Breed and sex differences among equally mature sheep and goats 4. Carcass muscle, fat and bone

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Abstract
Males and females from Soay, Welsh Mountain, Southdown, Finnish Landrace, Jacob, Wiltshire Horn and Oxford Down sheep breeds and a breed of feral goats were slaughtered when proportionately 0·40, 0·52, 0·64 or 0·76 of mature live weight. On average, carcasses contained 583 g muscle, 243 g fat and 174 g bone per kg. Individual cuts (four commercially higher-valued and six lower-valued cuts of the shoulder, rib, loin and gigot joints) ranged from 375 to 670g muscle, 129 to 625 g fat and 0 to 294 g bone per kg.Allometric coefficients are given for 32 traits. The distribution of bone in the carcass joints changed little as animals matured but carcass muscle and fat distributions changed significantly.Breeds differed significantly in proportion of carcass muscle, fat and bone and also in their distribution. Welsh Mountain, Southdown, Wiltshire and Oxford Down all deposited carcass fat about three times more rapidly than did the Soay, goat, Finnish Landrace and Jacob. The Oxford Down had the lowest proportion of muscle (514 g/kg) and most fat (317 g/kg). The Southdown had least bone (148 g/kg) and the feral goat most muscle (662 g/kg). Southdown and Soay had the most muscle in commercially higher-valued cuts and Jacob and feral goat the least. Males had significantly more of their muscle in the neck and shoulder and significantly less in the gigot and flank.As breed size increased, proportion of carcass muscle and bone decreased and proportion of carcass fat increased. These breed regressions were attributed to the small but exceptionally lean feral Soay and goat breeds, rather than to a failure of genetic size-scaling. There were no significant trends with breed size among the domesticated breeds.