Effects of Sex-Related Differences in External Fat Deposition on Subjective Carcass Fatness Evaluations—Steer versus Heifer

A cutability prediction equation derived from data on 129 steer and 80 heifer carcasses and based on the factors included in the USDA beef carcass yield grade equation, underestimated the cutability of steer carcasses by .19% and overestimated the cutability of heifer carcasses by .31%. However, this difference was essentially eliminated by substituting “carcass percentage of external fat trim” for “adjusted thickness of fat over the rib eye” in that equation. While the steer and heifer carcasses had similar patterns of fat deposition on their various parts, at the mean predicted cutability of the steers and heifers combined, heifer carcasses had greater (P<.05) percentages of external fat trim in 9 of 10 carcass areas than did steers. That difference was greatest for the fat trim from the cod or udder, chuck and rump, and least for the inside and outside round. Except for the outside round and flank, sex did not have a differential effect on fat deposition at different levels of predicted cutability. Heifers varied more in the amount of fat on their various parts than did steers, and subjective evaluations of the fatness of the various areas of the steer carcasses almost always had higher simple correlations with the corresponding actual percentages of external fat trim than did the heifer carcasses. It appears that any subjective carcass evaluation procedure aimed at eliminating the external fat trim sex-bias between steer and heifer carcasses would have to include an arbitrary adjustment reflecting that, by comparison with steer carcasses, heifer carcasses will be fatter than indicated by their appearance.