The influence of breed and sex on saleable beef yield

Abstract

Saleable beef yields from the carcasses of 38 Brahman crossbred bullocks, 42 Brahman crossbred females, 75 Hereford bullocks and 35 Hereford females were recorded in the boning room of an export abattoir. Regressions of saleable beef yield on 12th rib fat thickness and on rump P8 fat thickness were examined for breed and sex effects. Linear regression analysis showed that rump P8 fat thickness and 12th rib fat thickness predicted percentage yield of saleable beef with prediction errors at the mean (of the predictor variables) of 2.3 and 2.1 respectively. The inclusion of hot side weight with either fat thickness measurement in prediction equations did not significantly reduce the prediction errors. Either rump (P8) fat thickness or 12th rib fat thickness alone could be used to predict the weight of saleable beef, giving a prediction error of 12.4 kg, and the inclusion of hot side weight in these equations significantly reduced this error to 3.6 kg and 3.2 kg respectively. Quadratic analysis did not improve the accuracy of the prediction of percentage yield of saleable beef from either P8 alone or P8 plus hot side weight but it did reduce the prediction errors of saleable beef weight from P8 plus hot side weight to 3.5 kg. Regressions of percentage yield of saleable beef on 12th rib fat thickness did not vary significantly between Brahman crossbred bullocks and Brahman crossbred females, but they did between Hereford bullocks and Hereford females, and between each of the Hereford groups and the Brahmans. With increasing subcutaneous fat thickness Hereford females maintained a higher percentage of saleable beef than did the Hereford bullocks. Brahman crossbred cattle showed important yield advantages (1-3%) over Hereford cattle at all levels of fat thickness studied.