CHANGES IN PRIMAL CUTS WITH INCREASING CARCASS WEIGHT IN LARGE AND SMALL CATTLE

Carcasses from steers which had been fed to one of five within-breed slaughter weights, ranging from 363 to 544 kg for 74 small-framed Angus and from 454 to 612 kg for 71 Holsteins, were separated into wholesale cuts trimmed to 1 cm of outside fat. At the same carcass weight, Holsteins contained more (P < 0.05) of each of the trimmed chuck, rib, loin and round primal cuts. When carcass weight without, rather than with, kidney and KPH (kidney, pelvic and heart) fat was used as the predictor variable, each kilogram increase in carcass weight contained more of each of the trimmed primal cuts and the differences between Holstein and Angus carcasses were larger. Percentage primal cuts declined at a decreasing rate with increasing weight. Chilled carcass weight and fat thickness explained 70.6 and 61.8% of the variation in percentage combined primal cuts and round, respectively. Only from 20 to 27% of the variation in percentage chuck, rib and loin was explained by the best (minimum Sy–x and number of predictors) equations. Key words: Cattle, carcass, primal cuts, weight, mature size