Prediction of lean content in the carcasses of beef cattle. II. From measurements of specific cuts

Abstract

Carcass data on 304 steers and 320 heifers from seven breed of dam groups were analyzed to test equations for predicting weight and proportion of lean content in beef carcasses from measurements of specific cuts. All dams were bred to Angus sires for first calving and to a Simmental sire for second and third calvings. Cattle by Angus sires were slaughtered at 10-mm backfat thickness evaluated ultrasonically; those by the Simmental sires at 7 mm. One side of each carcass was cut into eight cuts and separated into fat, lean and bone. Data were analyzed by multiple stepwise regression procedures. Prediction equations from each cut were obtained from the overall data and subpopulations by breed of sire, by sex and by breed of dam group. Cold-carcass weight accounted for the highest proportion of variation of lean weight in the side of the carcass, but it accounted for no more than 3% of the variation of proportion lean. Lean weight in hip and chuck, particularly in hip, was a most important predictor for estimating lean weight of the side. Total weights of each cut were also important predictors. Proportion lean in each cut alone was the strongest predictor of proportion lean in the carcass. Proportions of weights of cut in the carcass were also important predictors. Predictions of lean content (weight and proportion) in the carcass from dissected cuts of chuck and hip provided the most precise estimates. Average biases for breed of sire–degree of finish combinations, sex or breed of dam group were relatively small when an overall equation based on information from the hip was used. Key words: Beef, prediction of lean content, carcass, cuts, breed, sex