A comparative study on growth, body composition and carcass tissue distribution in Omani sheep and goats
Mahgoub, O.; Lodge, G.A.
Journal of Agricultural Science 131(3): 329-339
ISSN/ISBN: 0021-8596 DOI: 10.1017/s0021859698005887
Growth, body composition and distribution of carcass tissues were compared in Omani sheep and goats. Animals had ad libitum access to Rhodes-grass hay (8 % CP) and a concentrate diet (16 % CP) from weaning until slaughter. The two species had similar birth weights but sheep had higher preweaning (181 g/day), postweaning (175 g/day) and overall (179 g/day) growth rates than goats (120, 102 and 111 g/day, respectively) and thus they reached slaughter weights earlier. Sheep had higher slaughter weight (22.26 kg), empty body weight (20.39 kg), hot carcass weight (12.48 kg) and dressing out percentage (55-94 %) than goats (21.17, 18.82, 11.48 kg and 53.97 %, respectively). Sheep also had higher proportions of skin, liver and lungs and trachea (P < 0.01) than goats, which had higher proportions of head, feet and gut contents. As proportions of carcass weight, sheep had higher fat (25.08 %) but lower muscle content (57.24 %) than goats (15.72 and 65.88 %, respectively). There were no significant differences between the two species in proportion of carcass bone (13.76 and 14.17 %). These effects resulted in sheep having a lower muscle: bone ratio (4.19 and 4.68) and higher fat: muscle ratio (0.44 and 0.24). Sheep had higher proportions of non-carcass, carcass and total body fat in the empty body weight (EBW) than goats. However, sheep had less non-carcass but more carcass fat than goats when fats were expressed as proportions of total body fat. Sheep had higher proportions of muscles in the proximal hind limb, distal hind limb (P < 0.01), around the spinal column, connecting forelimb to thorax and high-priced muscle group (P < 0.05), but lower proportions of muscles in the abdominal wall, proximal forelimb (P < 0.05), distal forelimb (P < 0.01), connecting neck to forelimb, intrinsic muscles of neck and thorax (P < 0.05) and total forequarter muscles (P < 0.01) than goats. As proportions in carcass bone, sheep had higher axial skeleton (P < 0.05) but lower forelimb than goats. Among species/sex/slaughter weight groups, castrated male and female goats had the lowest growth rates. Castrates and female sheep, particularly at heavier liveweights, had higher carcass and non-carcass fat contents than intact males and goats of all sexes. Although Omani goats produced leaner carcasses and had higher proportions of some non-carcass offals than Omani sheep, they had slower growth rates and a less attractive muscle distribution. This may negatively affect their potential for large scale meat production under Omani conditions.