The use of physical measurements in live cattle to predict carcass composition

Abstract

Of 13 physical measurements made on live cattle, anal fold fat thickness measured with a hand caliper and fasted liveweight were the most accurate predictors of carcass composition, particularly when used together. Anal fold fat thickness plus fasted liveweight predicted the percentages (mean � s.e. of estimate) of side muscle (59.62 � 1.80), side bone (14.23 � 0.81) and side fat (23.58 � 2.18). Scanoprobe measurements made on live animals were correlated (P<0.01) with the actual carcass measurements as follows: fat thickness at the 10th rib, 0.50; fat thickness at the 12th rib, 0.69; muscle depth at the 10th rib, 0.56; muscle depth at the 12th rib, 0.66. Anal fold fat thickness, with a standard error of estimate of 2.22%, was a better predictor of percentage side muscle than the live Scanoprobe measurements, depth of M. longissimus at the 12th rib (3.44%) and depth of M. gluteus medius (3.61%). When used to measure the fat depth over M. longissimus at the 12th rib in live cattle, the standard errors of estimate of the Scanoprobe in predicting percentage side muscle and percentage side fat were not significantly different from those of anal fold fat thickness determined with the caliper. For the prediction of percentage side muscle the errors for Scanoprobe and caliper were 3.44 and 2.22, respectively; for the prediction of percentage side fat they were 3.79 and 3.12, respectively. Tuber coxae width, the most accurate of the linear skeletal measurements in predicting side bone percentage, was not as accurate as anal fold fat thickness (s.e. of estimate, 1.02 v. 0.89%).