness and juiciness(range from .65 to .92). The correlation ofmarbling score with sensory panel flavor was.61. The correlation between marbling scoreand longissimus fat was .99.

These values reflect high correlationsamong breed group means for both marblingscore and percentage of lo ngissimus fat at the12th rib and palatabili ty attributes. However,high correlations also wer e observed amongbreed group means for marbling score andlongissimus fat percentage with othermeasures of fat, e.g., 12th rib adjusted fat(.81 and .82). The correlations of marblingscore and longissimus fat percentage withpercentage of retail product (free of fat) were- .94 and -.95. Retail product percentagewas generally negatively associated withpalatability attributes, suggesting limitedopportunity to select among breeds toachieve high levels of marbling simulta-neously with a high percent retail product inthe carcass

The optimum way to resolve the gener-ally high genetic antagonism between retailproduct percentage and meat palatability maybe to form composites from breeds thatcontribute an optimum balance betweenfavorable carcass composition and desirablemeat palatability. Further, desirable carcassand meat traits should be balanced withproduction traits needed to achieve highproduction efficiency in a given productionenvironment.


144

Table 1. Genetic and Phenotypic Parameters among Carcass and Meat Traits ofCattlea,b,c

TraitAdj. Fat Th.

(inch)Marbling

Score

LongissimusMuscle Fat

(%)

ShearForce(lb)

Adj. fat th. (inch) .30 ± .09 .24 .26 -.06

Marbling score .32 ± .16 .52 ± .10 .63 -.23

Longissimus muscle fat (%) .28 ± .17 .96 ± .06 .47 ± .09 -.23

Shear force (lb) -.35 ± .34 -1.00 ± .45 -.93 ± .44 .12 ± .08

Tenderness .30 ± .25 .34 ± .19 .34 ± .20 -.98 ± .74

Juiciness .45 ± .23 .28 ± .18 .41 ± .18 -.96 ± .53

Flavor .31 ± .45 .34 ± .38 .48 ± .43 -1.00 ± 1.00

Retail product (%) 0 in fat trim -.76 ± .28 -.56 ± .19 -.55 ± .20 .22 ± .26

Heritabilities (h ) on diagonal (underlined).a 2

Genetic correlations (rg's) below diagonal.b

Phenotypic correlations (rp's) above diagonal.c

Table 2. Genetic and Phenotypic Parameters among Carcass and Meat Traits ofCattlea,b,c

Sensory Panel Retail Product(%) 0 inFat TrimTrait Tenderness Juiciness Flavor

Adj. fat th. (inch) .05 .10 .10 -.56

Marbling score .19 .20 .12 -.42

Longissimus muscle fat (%) .16 .20 .12 -.47

Shear force (lb) -.57 -.19 -.23 .15

Tenderness .21 ± .08 .60 .16 -.11

Juiciness .91 ± .14 .24 ± .08 -.06 -.14

Flavor .81 ± .60 1.00 ± .86 .06 ± .08 -.14

Retail product (%) 0 inch fat trim -.14 ± .22 -.31 ± .21 .02 ± .38 .50 ± .10

Heritabilities (h ) on diagonal (underlined).a 2

Genetic correlations (rg's) below diagonal.b

Phenotypic correlations (rp's) above diagonal.c


145

The cattle Germ Plasm Utilization (GPU) research programbegan with the 1978 breeding season. The primary objectiveis to estimate the retention of combined individual and maternalheterosis in advanced generations o f 'inter se' mated 'composite'populations establishe d with contributions from either four or fiveparental breeds. This research program is the largest, mostcomprehensive one of its kind.

Additional information on retained heterosis from compositepopulations for major bioeconomic traits can be obtained bywriting to Dr. Keith E. Gregory, USDA, ARS, Roman L. HruskaU.S. Meat Animal Research Center, P.O. Box 166, Clay Center,Nebraska 68933.

Table 3. Correlation Coefficients among Breed Group Means for Carcass and Meat Traits

Trait

Shear

Force

(lb)

Sensory PanelAdj.

Fat Th.

(inch)

Marbling

score

Longissimus

Muscle Fat

(%)Tenderness Juiciness Flavor

Shear force (lb)

Sensory Panel

Tenderness -.95**

Juiciness -.82** .79**

Flavor -.86** .75** .55

Adj. fat th. (inch) -.49 .54 .82** .17

Marbling score -.80** .72** .92** .61* .81**

Longissimus muscle fat (%) -.74** .65* .92** .55 .82** .99**

Retail product .0 inch fat trim (%) .62* -.55 -.87** -.37 -.91** -.94** -.95**

*P<.05. **P<.01.


146

INDEX OF KEY WORDS

Indexer's note: The pages identified here are th e first pages of each article which uses the listedkey word.

Acidosis 23, 29Alfalfa 26, 92, 95Amino Acid 48Anestrus 111Bacteria 125, 128Beef 125Beef Cattle 86Beef Cows 89Beef Heifers 40, 101, 104, 107Beef Steaks 128Big Bluestem 98Birth Weight 116, 119Bovine Respiratory Disease 35Breeding 56Bulls 56, 113Calves 48Calving Difficulty 40Carcass 121, 142Cattle 23, 29Cattle Feedlot 64Chlortetracycline 51Chromium 31Color 128Copper 35, 45, 46Corn 70, 74, 81Cost of Production 60Cow Weight 116Cow/Calf 60Decontamination 121, 128Digestibility 67Display 128Economies of Size 60Energy Levels 104Escape Protein 13Escherichia coli O157:H7 131Estradiol 13, 16Estrous Cycles 111Expected Progeny Differences 56Feedlot 16, 20Fertility 104Finishing Cattle 26Finishing Steers 1, 7First-Service Conception 107Fly Parasites 64

Forage 43, 89Forage Quality 98Forage Sorghum 77Fourplex® 46Frequency 86Genetic Correlations 119, 142Grain Content 70Grain Processing 23Grain Sorghum 77Grazing Selectivity 43Grazing Time 53Ground Beef 131Growing Cattle 74Growing Steers 11Heat Stress 38Heifer Development 101Heritabilities 119, 142Heritability 116Hybrid 77, 81IBR 35Implants 13, 40Intake 89Ionophore 113Kansas 81Lactic Acid 125, 128Lignin 98Limit-Feeding 38Lysine 48Marketing 53Meat Palatability 142Meat Safety 131Metabolizable Protein 1Methionine 11, 48Micotil® 50Microbiology 121Monensin 113Morbidity 35Morphology 113Native Grass 43, 51Night Feeding 38Nitrogen Retention 11Nutritive Value 70Ovarian Function 104Oxyrase 131Pellets 92Performance 1, 7, 113Pest Management Costs 64Plant Part 67

Postpartum 111Prairie Hay 95Pregnancy Rates 107Profitability 60Protein 95Protein Level 13Puberty 101Ralgro® 40Range Forage 92Rapid Methodology 131Receiving Program 50Respiratory Disease 31Roughage Level 20, 23Rumen 4Rumen pH 23, 29Ruminal Degradable Protein 89Ruminal Digestion 95Safety 125Selection 56Semen 113Serum Hormones 16Shrink 53Silage 67, 70, 74, 77Sodium Bicarbonate 29Sorghum 67, 74Soybean Meal 7Stable Fly 64Steers 4, 53Stocker Calves 50Stocker Cattle 51Subacute Acidosis 26Subprimal 121Suckling 111Supplementation 92Supplements 86Synovex-C® 40Trace Mineral 43Trace Minerals 45, 46Trenbolone Acetate 13, 16Urea 1, 7Urea, Digestibility 4Utah 81Weaned Calves 31Weaning Weight 116, 119Whole Shelled Corn 20Yearling Weight 119Zinc 35, 45, 46


147

BIOLOGICAL VARIABILITY AND STATISTICAL EVALUATION OF DATA

The variability among individual animals in an experiment leads to problems ininterpreting the results. Animals on treatment X may have a higher average daily gain thanthose on treatment Y, but variability within the groups may indicate that the difference betweenX and Y is no t the result of the treatment alone. You can never be totally sure that thedifference you observe is due to the treatment, but statistical analysis lets researchers calculatethe probability that such differences are from chance rather than from the treatment.

In some articles, you will see the notation "P<.05." That means the probability that theobserved difference was due to chance is less than 5%. If two averages are said to be"significantly different," the probability is less than 5% that the difference is due to chance —the probability exceeds 95% that the difference is true and was caused by the treatment.

Some papers report correlations — measures of the relationship between traits. Therelationship may be positive (both traits tend to get larger or smaller together) or negative (asone gets larger, the other gets smaller). A perfect correlation is either +1 or –1. If there is norelationship at all, the correlation is zero.

You may see an average given as 2.5 ± .1. The 2.5 is the average; .1 is the "standarderror." That means there is a 68% probability that the "true" mean (based on an unlimitednumber of animals) will be between 2.4 and 2.6. "Standard deviation" is a measure ofvariability in a set of data. One standard deviation on each side of the mean is expected tocontain 68% of the observations.

Many animals per treatment, replicating treatments several times, and using uniformanimals all increase the probability of finding real differences when they actually exist.Statistical analysis allows more valid interpretation of the results, regardless of the number ofanimals in an experiment. In the research reported herein, statistical analyses are included toincrease the confidence you can place in the results.

In most experiments, the statistical analysis is too complex to present in the spaceavailable. Contact the authors if you need further statistical information.

WEATHER DATA, 1992-1993

On the following page are graphs of the 1992 and 1993 Manhattan weather. They wereproduced by the Kansas Agricultural Experiment Station Weather Data Library. The smoothline that starts in the lower left corner of each graph is the normal accumulated precipitationsince January 1. The rough line starting in the lower left corner represents actual accumulatedprecipitation. A long horizontal section of that line represents time during which noprecipitation fell. A vertical section represents precipitation. The other two smooth linesrepresent average daily high and low temperatures, and the rough lines represent actual highsand lows.

These graphs are included because much of the data in this publication, especially dataon animal maintenance requirements and forage yields, can be influenced by weather. Weathergraphs have been included in Cattlemen's Day publications since 1985.


Summaries of Weather in Manhattan, KS, 1992 and 1993

148


S R P 7 0 4

Agricultural Experiment Station, Kansas State University, Manhattan 66506-4008M a r c h 1 9 9 4

Kansas State University is committed to a policy of non discrimination on the basis of race, sex, national origin, disability, religion, age, sexual orientation, or other non merit reasons, inadmissions, educational programs or activities, and employment, all as required by applicable laws and regulations. Responsibility for coordination of compliance efforts and receipt of inquiries,including those concerning Title IX of the Education Amendments of 1972 and Section SO4 of the Rehabilitation Act of 1973, and the Americans with Disabilities Act, has been delegated toJane D. Rowlett, Ph.D., Director, Unclassified Affairs and University Compliance, 214 Anderson Hall, Kansas State University, Manhattan, KS 66506-0124 [913/532-4392).3M


Documents

SRP704 1994 Cattlemen's Day - K-State ASI · Factors Influencing First-Service Conception and Overall Pregnancy Rates in ... Urea is a common source of rumen degrad-able nitrogen