Abstract:
Distribution patterns of subcutaneous fat, intermuscular fat, muscle and bone were examined in a total of 108 lamb carcasses from six genotypes (Dorset Horn and Border Leicester rams mated to Merino, Corriedale and Border Leicester x Merino first cross ewes), two sexes (wethers and ewes) and three slaughter weights (34,44 and 54 kg liveweight). The distribution of half-carcass components was based on five joints (hindlimb, loin, thorax, forelimb and flank) from the left side of each carcass. Muscle distribution was also assessed on the 10 standard muscle groups. The distribution of subcutaneous fat, intermuscular fat and muscle in the carcass was directly related to the total amounts of the respective tissues (P < 0.01) and was not affected by genotype or sex. Bone distribution was affected by sex and breed of dam, although it was suggested that the breed of dam effect was due to errors in halving the carcass. The sex effect was such that wethers had 2.8% more bone in the forelimb, while ewes had 1.9% more bone in the hindlimb, at the same total bone weight (P < 0.05). Growth coefficients for subcutaneous fat, intermuscular fat, muscle and bone all exhibited distoproximal growth gradients. _______________________ *Part II, Aust. J. Agric. Res., 30: 1207 (1979).