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Individual muscles were dissected from the carcasses of 212 rams and ewes of the Romney and Southdown breeds and their cross in a comparative slaughter trial. Sample animals were slaughtered at birth and 1,6, 11, 16,25,41, and 80 weeks of age and at maturity. Allometric growth coefficients are presented for the individual muscles and for nine muscle groups, individual muscle growth being related to total muscle growth and coefficients being compared between breeds and between sexes. Coefficients differed significantly between breeds and between sexes for some muscles and muscle groups. The effect of different relative growth rates (and constants) on the proportions of the various muscles and muscle groups at selected total muscle weights is reported. The breed effects on individual muscle growth. although significant, tend to average out so that, where present, these differences result in minimal differences between breeds in the proportions of muscle in the different groups. The large differences in conformation noted by the meat trade between Romney and the Southdown-Southdown Romney cross are not reflected by a markedly better distribution of the more valuable muscles in the blockier Southdown type carcass. 115

The growth of the hot carcass and some non-carcass components of 212 rams and ewes of the Romney and Southdown breeds and their cross was obtained from a comparative slaughter trial. Samples were slaughtered at birth, at 1, 6, 11, 16, 25, 41, and 80 weeks of age, and at maturity. Allometric growth coefficients are presented relating component weight to starved body weight together with estimates of component weights for the different breeds and sexes at 5, 10, 20, 30, 40, and 55 kg live weight. The growth of the fat depots and the stomach (excluding the abomasum) was markedly faster than that of the starved body weight, and the growth of most of the reproductive tract was moderately faster. The remaining body parts grew at rates similar to, or slower than, starved body weight.

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