Differences in the Relation between Carcass Visual Scores and Composition in Heifers and Steers

Abstract

It is well recognised that heifers, which are the source of approximately 0.35 of all clean cattle slaughtered for beef in Britain, yield carcasses that are different from those of steers in several commercially important aspects: they are lighter, are scored fatter than steers and have poorer conformation. Live and carcass wholesale prices for heifers are, on average, lower than for steers.In the USA, studies have shown that yield grade equations, deveoped to predict the ‘cutability’ of carcasses, overestimate this in heifers compared with steers, ie. heifers yield less of the defined primal cuts than steers at the same levels of fat thickness over the rib, rib eye area, kidney + pelvic + heart fat proportion, and carcass weight (predictor variables). However, it has recently been shown that this bias is apparently the result of differences between the sexes in the relation between the fat depth measurement and the total amount of fat trim. In Britain, estimates of yield are based on visual scores of fatness and conformation, but there Is little information on the relations between carcass morphology and composition in the two sexes, differences in which may have important commercial implications.