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CULL SOW FEEDING AND MANAGEMENT STRATEGIES 1

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Impact of Energy Intake and Pregnancy Status on Rate and Efficiency of Gain and 3

Backfat Changes of Sows Post-weaning 4

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G. C. Shurson*,1 , G. W. Libal**,2 , J. Crenshaw***, , C. R. Hamilton**,3, R. L. 6

Fisher*,4, D. D. Koehler*,5, and M. H. Whitney* 7

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*Department of Animal Science, University of Minnesota, St. Paul 55108, 9

**Department of Animal and Range Science, South Dakota State University, 10

Brookings 57007, and ***Department of Animal and Range Sciences, North Dakota 11

State University, Fargo 58105 12

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ABSTRACT: A collaborative study was conducted to evaluate factors related to 14

determining optimal feeding and management programs for increasing net returns 15

from marketing cull sows. A total of 269 multiparous sows averaging 192 kg body 16

weight were weaned, moved to individual gestation crates, and assigned to one of 17

1 To whom corrrespondence should be addressed. 2 Current address: 9101 Riverstone Ct., College Station, TX 77845. 3 Current address: Darling International, 251 O’Connor Ridge Blvd., Suite 300, Irving, TX 75038. 4 Current address: Vigortone Ag Products, Inc., 5264 Council St. NE, P.O. Box 1230, Cedar Rapids, IA 52406. 5 Current address: AgriNutrition Services, Inc., 1240 East Third Ave., Shakopee, MN 55379.

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eight treatment combinations in a 2 x 2 x 2 factorial arrangement for a 42 d post-1

weaning feeding experiment. Factors included limit (L) (1.8 kg/sow/d) or ad libitum 2

(AL) access to feed wk 1 post-weaning, corn-soybean meal (C) or barley-sunflower 3

meal (B) diet, and pregnant (P) or non-pregnant (N) status. All sows were provided 4

ad libitum access to feed from wk 2 to wk 6 post-weaning. Gain (G) and feed intake 5

(FI) data were collected weekly for each sow and used to calculate gain:feed (G/F). 6

Ultrasonic backfat (BF) data were collected on d 0, d 21, and d 42 post-weaning. 7

Sows on the AL treatment had greater FI (P < 0.05) but similar G (P = 0.80) for the 8

42 d post-weaning period compared to sows on the L treatment. Most of this 9

response was due to lower sow body weight loss during wk 1 post-weaning (P < 0.01) 10

when sows were provided AL (-7.2 kg) compared with L (-13.2 kg) access to feed. 11

Sows fed the C diet had higher G (P < 0.01), had improved G/F (P < 0.01) and 12

increased BF (P < 0.01) over the 42 d feeding period than sows fed B. The C diet 13

resulted in less sow body weight loss (P < 0.01) during wk 1 (-8.8 kg) than the B diet 14

(-11.6 kg). Pregnant sows (P) had higher G, FI, G/F and BF (P < 0.01) than N sows 15

over the 42 d feeding period. Most of this advantage occurred during wk 4 post-16

weaning when FI and G of N sows was lower (P < 0.01) than P sows. An economic 17

analysis indicated that, when cull sow prices are relatively high and feed prices 18

moderate to low, maintaining and managing cull sows for an additional 6 weeks 19

post-weaning may be economically advantageous compared to 0 or 3 weeks. P sows 20

fed the C diet produced the greatest economic return. These results suggest that 21

mating sows as they return to estrus post-weaning and providing ad libitum access 22

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to a corn-soybean meal diet improves growth performance and feed efficiency, and 1

may thereby provide increased returns when marketing cull sows. 2

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Key Words: Swine, Sows, Post-weaning, Feed Intake, Pregnancy, Energy 4

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Introduction 6

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The sale of cull sows represents a small, but significant economic contribution (4 8

to 6 %) to the swine industry. Unfortunately, little research has been conducted to 9

evaluate feeding, management and marketing strategies to improve the economic 10

value of this derivative of pork production. Previous studies have shown variable 11

performance levels of cull sows fed corn-soybean meal diets for various lengths of 12

time post-weaning. Shurson et al. (1991) showed that sow body weight and 13

condition and previous level of performance contribute to expected performance of 14

sows during a post-weaning feeding period. 15

Sows can be either sold immediately after weaning as wet sows, or fed for a 16

period of time and marketed as dry sows. Economic returns from feeding cull sows 17

prior to market are dependent on a number of different factors including feed cost, 18

rate and efficiency of weight gain, facility costs and/or availability, market price, 19

and discounts for wet sows. Evaluating feeding programs and diet composition that 20

may improve feed efficiency or weight gain may offer significant opportunities for 21

swine producers to increase economic returns by feeding cull sows prior to 22

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marketing. 1

This study was conducted to test several post-weaning feeding strategies that 2

may be implemented prior to marketing of cull sows. The objectives of this study 3

were to evaluate the impact of dietary energy density, feeding level, and pregnancy 4

status post-weaning on the rate, efficiency, and composition of weight gain in sows. 5

In addition, an economic analysis was conducted to determine which strategy or 6

combination of strategies provides the greatest net economic return, and if a 3 or 6 7

week post-weaning period provides additional return compared to marketing wet 8

sows. 9

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Materials and Methods 11

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Animals and Measurements 13

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A total of 269 multiparous sows from three different herds, Univ. of Minnesota 15

(MN), North Dakota State Univ. (ND), and South Dakota State Univ. (SD), were 16

used. Genetic composition of sows at MN and SD were Yorkshire x Landrace F1's, 17

and at ND were Yorkshire x Hampshire x Duroc females. Sows were individually 18

housed in confinement gestation facilities and fed in individual gestation stalls 19

throughout the experimental feeding period.20

Animals were weighed immediately following weaning and assigned to one of the 21

eight treatments based on weight, body condition, and parity. All sows were 22

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weighed weekly until conclusion of the 42 d study to determine growth performance. 1

Individual sow feed consumption was also measured on a weekly basis. Average 2

backfat measurements were taken on all sows using a backfat probe (Renco 3

LeanMeater) at weaning, d 21 and d 42 post-weaning in an attempt to measure 4

body composition change. Sows assigned to pregnant (P) treatments were mated as 5

they returned to estrus (3 - 7 d post-weaning) to provide comparative differences in 6

rate, efficiency, and composition of gain. Sows that were mated but returned to 7

estrus wk 4 post-weaning were removed from the trial. Those sows assigned to 8

restricted (R) feeding levels were limit fed 1.8 kg/d for the first wk post-weaning, 9

and then allowed ad libitum feeding for the remaining 5 wks of the trial. 10

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Experimental Diets and Treatments 12

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All sows were fed either a corn-soybean meal (C) or barley-sunflower meal (B) 14

based diet (Table 1) to study the effects of dietary energy density on growth rate, 15

efficiency, and composition of gain. Separate vitamin and trace mineral premixes 16

were used by each participating station, but all premixes were included to ensure 17

that vitamins and minerals were provided to exceed NRC (1988) minimum 18

recommendations. Corn-soybean meal diets were formulated to contain 3172 kcal 19

ME/kg, 12.2% crude protein, and 0.52% lysine. Sows were assigned to one of eight 20

treatments arranged in a 2 x 2 x 2 factorial of pregnancy status (pregnant (P) or 21

non-pregnant (N)), feeding level during the first week post-weaning (ad libitum 22

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(AL) or limit fed (L)), and diet composition (corn-soybean meal (C) or barley-1

sunflower meal (B)). Barley-sunflower meal diets were formulated to contain 2754 2

kcal ME/kg, 14.6% crude protein, and .52% lysine. Diets were estimated to contain 3

2.8 and 6.4 % crude fiber, respectively, and were equivalent in Ca and P content. 4

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Statistical Analysis 6

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The experiment was a 2 x 2 x 2 factorial arranged in a randomized complete 8

block design. The data were statistically analyzed using the GLM procedure of SAS 9

(1985). Individual sow measurements were considered the experimental unit. Least 10

square means were calculated and used to evaluate responses to first week feeding 11

level, diet fed (energy level), and pregnancy status for ADG, ADFI, G/F (weekly and 12

total) and change in backfat (wk 1-3, wk 4-6, and wk 1-6). Initial sow body weight 13

at weaning was used as a covariate for ADG, ADFI, and G/F responses, while initial 14

sow backfat at weaning was used as a covariate for evaluating changes in backfat 15

depth. Location (station) did not appreciably affect (P > 0.15) growth or backfat 16

responses to first week feeding level, diet, or pregnancy status, and therefore those 17

interactions were not included in the model. 18

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Economic Analysis 20

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An economic analysis was conducted utilizing growth performance and feed 22

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intake data obtained from this experiment, based on the model used by Plain and 1

Shurson (1999). Least squares means for ADG and ADFI were utilized to determine 2

body weight gain and feed intake over 3- and 6-week post-weaning periods, 3

dependent on pregnancy status, feeding level week 1 post-weaning, diet fed, and all 4

interactions between these dietary and management factors. An initial sow weaning 5

weight of 190 kg and fixed non-feed cost of $1.50/week/sow marketed were assumed. 6

A low or high ($ 0.10 and $0.15/kg) feed cost, low or high ($0.70 and $0.90/kg live 7

body weight) cull sow market price, and presence or absence of a $0.07/kg wet sow 8

market price discount were included in the model. Differences in diet cost, expense 9

for breeding, and any additional non-feed costs were not considered, since these 10

costs may be quite variable dependent on individual operation. A pregnant sow 11

discount at the time of marketing was not considered, since most procurement 12

facilities would not consider a difference at 6 weeks gestation. In addition, many 13

cull sows are marketed on a carcass yield basis, and therefore presence of conceptus 14

would be accounted for. 15

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Results and Discussion 17

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Sow Responses to Dietary Energy Density Post-Weaning 19

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Sows fed the lower energy dense barley-sunflower meal diet (B) gained an 21

average of 0.18 kg/sow/d less (P < 0.01) than sows fed the higher energy dense corn-22

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soybean meal diet (C) throughout the entire 42 d post-weaning feeding period 1

(Table 2). Except during wks 3, 4, and 6, sows fed the C diet had increased daily 2

gains throughout the trial, but especially during wk 1 (P < 0.01) and wk 5 (P < 0.05). 3

This resulted in an 18.2% increase in body weight gain and 3.8% increase in ending 4

sow wt (P < 0.05). 5

Feed intake was depressed for sows fed the lower energy diets during wk 1 and 6

wk 2 post-weaning (P < 0.01). Even though sows fed the B diet had a numerical 7

decrease in feed intake (5.74 kg/d) and energy consumption (15.81 Mcal ME/d) than 8

sows fed the C diet (5.88 kg/d and 18.65 Mcal ME/d, respectively) over the 42 d 9

feeding period (Table 2), they were also less efficient (0.17 kg gain/kg feed) 10

compared to C sows (0.20 kg gain/kg feed) (P < 0.01) for the 42 d study. This was 11

due in part to lower feed efficiency rates during wks 1 (-0.65 vs. -0.41, P < 0.10) and 12

4 (0.21 vs. 0.26, P < 0.10) post-weaning. Negative growth and feed efficiency values 13

were observed for most sows during the first week post-weaning due to high levels of 14

water loss during the post-suckling period. 15

As expected, sows fed the lower energy B diet tended to accumulate less backfat 16

from weaning to d 21 post-weaning (0.86 mm, P < 0.05), and over the entire 42 d 17

feeding period (1.46 mm, P < 0.01) compared to sows fed the higher energy C diet. 18

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These results are in agreement with those reported from a previous study 1

(Fernandez et al., 1986) that showed that sows are relatively efficient in utilizing 2

high fiber feedstuffs (barley and sunflower meal), compared to growing pigs. 3

However, another study (Pollman et al., 1979) indicated that as the fiber content of 4

the diet increases, digestibility of fiber, energy, and nitrogen decreases when 5

comparing diets containing sun-cured alfalfa, tall wheat straw, and corn-soybean 6

meal. These two studies suggest that both source and level of dietary fiber need to 7

be considered when developing feeding programs to optimize nutrient (energy) 8

utilization in sows. 9

Results from this study suggest that a lower energy, higher fiber diet, such as the 10

barley-sunflower diet provided in this experiment, allows reasonable gains and 11

efficiency of gain with less backfat gain over a 42 d feeding period. However, the 12

feeding of a corn-soybean meal diet results in heavier sows at the end of the feeding 13

period. 14

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Sow Responses to Feeding Level the First Week Post-Weaning 16

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There were no differences in overall average daily gain between sows that were 18

limit-fed (L) or full-fed (AL) the C or B diet during wk 1. During the wk 1 post-19

weaning, limit-fed sows lost an average of 1.88 kg/d, while full-fed sows lost an 20

average of 1.03 kg/d (Table 2), a 45% reduction in body weight loss (P < 0.01). 21

However, the 6.0 kg difference in total body weight loss between limit-fed and full-22

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fed sows at the end of week 1 was almost completely recovered at the end of the 42 d 1

experimental period (239.4 vs 235.0 kg) (P > 0.20). This suggests that sows that are 2

nutrient restricted during the first week post-weaning achieve compensatory gain 3

during subsequent feeding periods. 4

Sows that were limit-fed during the first week after weaning had similar 5

increases in backfat accretion (8.24 mm) during the 42 d feeding period compared to 6

sows that were full-fed during week 1 (8.32 mm) (P = 0.89). Sows that were limit-fed 7

during the first week after weaning, however, ate 13.4 kg less feed (237.3 vs. 250.7 8

kg) (P < 0.05) than full-fed sows during the entire 42 d feeding period, and appeared 9

to be slightly more efficient in converting feed to body weight gain (0.182 vs. 0.191 10

kg of gain/kg feed, respectively; P = 0.12). These results suggest there may be a 11

slight advantage of limit feeding sows during the first week after weaning to reduce 12

overall feed cost/kg of gain. 13

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Sow Responses to Pregnancy Status Post-Weaning 15

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Sows that were mated as they returned to estrus after weaning, and remained 17

pregnant over the 42 d feeding period (P), gained an average of 0.26 kg/sow/d more 18

(P < 0.01) than sows that were not pregnant (N) during the study (Table 2). Much 19

of this weight gain advantage occurred during wk 4 of the feeding period, when P 20

sows gained 1.09 kg/d while N sows gained only 0.10 kg/d (P < 0.01). The minimal 21

weight gain experienced by non-pregnant sows during week 4 can be most likely 22

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attributed to the fact that those sows returned to estrus during this week and 1

consumed 8.05 kg less feed than pregnant sows (P < 0.01). However, the majority of 2

the weight gain advantage of pregnant sows was due to higher average daily feed 3

consumption (6.04 vs. 5.58 kg/d) (P < 0.01) over the 42 d feeding period. Pregnant 4

sows also were more efficient (P < 0.01) in converting feed to body weight gain 5

(0.202 kg gain/kg feed) than non-pregnant sows (0.171 kg gain/kg feed). However, 6

pregnant sows had an increased (30%) rate of backfat deposition, resulting in a 7

greater proportion of body weight gain being attributed to backfat deposition (P < 8

0.01). 9

Nutrient utilization, body weight and compositional changes are different 10

between pregnant and non-pregnant sows (Close et al., 1984; Noblet et al., 1985; 11

Close et al., 1985). In the pig there is a conflict of evidence on the extent to which 12

maternal nutrition influences fetal growth. If there is a range of feed intakes over 13

which fetal growth and development is independent of maternal nutrition, then 14

there is likely to be a range in which nutrients are partitioned between maternal and 15

reproductive tissues (Close et al., 1984). Net maternal gain and the differences 16

between pregnant and non-pregnant animals have been shown to vary with both 17

feeding level and stage of gestation (Close et al., 1984). 18

These results may suggest that hormonal patterns associated with pregnancy have 19

a large effect on body weight gain, ad libitum feed intake and gain efficiency, and 20

that increased nutrient partitioning toward maternal growth appears to occur. 21

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Sow Responses to Feeding Level, Dietary Energy Density, and Pregnancy Status Post-1

Weaning 2

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Despite the fact that sows lose body weight after weaning while consuming 4

considerable amounts of feed (Shurson et al., 1991), feeding a low metabolizable 5

energy density barley-sunflower meal diet, further increases body weight loss 6

(Tables 2, 3, and 4), regardless of whether sows are limit- or full-fed during the first 7

week post-weaning (P < 0.01). As expected, no effect on weight loss during wk 1 8

post-weaning can be attributed to whether or not sows are mated as they return to 9

estrus within that time period (Table 2). Pregnancy status, however, significantly 10

affects growth, feed intake and efficiency, and backfat accretion the first 6 wks post-11

weaning (Table 2), regardless of diet (Table 4) or feeding level wk 1 post-weaning 12

(Table 5) (P < 0.10). One study has shown that loss of body water at weaning is 13

considerable, but is significantly less than that which occurs in the fasted animal, 14

and depletion of body tissue (including protein) occurs in the newly weaned sow 15

(Zoiopoulos, 1983). Therefore, in order to minimize sow weight loss during the first 16

week post-weaning, sows should be fed a corn-soybean meal diet ad libitum. Mating 17

sows further improves growth performance and feed conversion. 18

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Economic Analysis of Different Manangement Regimes on Marketing Cull Sows at 3 20

or 6 Weeks Post-weaning 21

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Results of an economic analysis of the results achieved from this trial are 1

presented in Tables 6-9. Net profitability per sow marketed is presented for each 2

factor included, in addition to the estimated feed consumed and body weight gained 3

that is assumed in the model. Including the presence of a wet sow discount of 4

$0.07/kg live weight in the model resulted in an additional $1.12 to $3.83 / cull sow 5

marketed, dependent on feeding and/or management factors and feed costs and sow 6

prices included, but did not guarantee a net profit for marketing cull sows at 3- or 6-7

weeks post-weaning. In general, feeding for 6 weeks post-weaning was 8

advantageous compared to 3 weeks only when sow price was high ($0.90/kg) and 9

feed cost low ($0.10). When net return was near or below break-even, feeding for 3 10

weeks was more economically advantageous than feeding for 6 weeks. This indicates 11

that if market prices are such that it is economically justified to feed cull sows, then 12

a 6-week period is preferable to a 3-week period. 13

Sows that were mated and pregnant, and sows that were fed the corn-soybean 14

meal diet had the greatest economic returns. There was no appreciable difference in 15

feeding level the first week post-weaning on net profitability. Combining the P and 16

C factors resulted in additional increases in net profitability. However, this 17

economic model doesn’t consider a difference in feed cost between the C and B diets, 18

nor does is consider the cost associated with breeding a sow. Although these costs 19

should be relatively low, they will decrease the expected net return for each of these 20

strategies. The least profitable scenarios occurred when sows were not mated (NP) 21

and/or were fed the B diets. 22

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Implications 2

3

Ad libitum feeding during the first week post-weaning increased overall ADFI 4

and tended to improve ADG and sow weight loss wk 1 post-weaning, but did not 5

affect overall growth performance, sow body weight, or backfat accretion. 6

Additionally, it did not appear to appreciably affect net return per cull sow 7

marketed. Feeding a barley-sunflower meal diet decreased ADG and feed efficiency, 8

and appeared to lower ADFI slightly. Compared to non-mated sows, sows that were 9

mated immediately post-weaning had increased ADG, ADFI, G/F, and backfat levels 10

for the 42 d trial. Sows that were pregnant and/or fed a corn-soybean meal had the 11

greatest net returns when fed for 3- or 6-weeks post-weaning. These results suggest 12

that maximum growth and feed efficiency to increase the marketing weight of cull 13

sows can be achieved by mating sows as they return to estrus post-weaning and 14

providing a corn-soybean meal diet. Maximum net economic returns may be 15

achieved by implementing this strategy for 6 weeks post-weaning. Further 16

improvements to feed efficiency may be achieved by restricting feed intake the first 17

wk post-weaning. However, it is a combination of other factors, including feed cost 18

and sow price (wet and dry), that determines whether to market cull sows wet, or 19

which diet to be fed and for what period of time if marketing cull sows dry. 20

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Literature Cited 1

2

Close, W. H., J. Noblet, and R. P. Heavens. 1984. The partition of body-weight 3

gain in the pregnant sow. Livestock Prod. Sci. 11:517-527. 4

Close, W. H., J. Noblet, and R. P. Heavens. 1985. Studies on energy metabolism of 5

the pregnant sow: The partition and utilization of metabolizable energy 6

intake in pregnant and non-pregnant animals. Brit. J. Nutr. 53:267-279. 7

Fernandez, J. A., H. Jorgensen, and A. Just. 1986. Comparative digestibility 8

experiments with growing pigs and adult sows. Anim. Prod. 43:127-132. 9

Noblet, J., W. H. Close, and R. P. Heavens. 1985. Studies on the energy metabolism 10

of the pregnant sow: Uterus and mammary tissue development. Brit. J. 11

Nutr. 53:251-265. 12

NRC. 1988. Nutrient requirements of swine. 9th ed. National Academy Press, 13

Washington, DC. 14

Plain, R. L. and G. C. Shurson. 1999. Marketing cull sows. Pork Ind. Hand. No. 15

123. Purdue Univ. Coop. Ext. Ser., West Lafayette, Ind. 16

Pollman, D. S., D. M. Danielson, and E. R. Peo, Jr. 1979. Value of high fiber diets 17

for gravid swine. J. Anim. Sci. 48:1385-1393. 18

SAS. 1985. SAS User’s Guide: Statistics. SAS Inst., Inc., Cary, NC. 19

Shurson, G. C., G. A. Isler, K. M. Irvin, and G. A. Peterson. 1991. Traits affecting 20

post-weaning weight gain and feed intake of primiparous sows. J. Anim. Sci. 21

69:3487-3493. 22

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Zoiopoulos, P. E., J. H. Topps, and P. R. English. 1983. Losses in weight and body 1

water in sows after weaning. Brit. J. Nutr. 50:163-172.2

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Table 1. Percentage composition of experimental diets (as-fed basis)

Barley- Corn-Sunflower Soybean

Item meal (B)a meal (C)b

Ingredient, % Corn ______ 86.08 Barley 84.03 ______

Soybean meal (44% CP) ______ 10.00 Sunflower meal (38%CP) 12.50 ______

Dicalcium phosphate 0.95 1.75 Limestone 1.20 0.85 Salt 0.50 0.50 TMVPc 0.82 0.82

aFormulated to 14.6% CP, 0.52% lysine, 2754 kcal ME/kg, 4.29% crudefiber, 0.76% Ca, and 0.60% P.

bFormulated to 12.2% CP, 0.52% lysine, 3172 kcal ME/kg, 2.29% crudefiber, 0.75% Ca, and 0.60% P.

cIndividual station trace mineral and vitamin premixes used, with varyinglevels substituted with grain. Biotin premix, choline chloride, and folic acidincluded at 20, 1063, and 9 g/ton, respectively.

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Table 2. Least squares means comparison of pregnancy status, feeding level, and diet

Non- Ad Limit Barley CornPreg Preg Lib Fed Sun Soy

Item (NP) (P) P -value (AL) (L) P -value (B) (C) P -value SEM

No. sows 147 122 --- 132 137 --- 133 136 --- ---Parity 2.68 2.72 0.84 2.73 2.67 0.81 2.79 2.6 0.39 0.15 Sow wt, kg Farrow 206.8 206.3 0.92 206.7 206.5 0.96 205.7 207.4 0.72 3.23 Wean (d 0) 193.2 190.9 0.54 193.0 191.1 0.62 191.4 192.6 0.75 2.73 End (d 42) 232.9 241.6 0.03 239.4 235.0 0.26 232.8 241.7 0.03 2.83

ADG, kg Wk 1 -1.42 -1.49 0.66 -1.03 -1.88 0.001 -1.65 -1.26 0.01 0.21 Wk 2 2.55 2.88 0.02 2.43 3.00 0.001 2.59 2.84 0.08 0.21 Wk 3 1.70 1.84 0.17 1.74 1.80 0.56 1.74 1.80 0.54 0.14 Wk 4 0.10 1.09 0.001 0.48 0.72 0.11 0.56 0.63 0.67 0.22 Wk 5 1.52 1.69 0.26 1.61 1.59 0.88 1.44 1.77 0.03 0.22 Wk 6 1.24 1.24 0.95 1.27 1.22 0.65 1.25 1.23 0.83 0.17 Wk 1-6 0.95 1.21 0.001 1.08 1.07 0.80 0.99 1.17 0.001 0.06

ADFI, kg Wk 1 2.83 2.81 0.89 3.55 2.08 0.001 2.56 3.07 0.001 0.22 Wk 2 5.73 5.89 0.37 5.92 5.69 0.21 5.55 6.07 0.01 0.26 Wk 3 6.67 7.01 0.07 6.87 6.87 0.79 6.74 6.94 0.30 0.28 Wk 4 5.74 6.89 0.001 6.31 6.32 0.96 6.43 6.20 0.24 0.29 Wk 5 5.99 6.79 0.001 6.36 6.42 0.73 6.38 6.40 0.91 0.25 Wk 6 6.51 6.88 0.05 6.81 6.58 0.25 6.80 6.59 0.28 0.28 Wk 1-6 5.58 6.04 0.001 5.97 5.65 0.02 5.74 5.88 0.29 0.19

G/F Wk 1 -0.502 -0.535 0.25 -0.293 -0.902 0.02 -0.645 -0.417 0.07 0.520 Wk 2 0.483 0.529 0.10 0.441 0.571 0.001 0.508 0.504 0.91 0.039 Wk 3 0.257 0.265 0.67 0.245 0.277 0.08 0.256 0.266 0.57 0.026 Wk 4 -0.169 0.169 0.07 -0.115 0.115 0.22 -0.099 0.100 0.28 0.271 Wk 5 0.226 0.248 0.44 0.238 0.236 0.93 0.210 0.264 0.06 0.041 Wk 6 0.198 0.189 0.70 0.183 0.205 0.32 0.200 0.187 0.55 0.032 Wk 1-6 0.171 0.202 0.001 0.182 0.191 0.12 0.170 0.203 0.001 0.008

Chg in backfat, mm d 0-21 2.63 3.00 0.36 3.12 2.51 0.13 2.39 3.25 0.03 0.59 d 21-42 4.56 6.37 0.001 5.21 5.71 0.27 5.18 5.75 0.21 0.67 d 0-42 7.20 9.36 0.001 8.32 8.24 0.89 7.55 9.01 0.01 0.79

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Table 3. Effects of a diet type x feeding level interaction on ADG, ADFI, G/F, and change in backfat thickness values of cull sows d 0 - 42 post-weaning

Corn-soybean meal (C) Barley-sunflower meal (B) Significance (P -value)

Ad-libitum Limit Ad-libitum Limit CAL vs BAL vs CAL vs CL vsItem feeding (AL) feeding (L) feeding (AL) feeding (L) CL BL BAL BL

ADG, kg 1.16 1.18 1.01 0.97 0.66 0.42 0.01 0.001

ADFI, kg 5.97 5.79 5.97 5.51 0.32 0.02 0.99 0.13

G/F 0.198 0.208 0.167 0.174 0.18 0.37 0.001 0.001

BF change, mm 8.95 9.07 7.68 7.42 0.88 0.73 0.09 0.03

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Table 4. Effects of a diet type x pregnancy status interaction on ADG, ADFI, G/F, and change in backfat thickness values of cull sows d 0 - 42 post-weaning

Corn-soybean meal (C) Barley-sunflower meal (B) Significance (P -value)

Pregnant Non- Pregnant Non- CP vs BP vs CP vs CN vsItem (P) pregnant (N) (P) pregnant (N) CN BN BP BN

ADG, kg 1.28 1.06 1.14 0.84 0.001 0.001 0.02 0.001

ADFI, kg 6.03 5.73 6.06 5.43 0.09 0.001 0.89 0.09

G/F 0.216 0.190 0.188 0.152 0.001 0.001 0.001 0.001

BF change, mm 10.03 7.99 8.69 6.41 0.006 0.003 0.09 0.03

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Table 5. Effects of a feeding level x pregnancy status interaction on ADG, ADFI, G/F, and change in backfat thickness values of cull sows d 0 - 42 post-weaning

Ad-libitum feeding (AL) Limited feeding (L) Significance (P -value)

Pregnant Non- Pregnant Non- ALP vs LP vs ALP vs ALN vsItem (P) pregnant (N) (P) pregnant (N) ALN LN LP LN

ADG, kg 1.24 0.93 1.18 0.96 0.001 0.001 0.35 0.52

ADFI, kg 6.22 5.72 5.87 5.43 0.01 0.02 0.07 0.10

G/F 0.200 0.165 0.205 0.177 0.001 0.001 0.53 0.10

BF change, mm 9.01 7.62 9.71 6.78 0.07 0.001 0.38 0.25

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Table 6. Economic analysis of different feeding and management regimens over a 3 week post-weaningperiod, assuming no wet sow discount, on net profitability per cull sow marketed 1

Feeding Profit ($/sow) Feed Ending Sow Price = $0.90/kg Sow Price = $0.70/kg Trt Consumed Sow Wt Feed cost / kg Feed cost / kg

Group (kg) (kg) $0.10 $0.15 $0.10 $0.15

Pregnant (P) 109.8 212.2 4.48 -1.01 0.04 -5.45Non-pregnant (NP) 106.5 209.6 2.48 -2.85 -1.44 -6.76

Ad libitum (AL) 114.2 211.5 3.40 -2.31 -0.89 -6.60Limit-fed (L) 102.1 210.3 3.54 -1.56 -0.51 -5.62

Corn-soy (C) 112.4 213.2 5.14 -0.48 0.50 -5.12Barley-sun (B) 103.9 208.6 1.81 -3.38 -1.90 -7.09

P + AL 116.0 213.5 5.04 -0.76 0.34 -5.46P + L 103.6 210.9 3.93 -1.25 -0.25 -5.42P + C 113.9 214.4 6.07 0.37 1.19 -4.51P + B 105.7 210.0 2.89 -2.40 -1.10 -6.39NP + AL 112.3 209.5 1.79 -3.83 -2.11 -7.72NP + L 100.7 209.7 3.17 -1.86 -0.77 -5.81NP + C 110.9 212.0 4.22 -1.32 -0.18 -5.73NP + B 102.2 207.2 0.74 -4.37 -2.69 -7.80AL + C 118.7 213.1 4.40 -1.53 -0.21 -6.15AL + B 109.7 209.9 2.45 -3.04 -1.53 -7.02L + C 106.1 213.4 5.90 0.60 1.23 -4.07L + B 98.2 207.2 1.20 -3.71 -2.25 -7.16

P + AL + C 122.0 215.5 6.22 0.12 1.13 -4.97P + AL + B 110.0 211.5 3.85 -1.65 -0.45 -5.95P + L + C 105.9 213.3 5.89 0.60 1.23 -4.07P + L + B 101.2 208.4 1.95 -3.11 -1.73 -6.79NP + AL + C 115.4 210.6 2.54 -3.23 -1.59 -7.36NP + AL + B 109.3 208.3 1.03 -4.43 -2.62 -8.09NP + L + C 106.4 213.4 5.90 0.58 1.22 -4.09NP + L + B 95.1 206.1 0.45 -4.30 -2.76 -7.52

1 Assumes initial weaned sow weight of 190 kg and nonfeed cost of $1.50/week/sow marketed.

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Table 7. Economic analysis of different feeding and management regimens over a 3 week post-weaningperiod, assuming a $ 0.07/kg live weight wet sow discount, on net profitability per cull sow marketed 1

Feeding Profit ($/sow) Feed Ending Sow Price = $0.90/kg Sow Price = $0.70/kg Trt Consumed Sow Wt Feed cost / kg Feed cost / kg

Group (kg) (kg) $0.10 $0.15 $0.10 $0.15

Pregnant (P) 109.8 212.2 6.03 0.54 1.59 -3.90Non-pregnant (NP) 106.5 209.6 3.85 -1.47 -0.07 -5.39

Ad libitum (AL) 114.2 211.5 4.90 -0.81 0.61 -5.10Limit-fed (L) 102.1 210.3 4.96 -0.14 0.91 -4.20

Corn-soy (C) 112.4 213.2 6.77 1.15 2.13 -3.49Barley-sun (B) 103.9 208.6 3.11 -2.08 -0.60 -5.80

P + AL 116.0 213.5 6.69 0.89 1.99 -3.81P + L 103.6 210.9 5.39 0.21 1.22 -3.96P + C 113.9 214.4 7.78 2.08 2.89 -2.80P + B 105.7 210.0 4.28 -1.00 0.29 -4.99NP + AL 112.3 209.5 3.15 -2.47 -0.74 -6.36NP + L 100.7 209.7 4.55 -0.48 0.61 -4.43NP + C 110.9 212.0 5.76 0.22 1.36 -4.19NP + B 102.2 207.2 1.94 -3.17 -1.49 -6.60AL + C 118.7 213.1 6.02 0.08 1.40 -4.53AL + B 109.7 209.9 3.84 -1.64 -0.14 -5.62L + C 106.1 213.4 7.54 2.23 2.87 -2.44L + B 98.2 207.2 2.41 -2.50 -1.04 -5.95

P + AL + C 122.0 215.5 8.01 1.91 2.91 -3.19P + AL + B 110.0 211.5 5.35 -0.15 1.05 -4.45P + L + C 105.9 213.3 7.52 2.23 2.86 -2.43P + L + B 101.2 208.4 3.24 -1.82 -0.44 -5.51NP + AL + C 115.4 210.6 3.99 -1.78 -0.14 -5.91NP + AL + B 109.3 208.3 2.31 -3.15 -1.34 -6.81NP + L + C 106.4 213.4 7.54 2.22 2.86 -2.46NP + L + B 95.1 206.1 1.57 -3.18 -1.64 -6.39

1 Assumes initial weaned sow weight of 190 kg and nonfeed cost of $1.50/week/sow marketed.

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Table 8. Economic analysis of different feeding and management regimens over a 6 week post-weaningperiod, assuming no wet sow discount, on net profitability per cull sow marketed 1

Feeding Profit ($/sow) Feed Ending Sow Price = $0.90/kg Sow Price = $0.70/kg Trt Consumed Sow Wt Feed cost / kg Feed cost / kg

Group (kg) (kg) $0.10 $0.15 $0.10 $0.15

Pregnant (P) 253.7 240.8 11.35 -1.33 1.19 -11.50Non-pregnant (NP) 234.4 229.9 3.47 -8.25 -4.51 -16.23

Ad libitum (AL) 250.7 235.4 6.79 -5.74 -2.29 -14.83Limit-fed (L) 237.3 234.9 7.68 -4.19 -1.30 -13.17

Corn-soy (C) 247.0 239.1 10.49 -1.86 0.67 -11.68Barley-sun (B) 241.1 231.6 4.33 -7.73 -3.99 -16.05

P + AL 261.2 241.9 11.61 -1.45 1.22 -11.84P + L 246.6 239.6 11.02 -1.31 1.09 -11.24P + C 253.3 243.7 13.97 1.31 3.24 -9.43P + B 254.4 237.8 8.61 -4.10 -0.95 -13.67NP + AL 240.4 229.1 2.16 -9.86 -5.67 -17.68NP + L 228.2 230.5 4.66 -6.75 -3.45 -14.86NP + C 240.5 234.4 6.94 -5.09 -1.95 -13.97NP + B 228.0 225.2 -0.13 -11.53 -7.16 -18.57AL + C 250.7 238.6 9.63 -2.91 -0.08 -12.62AL + B 250.8 232.5 4.14 -8.40 -4.35 -16.89L + C 243.1 239.6 11.33 -0.83 1.41 -10.75L + B 231.6 230.6 4.35 -7.23 -3.76 -15.34

P + AL + C 259.0 244.7 14.32 1.37 3.38 -9.57P + AL + B 263.3 239.1 8.85 -4.31 -0.97 -14.13P + L + C 247.7 242.7 13.67 1.29 3.13 -9.25P + L + B 245.5 236.6 8.37 -3.90 -0.94 -13.22NP + AL + C 242.4 232.4 4.90 -7.22 -3.58 -15.70NP + AL + B 238.3 225.8 -0.62 -12.53 -7.78 -19.69NP + L + C 238.6 236.5 8.95 -2.98 -0.34 -12.27NP + L + B 217.8 224.6 0.33 -10.56 -6.58 -17.47

1 Assumes initial weaned sow weight of 190 kg and nonfeed cost of $1.50/week/sow marketed.

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Table 9. Economic analysis of different feeding and management regimens over a 6 week post-weaningperiod, assuming a $ 0.07/kg live weight wet sow discount, on net profitability per cull sow marketed 1

Feeding Profit ($/sow) Feed Ending Sow Price = $0.90/kg Sow Price = $0.70/kg Trt Consumed Sow Wt Feed cost / kg Feed cost / kg

Group (kg) (kg) $0.10 $0.15 $0.10 $0.15

Pregnant (P) 253.7 240.8 14.91 2.22 4.75 -7.94Non-pregnant (NP) 234.4 229.9 6.26 -5.46 -1.72 -13.44

Ad libitum (AL) 250.7 235.4 9.97 -2.57 0.89 -11.65Limit-fed (L) 237.3 234.9 10.82 -1.04 1.84 -10.02

Corn-soy (C) 247.0 239.1 13.93 1.58 4.11 -8.24Barley-sun (B) 241.1 231.6 7.24 -4.81 -1.08 -13.13

P + AL 261.2 241.9 15.24 2.18 4.86 -8.20P + L 246.6 239.6 14.50 2.17 4.57 -7.76P + C 253.3 243.7 17.73 5.06 7.00 -5.67P + B 254.4 237.8 11.96 -0.76 2.40 -10.32NP + AL 240.4 229.1 4.89 -7.13 -2.93 -14.95NP + L 228.2 230.5 7.50 -3.91 -0.61 -12.02NP + C 240.5 234.4 10.05 -1.98 1.16 -10.86NP + B 228.0 225.2 2.34 -9.06 -4.70 -16.10AL + C 250.7 238.6 13.03 0.49 3.32 -9.22AL + B 250.8 232.5 7.11 -5.43 -1.38 -13.92L + C 243.1 239.6 14.80 2.64 4.88 -7.28L + B 231.6 230.6 7.19 -4.39 -0.92 -12.50 P + AL + C 259.0 244.7 18.15 5.20 7.21 -5.74P + AL + B 263.3 239.1 12.29 -0.88 2.47 -10.70P + L + C 247.7 242.7 17.36 4.98 6.82 -5.56P + L + B 245.5 236.6 11.63 -0.64 2.32 -9.96NP + AL + C 242.4 232.4 7.86 -4.26 -0.61 -12.73NP + AL + B 238.3 225.8 1.88 -10.03 -5.27 -17.19NP + L + C 238.6 236.5 12.20 0.27 2.91 -9.02NP + L + B 217.8 224.6 2.75 -8.14 -4.16 -15.05

1 Assumes initial weaned sow weight of 190 kg and nonfeed cost of $1.50/week/sow marketed.