Variation in lean distribution among steer carcasses of different breeds and crosses

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Abstract
Summary: Dissection data for 753 steer carcasses comprising 17 breed-type × feeding system groups were used to examine the distribution of lean between 14 standardized commercial joints. Breed types included Ayrshire, Friesian, Friesian × Ayrshire and crosses out of Friesians by Angus, Charolais, Hereford, Limousin, Simmental and South Devon sires. Most cattle were grown on cereal or grass/cereal systems of feeding. Group means for weight of lean in the side (half carcass) ranged from 60·0 to 85·2 kg with a pooled within-group S.D. of 7·81 kg.The increase in lean weight in each joint relative to that in the side was examined using the allometric equation. Pooled within-group growth coefficients (b values) indicated that relative lean tissue growth was lowest in the leg (hind shin) and rump (b = 0·84 ± 0·03 and 0·85 ± 0·03 respectively) and highest in the clod and sticking (b = 1·19 ±0·03). The result for the combined higher-priced joints was 0·95 ±0·01.The pooled growth coefficients were used to adjust the weight of lean in each joint to equal total lean weight in the side where this was legitimate. Statistically significant (P < 0·001) but relatively small differences were recorded between groups in the adjusted means for all joints tested. At equal total lean weight, Charolais × Friesian, Limousin × Friesian and Simmental ×; Friesian groups had the highest weight of lean in the combined higher-priced joints and the Ayrshire and Friesian × Ayrshire groups the lowest. The difference between the two extreme groups was 2·1 kg (for one side).