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Small Ruminant Research 94 (2010) 167–175

Contents lists available at ScienceDirect

Small Ruminant Research

journa l homepage: www.e lsev ier .com/ locate /smal l rumres

nvestigation of growth and carcass characteristics of pure androssbred Awassi lambs

bdullah Y. Abdullaha,∗, Rami T. Kridli a, M. Momani Shakerb, Mohammad D. Obeidata

Department of Animal Production, Faculty of Agriculture, Jordan University of Science and Technology, Irbid 22110, JordanInstitute of Tropical and Subtropical Agriculture, Czech University of Agriculture, Prague, Czech Republic

r t i c l e i n f o

rticle history:eceived 25 April 2010eceived in revised form 11 August 2010ccepted 12 August 2010vailable online 9 September 2010

eywords:rowtharcass characteristicsure Awassirossbred Awassiambs

a b s t r a c t

The aim of this experiment was to study the growth performance of both ram and ewelambs, and the carcass characteristics of ram lambs of five genotypes: Awassi (A), F1

Charollais–Awassi (CA), F1 Romanov–Awassi (RA), B1 Awassi–(Charollais × Awassi) (ACA)and B1 Awassi–(Romanov × Awassi) (ARA). One-hundred lambs (50 females and 50 males)were separated into 10 groups according to sex and genotype from weaning until the endof the experiment. Birth and weaning weights were recorded for all animals; live weightwas recorded for all animals on bi-weekly intervals between 2 and 8 months of age. At 8months of age, 6 ram lambs from each genotype (a total of 30 ram lambs) were randomlychosen for slaughter. Birth weights were similar while weaning weights differed amongthe five genotypes being greater for the CA. Post-weaning live weights differed amonggenotypes and according to lamb’s sex (P < 0.01). Genotype and lamb sex had significanteffects on the total weight gain and average daily gain (ADG) from birth till the end of theexperiment. The CA lambs outperformed other genotypes while ram lambs had better per-formance than ewe lambs. The greatest ADG for all genotypes occurred during the periodfrom weaning to 5 months of age (fattening period). At slaughter, final live weight wasfound to be significantly affected by genotype; the greatest weight was recorded for CAgenotype (62.5 ± 4.0 kg). Slaughter weight and hot and cold carcass weights differed sig-nificantly among the five genotypes with Awassi having the lightest weights. Dressing-outpercentage was also affected by genotype with CA lambs having the greatest value. Awassihad lower eye muscle depth, the shorter carcass (P < 0.001), least fat tissue depth, lowestlinear measurements and the greatest fat tail percentage compared with the remaining

genotypes. Shoulder and rack percentages differed among the genotypes with Awassi hav-ing the lowest values. In the dissected leg cut, muscle to bone ratio differed among thegenotypes with CA having the highest ratio. Awassi lamb meat had lower (P < 0.05) drymatter and crude fat (on as wet basis) percentages than the other genotypes. Results ofthis study indicate that crossbreeding Awassi with exotic breeds improves growth rate andmeat production.

∗ Corresponding author at: Faculty of Agriculture, Jordan University ofcience and Technology, P.O. Box 3030, Irbid 22110, Jordan.el.: +962 2 7201000x22255; fax: +962 2 7201078.

E-mail address: abdullah@just.edu.jo (A.Y. Abdullah).

921-4488/$ – see front matter © 2010 Elsevier B.V. All rights reserved.oi:10.1016/j.smallrumres.2010.08.005

© 2010 Elsevier B.V. All rights reserved.

1. Introduction

Improving productive and reproductive traits of sheepcan be done using several approaches. Genetic improve-ment of animals is one of these approaches and canbe performed by selection, introducing new sires, cross-breeding or a combination of these methods. Progress in

minant

168 A.Y. Abdullah et al. / Small Ru

improving productive and reproductive traits, especiallyin growth and meat production characteristics, is a majoraim for sheep breeding because the efficiency of productionprimarily depends on these traits (Ibarra et al., 2000).

Owens et al. (1993) reported that growth rate and dailygain are the most important characteristics when studyingthe meat production of lambs. They found that Chios andAwassi lambs had significantly higher weights gains fromweaning to 35–40 kg than Cyorus fat-tailed lambs. More-over, Santra and Karim (2001) found that Awassi × Malpura(AM) reached a 25 kg of target weight earlier than bothA × AM (Awassi 75%, Malpura 25%) and Malpura genotypes.Santra and Karim (2001) concluded that crossbreedingimproves the growth performance of Malpura genotypeand that the first cross (AM) had a greater growth rate thanthe backcross (A × AM).

Factors that may affect lamb’s pre-weaning growthinclude genotype, sex, age and birth type (Suarez et al.,2000). Lamb sex is one of the most important factors affect-ing growth performance and gain. Ellis et al. (1997) andBennett et al. (1991) compared the growth performanceof ewe and wether lambs and found that ewe lambs werelighter than wether lambs at the same age.

Carcass traits are some of the most important character-istics that are affected by a lamb’s genotype. Crossbreedingwas found to improve slaughter and carcass traits of fat-tailed breeds mainly by reducing the total body fat (Farid,1991).

Part of the sheep flock at Jordan University of Sci-ence and Technology is undergoing genetic improvementthrough a crossbreeding program. In order to eval-uate the success of such a program, evaluating theoffspring performance is essential. Therefore, the studywas conducted to investigate the effect of crossbreed-ing on the growth performance of pure and crossbredram and ewe lambs and carcass characteristics of ramlambs.

2. Materials and methods

2.1. Animals and plane of nutrition

One-hundred lambs (50 females and 50 males) were used inthis experiment. Animals were divided into 10 groups according totheir sex and genotype. Five different genotypes from both sexeswere used as the following: F1 Charollais–Awassi (CA) genotype, B1

Awassi–(Charollais × Awassi) (ACA) genotype, F1 Romanov–Awassi (RA)genotype, B1 Awassi–(Romanov × Awassi) (ARA) genotype and pureAwassi genotype (A).

Lambs were selected randomly at weaning (80 ± 2 days) from thelambs born during lambing season. The five male groups and the fivefemales groups from each genotype were reared in 10 adjacent open sidedpens separating females from males. The experiment was started at thebeginning of March and lasted for 6 months. Total live weight gain andaverage daily gain were calculated during several stages: gain and ADG1 represent the period from birth to weaning, gain and ADG 2 representthe period from weaning to 185 days of fattening period, gain and ADG 3represent the period from 186 to 221 days of fattening period. By the endof the experiment, six ram lambs from each of the five genotypes wereslaughtered for the investigation of carcass characteristics.

A group feeding system was used to feed the animals. The formu-lated ration contained 16% crude protein and 2.78 Mcal metabolizableenergy/kg. Total mixed ration diets of ad libitum were provided twicea day (two equal meals at 9:00 am and 3:00 pm) allowing a refusal rateof 10% with free access to fresh water during the study. Feed intake andrefused feed were weighed and recorded daily to calculate the amount

Research 94 (2010) 167–175

of daily feed intake. Body weight was recorded for each individual ani-mal in the morning before feeding on bi-weekly intervals from the dateof weaning till the end of the experiment.

2.2. Slaughtering procedures and carcass composition

At the average age of 240 days, six ram lambs from each genotype wereslaughtered and dressed after a 12-h fasting period following the normalcommercial procedure (Abdullah et al., 1998). Animals were slaughteredby cutting the arteries and the jugular vein in the neck region and left tobleed for a few minutes. Immediately after bleeding, animals were flayedand eviscerated always in the same order.

Final and slaughter weights were recorded before slaughtering. Heart,liver, kidneys, lungs and trachea, spleen, both testes, mesenteric and kid-ney fat were all weighed and recorded immediately after being removedfrom the animal. Hot carcass weight was also recoded for all carcasses.Carcasses were kept in the chiller for approximately 24 h at 1–4 ◦C, beforebeing weighed to obtain the cold carcass weights. Tail fat weight wasdetermined after being separated from the area around the hind legs ofthe ram lamb’s carcasses. Some linear measurements were applied to eachof the whole carcasses using a metal meter and big caliper. These include:body length (LB), leg length (T), width behind the shoulders (WTH), max-imum shoulder width (WF) and gigot width (G).

After completing the above measurements, carcasses were cut intofour parts (shoulder, rack, loin and leg) following the normal commercialprocedure described by Abdullah et al. (1998). Shoulders were separatedfrom the rack by first cutting with the knife along a line against the caudaledge of the 7th rib on each side, and then the vertebra was sawn through.Rack was separated from the loin by cutting against the caudal edge of the12th rib, the ventral edge of the costal cartilages and through the inter-vertebral joint between the 12th and 13th thoracic vertebra. Leg and loinwere separated by cutting between the last and the second to last lumbervertebra.

All these cuts and the remaining tail were weighed and then a numberof other measurements were applied to the surface of each cut, thesemeasurements include: tissue depth (GR), rib fat depth (J), leg fat depth(L3), shoulder fat depth (S2), eye muscle width (A), eye muscle depth (B)and fat depth (C). When these measurements were recorded, the right(leg, loin and rack) side of each carcass was frozen at −20 ◦C in order to bedissected after being sealed in plastic bags.

Right after the freezing period, all cuts were randomly taken from thefreezer and were thawed in a cooler at 1–2 ◦C for 12 h preparing them fordissection. Cuts were weighed then dissected quickly to avoid moistureloss. The dissection operation included the separation of muscles, subcu-taneous and intermusculer fat and bones of each cut. M. Semitendonosus,M. Semimembrenosus, M. biceps, M. quadriceps and M. adductor mus-cles of each leg cut were separated and weighed individually. Moreover,femur and tibia bones were removed from the leg cuts, scraped, cleaned,weighed and their length and circumference recorded. All of the dissectedtissue parts were weighed immediately after their separation from thecuts.

Selected muscles and bones dissected from the right leg were usedto calculate muscularity values using the procedure described by Purchaset al. (1991) as the ratio of an index of muscle depth to the length of anadjacent bone (Lb), where the index of depth was obtained by taking thesquare root of an index of the average cross-sectional area of the muscleweight (Wm) over the length of the adjacent bone.

Muscularity =√

Wm/LbLb

2.3. Chemical analysis

For chemical analysis, meat from each dissected carcass was mincedand mixed together. Then a homogenized sample from each carcass wascollected to determine moisture, ash, ether extract (EE) and crude pro-

tein (CP) according to the AOAC (1990) procedures. Meat samples wereanalyzed for moisture (100 ◦C in an air-forced oven for 24 h; method967.3), ash (550 ◦C in an ashing furnace for 6 h; method 942), CP (Kjel-dahl procedure; method 976.06) and EE (Soxtec procedure, SXTEC SYSTEMHT 1043 Extraction unit, TECATOR, Box 70, Hoganas, Sweden; method920.29).

A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175 169

F ning triaa

2

dAdaervafcd

3

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sFflnaiAabadaw

ig. 1. Shows live body weight changes from birth to the end of the fattend female (D) lambs, of the five different genotypes.

.4. Statistical analysis

Data was analyzed by the analysis of variance of the complete ran-omized design using the general linear model procedure of SAS (2000).ll lambs from both sexes were used in a 5 × 2 factorial arrangement toetermine the effect of crossbreeding on average daily gain, total gainnd feed intake. Average gain data was analyzed using the general lin-ar model with a completely randomized design considering time asepeated measures and genotype, sex and sex × genotype interaction asariables. Carcass and non-carcass characteristics were determined usingSAS procedure (SAS, 2000) in a model adjusted by covariance analysis

or differences in the appropriate covariate. Least square means were cal-ulated for all variables in the study and a protected LSD test was used toetermine the significance differences.

. Results and discussion

.1. Live weight and feed intake

Body weight changes for all genotypes across bothexes are presented in Fig. 1(A) and (B). Lambs of the1CA genotype were always superior in the live weightollowed by B1ACA, F1RA, B1ARA and pure A genotypeambs, respectively. In general, F1CA lambs genotype sig-ificantly differed in some growth periods from lambs ofll genotypes. However, B1ACA and F1RA lambs had a sim-lar performance while being better than B1ARA and pure

lambs. A previous study conducted by Momani Shaker etl. (2002) reported that the Awassi genotype had a lower

irth weight and a higher weaning weight than both F1CAnd F1RA genotypes. These differences may be due to goodam management and a higher plane of nutrition whichffects not only birth weight, but also weaning weight asell (Darwisha et al., 2010; Cloete et al., 2007; Godfrey

l for: (A) male and (B) female lambs. Also shown, feed intake in male (C)

and Dodson, 2003). On the contrary, Young and Dickerson(1991) reported that genotype did not affect birth weightwhile significantly affecting weaning weight.

Several authors reported that sex had highly significanteffects on live body weight and weight gain, with maleshaving greater weight and gain than females (Hammelland Laforest, 2000; Al-Tarayrah and Tabbaa, 1999; MomaniShaker et al., 1996).

Average feed intake (kg/day) is presented in Fig. 1(C) and(D). Fig. 1(C) shows differences in feed intake among geno-types in favor of F1CA and F1RA ram lambs. Fig. 1(D) showssimilar feed intake among ewe lambs within the five geno-types. Feed intake ranged from 1.1 to 1.3 kg/head/day. F1CAewe lambs had the highest feed intake and F1RA ewe lambshad the lowest feed intake while the remaining genotypeswere intermediate.

Hassan et al. (1996) reported that the feed conversionratio was significantly affected by the lamb genotype, whilefeed consumption was not. This result was found by com-paring crosses of Chios and Ossimi breeds. Hammell andLaforest (2000) studied the effect of lamb sex on feed intakeand feed conversion ratio. They reported that sex had sig-nificantly affected both feed intake and feed conversionratio in favor of males. In addition, Abdullah et al. (1999)reported that there was a significant effect of lamb sex onfeed intake. They found that males consumed significantlymore feed than females.

3.2. Gain and average daily gain

Table 1 shows data for animal gain and average dailygain that is calculated for four stages. In general, highly

170 A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175

Table 1Least-squares means of weight gain (kg) and average daily gain (g).

Genotype × sex Age (days)

0–80 81–185 186–221 0–221

Gain ADG Gain ADG Gain ADG Gain ADG

1 (CA) 17.6 ± 0.9a 175 ± 10a 25.5 ± 1.9a 331 ± 24a 10.9 ± 1.3a 260 ± 32a 54.0 ± 3.0a 247 ± 14a

2 (ACA) 14.5 ± 0.8b 162 ± 8a 22.1 ± 1.6ab 294 ± 19ab 7.6 ± 1.0b 180 ± 24b 44.2 ± 2.3b 215 ± 11ab

3 (RA) 14.8 ± 0.6b 156 ± 6a 20.8 ± 1.2b 270 ± 14b 7.4 ± 0.8b 176 ± 18b 43.2 ± 1.7b 203 ± 8bd

4 (ARA) 12.5 ± 0.7bc 135 ± 8b 18.3 ± 1.5bc 242 ± 19bc 5.6 ± 1.0b 134 ± 25bc 36.1 ± 2.3c 171 ± 11c

5 (A) 11.8 ± 0.7c 161 ± 8a 16.4 ± 1.5c 221 ± 18c 5.2 ± 1.0b 123 ± 23c 33.7 ± 2.2c 179 ± 11cd

Female 13.8 ± 0.5 154 ± 5 17.7 ± 1.0b 235 ± 12b 7.0 ± 0.6 166 ± 15 38.5 ± 1.4b 186 ± 7b

Male 14.7 ± 0.5 162 ± 5 23.6 ± 1.0a 309 ± 12a 7.7 ± 0.7 183 ± 16 46.0 ± 1.5a 220 ± 7a

1 Female 16.1 ± 1.3 167 ± 14 20.1 ± 2.6 261 ± 32 9.5 ± 1.7 226 ± 40 45.7 ± 3.7bde 211 ± 18df

2 Female 14.2 ± 1.2 160 ± 13 20.0 ± 2.4 273 ± 30 7.5 ± 1.6 179 ± 37 41.7 ± 3.5bce 206 ± 17bcdf

3 Female 13.7 ± 0.8 142 ± 9 16.6 ± 1.7 216 ± 20 5.5 ± 1.1 130 ± 26 35.7 ± ± 2.4cf 167 ± 11ce

4 Female 13.7 ± 1.0 147 ± 11 16.8 ± 2.0 222 ± 25 7.0 ± 1.4 167 ± 33 37.9 ± 3.1ecf 178 ± 15de

5 Female 11.3 ± 1.1 153 ± 12 15.1 ± 2.3 201 ± 28 5.3 ± 1.5 126 ± 35 31.6 ± 3.2f 166 ± 16de

1 Male 19.1 ± 1.4 182 ± 15 30.9 ± 2.9 401 ± 35 12.4 ± 2.1 294 ± 49 62.4 ± 4.6a 283 ± 22a

2 Male 14.8 ± 1.0 163 ± 11 24.3 ± 2.0 316 ± 25 7.7 ± 1.3 182 ± 31 46.7 ± 2.9bd 224 ± 14bf

3 Male 15.9 ± 0.8 170 ± 9 25.0 ± 1.7 325 ± 20 9.3 ± 1.1 221 ± 26 50.7 ± 2.4d 239 ± 12ab

4 Male 11.3 ± 1.1 124 ± 12 19.9 ± 2.3 201 ± 28 4.2 ± 1.7 100 ± 37 34.3 ± 3.5cf 164 ± 17de

5 Male 12.4 ± 0.9 169 ± 10 17.8 ± 1.9 242 ± 23 5.0 ± 1.3 119 ± 31 35.9 ± 2.9cf 193 ± 14def

P-valueGenotype *** * ** ** ** ** *** ***

Sex NS NS *** *** NS NS *** ***

Genotype × sex NS NS NS NS NS NS ** *

‘a, b, c’ in the same column means a significant difference according to the indicated level of significance.Genotype 1 = F1 Carollais–Awassi genotype (F1CA), 2 = B1 Awassi–(Charollais × Awassi) genotype (B1ACA), 3 = F1 Romanov–Awassi genotype (F1RA), 4 = B1Awassi–(Romanov × Awassi) genotype (B1ARA), 5 = pure Awassi genotype (A).

NS: non-significant.

* P < 0.05.** P < 0.01.

*** P < 0.001.

significant effects of genotype and sex were found on bothparameters, except for the effect of sex at the stage frombirth to weaning (0–80 days) and from marketing age tonear puberty (186–221 days). Sex × genotype interactionssignificantly affected the total growth stage from birth tonear puberty (0–221 days). At the stage from birth to wean-ing (0–80 days of age), the B1ARA genotype had the lowestaverage daily gain (135 ± 8 g/day) while the F1CA genotypelambs recorded the greatest average daily gain (175 g/day).Live weight gain at this stage was the lowest for pure Agenotype lambs (11.8 ± 0.7 kg) while F1CA genotype lambshad the highest gain (17.6 ± 0.9 kg).

The highest increase in average daily gain was foundto be during the period from weaning to marketing age(81–185 days of age) for all genotypes of lambs. This rep-resents an increase in the average daily gain of the F1CAgenotype by 12.5%, 22.5%, 36.7% and 49.7% over the B1ACA,F1RA, B1ARA and A genotype lambs, respectively. The F1CAlambs were significantly different from all other geno-types in terms of average daily gain and gain at the stagefrom marketing to near puberty (186–221 days of age).The F1CA lambs grew faster than all other lambs in aver-age daily gain, which was calculated to be 44%, 47.7%, 94%and 111% higher than B1ACA, F1RA, B1ARA and A lambs,

respectively. In general, the highest gain and average dailygain of the F1CA genotype is a result of its highest weaningweight and the effect of the hybrid vigor that may occur inthe F1 generation when crossbreeding animals of differentbreeds.

A previous study by Momani Shaker et al. (2002)reported that the average daily gain for RA lambs washigher than both CA and Awassi lambs (311, 234 and207 g/day for RA, CA and Awassi genotypes, respectively).These differences may be due to the effect of type of cross-ing between different sire and dam, which may show theeffect of the hybrid vigor and may come from the effect ofthe plane of nutrition. Darwisha et al. (2010) and Crouse etal. (1981) reported that crossbreeding different genotypeswould significantly affect average daily gain. Kashan et al.(2005) reported that the immediate post-weaning periodis characterized by an increase in the rate of average dailygain in crossbred lambs compared with pure lambs. Breedsused in this study were Chaal and Zandi and their crosseswith rams of tailed breed (Zel). Güney (1990) reported thatADG for F1 generations was higher than for pure lambs.

Table 1 also shows that ram lambs were always superior(P < 0.001) to ewe lambs in both gain and average daily gainthroughout the whole experimental period (0–221 days ofage). The total average daily gain of male lambs was higherthan female lambs by 18.2% (220.7 g/day vs. 186.7 g/day). Atthe stage from weaning to marketing age, male lambs had31.4% greater average daily gain than female lambs, whilelive weight gain was 33.3% greater for male than female

lambs. Fernández et al. (2000) reported a greater feed con-version ratio of male lambs over female lambs. Moreover,Kashan et al. (2005) reported that sex of the lamb signif-icantly affects post-weaning average daily gain as well aslive weight gain.

A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175 171

Table 2Least-squares means of slaughtering data of the male Awassi and crossbred lambs.

Item Breed S.E. Significance

CA ACA RA ARA Awassi Breed Cova

Final weight (kg) 62.45a 55.73ab 62.37a 50.69bc 43.59c 3.70 ** *

Slaughter weight (kg) 58.35a 52.25ab 56.18ab 47.73bc 40.49c 3.63 * *

Hot carcass weight (kg) 27.22a 26.21ab 26.07ab 25.99ab 24.91b 0.45 * ***

Cold carcass weight (kg) 26.00a 24.46bc 24.80bc 24.84ab 23.65c 0.40 * ***

Dressing% 53.73a 51.20ab 51.66ab 49.67bc 47.22c 0.95 *** –Heart fat weight (g) 99 102 69 113 76 15.0 NS *

Heart weight (g) 215ab 193c 233a 204bc 190c 10.0 * ***

Kidney fat weight (g) 412 333 339 579 317 80.0 NS ***

Kidney weight (g) 105 115 121 117 130 7.0 NS ***

Liver weight (g) 624c 693bc 774ab 709abc 792a 31.0 ** ***

Lungs and trachea weight (g) 626 625 618 638 559 53.0 NS *

Mesenteric fat weight (g) 765 732 1015 1016 583 138.0 NS **

Spleen weight (g) 71 79 70 80 81 4.0 NS ***

Testes weight (g) 332a 281ab 400a 400a 279b 27.0 *** ***

‘a, b, c’ in the same row means a significant difference according to the indicated level of significance.NS: non-significant.

and fast

3c

fiTsr(vhL(braaCc

nttltTLfcMaAcl

bct

a The covariate was fast weight for all variables except for final weight* P < 0.05.

** P < 0.01.*** P < 0.001.

.3. Live weight, carcass weight and non-carcassomponent weights

The differences between the five genotypes for birth,nal live and slaughter weights are presented in Table 2.he results show final and slaughter weights wereignificantly affected by genotype. Charollais × Awassiam lambs had the highest slaughter weight value58.35 ± 3.63 kg) while Awassi ram lambs had the lowestalue (40.49 ± 3.63 kg). Similarly, the F1 crossbred lambsad a greater slaughter weight than the backcrossed lambs.eymaster (1987), Hill et al. (1993) and Abdullah et al.2003) reported no significant differences between cross-red and purebred lambs in birth weight. The presentesults also agreed with the results found by Hassan etl. (1996). They found that final weight was significantlyffected by genotype and that the first cross lambs (1/2hios–1/2 Ossimi) had a higher final weight than the back-rossed lambs (3/4 Chios–1/4 Ossimi).

Both hot and cold carcass weights (Table 2) were sig-ificantly affected by the lambs’ genotypes when adjustedo slaughter weight. Ram lambs of the CA genotype hadhe highest hot and cold carcass weights while Awassi ramambs had the lowest values. Solomon et al. (1980) reportedhat the breed of lamb significantly affected carcass weight.hey compared the carcass weight of 1/2 Suffolk, 1/4 Finnshandrace and 1/4 South down (Su × F × So) with 3/4 Suf-olk and 1/4 Rambouillet (Su × R) and found that Su × Rarcasses were always heavier than Su × F × So carcasses.oreover, Esenbuga et al. (2001) studied the carcass char-

cteristics of Awassi (A), Red Karaman (R), Tushin (T) andwassi × Tushin (A × T) lambs and found that A × T and Rarcasses had heavier cold weights than T and A genotype

ambs.

Dressing-out percentage was also found to be affectedy the lamb’s genotype (Table 2) with CA having signifi-antly greater values than Awassi. Our results agree withhose reported by several previous studies (Kremer et al.,

weight the covariate was birth weight.

2004; Sanudo et al., 1997). However, the present valuesdid not agree with those found by Macit et al. (2001) whenthey reported that the dressing-out percentage did not dif-fer significantly between Awassi, Morkaraman and Tushinbreeds.

The results for the non-carcass component weights arealso presented in Table 2. Only heart, liver and testesweights components were significantly different betweenlambs of the five genotypes, when each characteristic wasadjusted to slaughter weight. All the other componentsweights did not differ significantly between genotypes.These components are heart fat, kidney fat, kidney, lungsand trachea, mesenteric fat and spleen. Abdullah et al.(2003) found that heart, liver and testes weights differedsignificantly between CA, AR and Awassi genotype lambs.They found that RA genotype lambs had the heaviest heartand testes weights, while CA lambs had the heaviest liverweight. Pure Awassi in the same study had the light-est heart, liver and testes weights. Kashan et al. (2005)reported that heart and liver weights were affected sig-nificantly by the lamb’s genotype. Hassan et al. (1996)reported that lamb’s breed does not significantly affectkidney fat. Stanford et al. (1998) reported that breed ofthe dam affects significantly kidney fat, this result wasfound when they compared Finnish Landrace, Romanovand White Romanov.

3.4. Carcass cuts percentages and linear measurements

The results of carcass cuts percentages and linearmeasurements are presented in Table 3. Tail fat percent-ages were significantly affected by genotype (P < 0.001).Awassi ram lambs had the highest tail percentage. The

data shows that the tail fat weight was increased anddoubled in the backcrossed genotype (ACA and ARA) com-pared with the F1 crosses (F1CA and F1RA), but bothstill much lower in their tail fat than the pure Awassibreed.

172 A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175

Table 3Least-squares means of carcass data of the male Awassi and crossbred lambs.

Item Breed S.E. Significance

CA ACA RA ARA Awassi Breed Cova

Shoulders%b 41.16ab 39.62b 43. 29a 41.40ab 39.29b 0.94 * *

Racks%b 10.22a 10.28a 10.98a 10.53a 9.03b 0.34 ** **

Loins%b 11.55 10.67 10.89 9.64 9.66 0.58 NS NSLegs%b 34.31 33.17 32.87 34.43 32.98 0.81 NS NSTail%b 1.63b 2.62b 1.25b 2.33b 7.13a 0.63 *** ***

Body length (LB) (cm) 118.67a 109.33b 118.50a 108.50b 105.50b 2.21 *** –Leg length (T) (cm) 23.25 21.85 23.17 23.17 21.30 0.62 0.08 –Gigot width (G) (cm) 21.67a 20.05ab 21.00a 18.25bc 16.67c 0.85 ** –Width behind shoulder (WTH) (cm) 18.33a 17.41ab 19.16a 15.67bc 14.50c 0.86 ** –Maximum shoulder width (WF) (cm) 21.00a 20.08ab 21.08a 17.80bc 16.17c 1.00 ** –Eye muscle width (A) (mm) 66.92 65.67 67.17 62.17 59.58 2.21 NS –Eye muscle depth (B) (mm) 34.50a 30.42abc 32.25ab 28.92bc 25.75c 1.72 * –A:B ratio 2.00b 2.20ab 2.10ab 2.20ab 2.30a 0.10 * –Fat depth (C) (mm) 4.21 6.00 5.42 5.42 5.58 1.08 NS –Rib fat depth (J) (mm) 9.75 6.17 8.25 8.33 7.00 1.00 NS –Leg fat depth (L3) (mm) 13.33 10.58 10.41 11.58 12.08 2.00 NS –Shoulder fat depth (S2) (mm) 7.50a 5.60a 5.50a 5.66a 3.25b 0.87 * –Tissue depth (GR) (mm) 22.67a 17.17bc 20.00ab 18.33abc 14.92c 1.70 * –

‘a, b, c’ in the same row means a significant difference according to the indicated level of significance.NS: non-significant.

a The covariate was cold carcass weight for all cuts percentages.

b As a percent of cold carcass weight.* P < 0.05.

** P < 0.01.*** P < 0.001.

Both leg and loin percentages were not found to beaffected by genotype. Rack cut percentages differed signifi-cantly between genotypes (P < 0.01) with Awassi genotypehaving the lowest rack percentage (9.03 ± 0.34%). All othergenotypes did not differ significantly from each other. Theshoulder cut percentages differed (P < 0.05) between thefive genotypes with RA genotype having the higher per-centage (43.29 ± 0.94%) while the variation between theother genotypes was not significant. Stanford et al. (1998)studied the effect of crossbreeding on lamb carcass charac-teristics and found that genotype did not affect loin weightsignificantly. Szczepanski et al. (2001) found that legweight and percentage did not differ significantly betweenBlackhead sheep and F1 (Blackhead ewes × Romanowskasheep rams). The present results on the shoulder cut per-centage agreed with Hassan et al. (1996) and Stanfordet al. (1998). Kashan et al. (2005) compared the carcasstraits of two fat-tailed breeds (Chaal and Zandi) and theircrosses with rams of a tailed breed (Zel). They found thatthe average weight of the shoulder, brisket and loin washigher in crossbred than in pure breed lambs. Fahmy (1997)reported that Romanov sheep carcasses had a higher pro-portion of shoulder and a lower proportion of loin andleg than Booroola-DLS sheep. Güney (1990) found shoul-ders, loins and legs differed significant between breeds.Momani Shaker et al. (2002) found that shoulder weightand percentage was significantly different between geno-types with Awassi × Romanov crosses having the highestweight and percentage while pure Awassi had the lowest

values. Fat tail weight and percentage was the highest forthe pure Awassi genotype lambs. Leg and loin percentagewas the highest for Awassi × Charollais genotype lambs,while Awassi × Romanov lambs had the highest rack per-centage.

Carcasses lengths (LB) were significantly affected bygenotype, where CA and RA ram lambs had the longestcarcasses (118.67 ± 2.21, 118.50 ± 2.21 cm), respectively,while a length of 109.33 ± 2.21, 108.50 ± 2.21 and105.50 ± 2.21 cm was recorded for ACA, ARA, and Awassiram lambs, respectively. Length of hind legs, on the con-trary, was not significantly affected by genotypes. Widthsat the gigot (G), widths behind the shoulders (WTH)and maximum shoulder widths (WF) were significantlyaffected by genotypes. The highest width at the gigotwas recorded for CA ram lambs (21.67 ± 0.85 cm); how-ever, it did not differ significantly from ACA and RA ramlambs. Awassi genotype had the lowest (G) measurement(16.67 ± 0.85 cm). Width behind the shoulders (WTH) andmaximum shoulder width (WF) followed the same trend of(G) measurement. CA ram lambs had 18.33 ± 0.86 cm WTHand 21.0 ± 1.0 cm WF, while Awassi had 14.50 ± 0.86 cmWTH and 16.17 ± 1.0 cm WF.

Holloway et al. (1994) reported longer carcasses inAwassi crosses at a constant carcass weight. Macit etal. (2001) compared LB, G and some other carcass lin-ear measurements between Awassi, Morkaraman andTushin breeds. They found that width at the gigot is sig-nificantly affected by genotype (20.3 ± 0.35, 22.1 ± 0.35and 20.13 ± 0.39 cm for Awassi, Morkaraman and Tushin,respectively). On the contrary, they found that LB is notaffected by genotype, which disagreed with the presentresults and with the results found by Sanudo et al. (1997)on LB measurements and other carcass linear measure-

ments. Momani Shaker et al. (2002) reported that diagonalbody length was affected by the lamb’s genotype andwas the highest for Awassi × Romanov lambs (106 cm)and the lowest for pure Awassi lambs (98.58 cm) whileAwassi × Charollais lambs were intermediate (102.5 cm).

A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175 173

Table 4Least-square means of dissected leg tissues of the male Awassi and crossbred lambs.

Item Breed Significance

CA ACA RA ARA Awassi S.E. Breed Cova

Leg weight (g) 4766.0 4049.0 4398.0 3946.0 3685.0 303.0 NS **

Five large muscles weight (g) 1596.68 1290.04 1462.60 1275.33 1171.31 112.32 NS *

Femur bone weight (g) 247.063 212.44 241.46 203.38 182.07 14.50 NS NSFemur bone length (cm) 19.13a 18.33ab 19.52a 18.38ab 17.52b 0.43 * –Femur bone diameter (cm) 7.41a 6.68b 7.31a 6.56b 6.40b 0.20 *** –Tibia bone weight (g) 197.89 173.53 204.44 184.68 150.77 15.66 NS NSTibia bone length (cm) 22.58a 20.35b 22.93a 20.41b 20.00b 0.42 *** –Tibia bone diameter (cm) 6.50a 5.98bc 6.38ab 5.77cd 5.40d 0.15 *** –Intermuscular fat% 3.88 3.11 2.84 2.69 2.42 0.43 NS –Subcutaneous fat% 14.85 14.51 13.59 13.39 14.59 1.70 NS –Leg fat% 18.79 17.18 16.68 16.00 17.00 1.93 NS –Leg muscle% 60.49 58.81 60.23 59.42 55.69 1.66 NS –Leg bone% 18.32 21.52 20.20 22.53 20.93 1.00 0.07 –Muscularity index 0.50 0.45 0.46 0.43 0.44 0.016 0.07 –Muscle to bone ratio 3.32a 2.74b 2.98ab 2.69b 2.70b 0.14 * –Muscle to fat ratio 3.43 3.63 3.78 4.46 3.45 0.56 NS –

‘a, b, c’ in the same row means a significant difference according to the indicated level of significance.NS: non-significant.

a

Tlhca1pcs

gl2g(lgwtl

ssadwAwsa(oslws

The covariate was cold carcass weight for all variables.* P < 0.05.

** P < 0.01.*** P < 0.001.

he leg length in the same study was also affected by theamb’s genotype (P < 0.001) with Awassi × Romanov lambsaving the longer legs (22.82 cm). Solomon et al. (1980)ompared between (1) 1/2 Suffolk, 1/4 Finnish Landracend 1/4 Southdown (Su × F × So) and (2) 3/4 Suffolk and/4 Rambouillet (Su × R) to study the effect of breed onhysical, chemical and organoleptic properties of lamb car-asses. They found that width behind the shoulder wasignificantly affected by the lamb’s genotype.

The depth at the (GR) area was also affected byenotypes (P < 0.05); CA and RA carcasses of the ramambs had deeper GR tissues measurements (22.67 ± 1.70,0.00 ± 1.70 mm, respectively), while ACA and Awassienotypes had carcasses with shallower GR tissues17.17 ± 1.70, 14.92 ± 1.70 mm), respectively. ARA ramambs were not significantly different from the other fourenotypes (18.33 ± 1.70 mm). The shoulder fat depth (S2)as also significantly affected by genotype where CA geno-

ype had the greatest depth and Awassi genotype had theowest depth.

Abdullah et al. (2003) found that genotype did notignificantly affect GR, J and S2 measurements while itignificantly affected L3 measurements. These results dis-greed with the present results except in the case of J; theseisagreements may be a result of the differences in carcasseight, age, nutritional and measuring practice factors.nimals of that study were slaughtered at 180 days of ageith a final weight of 36 kg while in our study animals was

laughtered at approximately 240 days of age with an aver-ge final live weight of 55 kg. On the contrary, Stanford et al.1998) found that GR is significantly affected by the breed

f the dam, which agreed with the present results. Anothertudy by Hammell and Laforest (2000) reported that theamb’s breed affects the GR measurement significantly, this

as found by comparing the GR tissues in Dorset, Hamp-hire and Suffolk breeds. Holloway et al. (1994) compared

the carcasses of Awassi and Texel crossbred ram lambs andshowed that GR tissue depth was not differed among thegenotypes.

3.5. Dissected cuts

Data presented in Table 4 shows the least-squaresmeans for dissected leg tissues from the five genotypesafter being adjusted to the cold carcass weight. Femurbone length was significantly affected by genotype with RAgenotype having the longest femur bone (19.52 ± 0.43 cm)followed by CA genotype (19.13 ± 0.43 cm). Femur diame-ter and tibia length and diameter also differed significantlyamong genotypes. Tibia length did not differ between CAand RA genotypes but both were different from the othergenotypes. Femur and tibia diameters were both lower inpure Awassi ram lambs but higher in the CA genotype fol-lowed by the other crossbred ram lambs.

Muscle to bone ratio calculated for the leg cut wassignificantly different among the five genotypes. The CAlambs had the greatest ratio (3.32 ± 0.14) while all othergenotypes were not significantly different from each other.Kremer et al. (2004) reported that the meat to bone ratiowas higher for Texel × Corriedale crossbred lambs thanpure Corriedale lambs. The other leg tissue componentswere not significantly affected by genotype, but the calcu-lated muscularity index (which gives an indication for legmuscularity) approached the level of significance and thevalue was higher in the leg of CA, ACA and RA genotypescompared with ARA and Awassi ram lambs. The presentresults agree with Momani Shaker et al. (2002) who found

that leg weight of pure and crossbred Awassi ram lams didnot significantly differ from each other.

Dissected loin and rack data from the five differentgenotypes after being adjusted to the cold carcass weightare shown in Table 5. Meat to bone ratio was the only

174 A.Y. Abdullah et al. / Small Ruminant Research 94 (2010) 167–175

Table 5Least-square means of dissected loin and rack tissues of the male Awassi and crossbred lambs.

Item Breed Significance

CA ACA RA ARA Awassi S.E. Breed Cova

Loin weight (g) 1306.0 1351.0 1220.0 1301.0 1329.0 52.0 NS ***

Intermuscular fat% 16.79 12.04 13.31 12.22 9.56 2.07 NS –Subcutaneous fat% 12.10 11.01 12.33 13.93 11.01 1.72 NS –Loin fat% 28.88 23.00 25.62 22.56 20.57 2.96 NS –Loin muscle% 69.08 64.70 70.27 69.17 74.31 3.23 NS –Loin bone% 16.00 20.40 16.02 20.94 17.72 1.88 NS –Muscle to bone ratio 4.43a 3.29b 4.43a 3.59ab 4.29a 0.03 * –Muscle to fat ratio 2.51 3.07 2.89 4.22 3.90 0.70 NS –Rack weight (g) 1046.0 1026.0 1191.0 1239.0 1074.0 73.0 NS ***

Intermuscular fat% 26.11 18.59 23.22 21.12 19.22 3.58 NS –Subcutaneous fat% 9.94 10.93 9.88 11.61 10.20 1.07 NS –Rack fat% 36.03 29.49 33.07 32.68 29.39 3.53 NS –Rack muscle% 36.50 42.47 42.86 38.07 45.56 2.78 NS –Rack bone% 21.48 22.22 18.00 18.81 23.47 1.49 0.08 –Muscle to bone ratio 1.70 1.97 2.38 2.12 1.98 0.17 0.09 –Muscle to fat ratio 1.14 1.51 1.40 1.28 1.69 0.23 NS –

‘a, b, c’ in the same row means a significant difference according to the indicated level of significance.NS: non-significant.

a The covariate was cold carcass weight for all variables.* P < 0.05

*** P < 0.001.

Table 6Least-square means of meat chemical composition measured of the male Awassi and crossbred lambs.

Item Breed Significance

CA ACA RA ARA Awassi S.E. Breed

Dry matter % 27.49a 27.02a 27.27a 26.70ab 25.71b 0.38 *

Crude protein % (DM basis) 71.91 70.50 72.26 71.59 74.58 1.09 NSCrude protein % (as wet basis) 19.81 19.03 19.63 19.11 19.18 0.31 NSCrude fat % (DM basis) 22.61a 23.59a 21.30ab 21.41ab 19.58b 1.01 0.09Crude fat % (as wet basis) 6.22a 6.40a 5.82ab 5.71ab 5.03b 0.31 *

Ash % (DM basis) 3.32 3.31 3.67 3.64 3.48 0.15 NSAsh % (as wet basis) 0.91 0.89 1.00 0.98 0.89 0.04 NS

‘a, b, c’ in the same row means a significant difference (P < 0.05).NS: non-significant.

* P < 0.05.

variable affected by genotype (P < 0.05). All the other com-ponents of the loin tissue were not significantly affected bygenotype.

For loin weight, which was not affected by geno-type, the present results agree with Macit et al. (2001)who found that loin weight was not significantly dif-ferent between Awassi, Morkaraman and Tushin breeds.Rack composition was not affected by genotype. However,ARA genotype had numerically the highest rack weight(1239.0 ± 73.0 g).

3.6. Carcass chemical composition

Least-squares means of the carcass meat chemical com-position for male lambs of the five genotypes are presentedin Table 6. Dry matter percentage was significantly affectedby genotype. Another component that was significantly

affected by genotype was the crude fat percentage on a wetbasis. The lowest crude fat percentage was recorded for theAwassi genotype (5.03 ± 0.31%), while all other genotypesdid not differ from each other. This result indicates thatAwassi had the lowest intramuscular fat percentage. On the

contrary, crude protein and ash percentages on a wet basiswere not significantly affected by genotype. Even though,CA and RA had numerically a higher crude protein percentthan the other genotypes.

The present results agreed with that found by Hassanet al. (1996) that crude fat percentage was significantlyaffected by genotype. Kashan et al. (2005) reported that thepercentage of protein in the carcass of Zel × Zandi lambswas significantly higher than Zandi lambs.

4. Conclusion

Males outperformed females in all growth performancestages. F1 CA had a better growth performance than allgenotypes. B1 ACA growth was better than A and B1

ARA. Carcass composition was better in F1 than in Awassiprogeny while B1 progeny was intermediate. In conclusion,crossbreeding Awassi with Charollais improved growthperformance and carcass characteristics in terms of moremuscling.

minant

A

RttTRTAa

R

A

A

A

A

A

B

C

C

D

E

E

F

F

F

G

36, 85–89.

A.Y. Abdullah et al. / Small Ru

cknowledgements

The authors wish to thank the Deanship of Scientificesearch at Jordan University of Science and Technology forhe financial support of this project. Thanks are expressedo the personnel from Jordan University of Science andechnology for their technical assistance: M. Abu Ishmais,.I. Qudsieh, H.A. Ghozlan, S.K. Matarneh and I. Al-sukhni.he authors also wish to acknowledge the staff of thegricultural Center for Research and Production for theirssistance during animal slaughter.

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