A.0. EL SIDDIK, AND S.A. BABIKER.

Institute of Animal Production University of Khartoum – Khartoum North

‘ P.0.Box 32 Sudan

SUMMARY

Finishing copkerels of Brown Hisex ( egg laying strain ) to 1.5 kg liveweight produced a carcase weighing about 1. 0 kg at a feed conversion ratio of 4.70. Cuts as breast, thigh and drum stick as well as muscle yield were significantly‘ (P < 001) greater in cockerels slaughtered at heavier than at lighter weight. Sales revenue was greater when cockerels were finished to 1. 5 kg liveweight than to a lighter weight of 1.0 kg. Selling on livewight base saved the costs of processing and gave more return than selling on carcase weigh! bases.

INTRODUCTION

In developing countries the production oi‘ meat especially that of poultry is low. FAO U987) estimates of poultry meat production in developing countries was 12000 Meteric Tonnes in the year i986 while that of Sudan was l6 Meteric Tonnes only. ln the year 1986 per capita meat consumption was l3.2 kg while that of poultry meat was 0. 72 kg (Min. of Anim. Resources Sudan, l986) which represented 5 % of the meat consumed.

 In the Sudan poultry meat is obtained from specialized broiler strains, spent hens and cockerels. The latter are reared under different managlement conditions and slaughtered at different weights. Recently, Babiker and Nasir (I984) indicated that cocketels from egg laying strains finished on broiler mash. performed better and yielded heavier caicases than those finished on chick mash. Egg laying strains slaughtered at older age of 14 weeks produced heavier carcases than those slaughtered at 7 and X weeks of aget Mikoltiscdk and Pour, 5980). Joint weight an-.1 carease yield were also found to increase an birds slaughtered at older than at younger age ( Letihe, I984). The eileet of slaughter \\€lgl1l on pesforinanee car- case characteristics, meat chemical composition and production economics 0t eockerels from red I-Iisex laying strains were evaluated in this study.

MATERIALS AND METHODS

 180 one – day old male chicks (_B_l_’OWn ffiisept egg laying strains)lwere used. Chicks were distributed into I2 pens =5cn’mt2:iritrig’equs1 weight and number. The pens were then randomly allocated to two slaughterweights which were l.0 and l.5 kg. Each slaughter weight'( treatment) comprised or sixipens. ‘ The two treatments were fed adlibiium on and the same ration ( Table 1) thro- ughout the experiment. Water was available all the times. Food intake was recorded daily and liveweight gain of each pen was taken weekly.

 When the specific target weight was attained birds wereindividually weighted after an overnight fast t‘ except for water l and slaughtered without stunning. Following scalding, plucking, washing and evisceration internal organs and head and shanks were weighed individually and expressed as percentage of slaughter weights. Eviscerated cai-cases were weighed, chilled for l2 h. at 4 c‘ and cold car- case weights were recorded. Five carcases wererandomly selected from each pen for cutting and dissection-    The breast, drumsticlt and thigh joints were removed and weighed. Each joint was then dissected into meat ( including skin, tendons and sub- cutaneous fat) and bone. Meat and bone were weighed individually and expresed as precentage of joint weight. The dissected joints meat was minced twice, thoroughly hand mixed and analysed for moisture, protein and fat contents according to the AOAC 1975). Data were subjected to student-t-test according to Snedeccr and Cochran (1961). ‘ .

RESULTS

Chick Performance : Cockerels performance data are given in Table 2. Although birds slaughtered at heavierweights ( Treatment ll) ate significantly (P < 0.001) more food, they gained significantly (P < 0.001) more than those slaughtered at lighter wights ( Treatment 1). Slight significant (P< 0.05) decrease in Feed conversion eflieiency with weight increase was observed. Mortality was low and similar in the two slaughter weights.

 from Treatment ll than those obtained from Treatment l. Muscle to bone ration and chilling loss were similar in the two treatments.

 Organ Proportion of Cockeris : _ Birds slaughtered at heavier weights ( Treatment 11) had significantly (P 0. 001) lighter heads and shanks, heart, gizzard and liver than those slaughtered at lighter weights ( Treatment 1). Total viscera weight was significantly heaver (P 0.001) in cockerels from Treatment ll than those from Treatment 1.

 in fat found in meat from Treatment 11 than in Treatment 1. Protein and ash were similar in the two treatment groups. _ V I Balance of Cost and Revenue : ‘ ‘ As Seen in Table 6 birds in Treatment 11 gained rnore revenue than those in Treatment 1. The amount of gain was greater when selling was on liveweight base than on carcase weight.

DISCUSSION

Birds in treatment H took 120 days to attain a slaughter weight of about 1.5 kg than those in Treatment 1 which were slaughtered at an age of 90 days and a liveweight of 1.0 kg. This explains the significant increaee in food in take observed in the former group. Age difference also explains the decrease in food conversion efiiciency observed in Treaiment 11 ( Ki-ishnappa et ai, 1976 and Gonzalez,1986).    Heavier liveweight effect was clearly seen in the increase in carcase weight, dressing precentage and muscle yield which agreed, with the findings of Mikola- sek and Pour (I980) , Najib et al, (1985) lkhlas Nour (I985) and Babiker and Nasir (l-984). l The jointyield in Treatment ll was greater than in Treatment 1 due to differences in carcase weight ( Table3). The increase in weight of head and shanks, heart and gizzard in Treatment I , with age, was in accord with findings of Haseler (I968) and Crawly et al (1980) and can be attributed to the growth diffcerential of tissues; with progress of age, the liveweight, increases and consequently the proportions of early maturing tissues and organs decrease. , The increase in fat deposition, with age and weight increase , could explain the significant increase in extractable fat in Treatment lland the decrease in muscle moisture.

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