Prediction of composition traits of young Charolais bull carcasses using a morphometric method

The relationships among morphological traits and bovine carcass composition traits were analysed in order to select carcass measurements to derive equations for predicting muscle weight, percentage of muscle and muscle to bone ratio. The sample, constituted by 35 young Charolais bulls slaughtered at 18 months old, was homogeneous, e.g. half carcass weight = 225 ± 13.2 kg (standard deviation), carcass fat% = 6.4 ± 1.0, carcass muscle% = 74.58 ± 1.47, carcass bone% = 16.87 ± 0.83. Carcasses were weighed and a sub-group of carcass measurements was selected from the results of a principal component analysis, performed on 76 measurements taken from carcass photographs. The computation of the best combination of variables for prediction was based on the Mallows' Cp statistic and linear regression. The percentage of muscle was best predicted by only three carcass measurements with a relatively low value of fit (R(2) = 0.70). When carcass weight was added to the same measurements to obtain the best prediction for muscle weight, the fit was high (R(2) = 0.98). The prediction of muscle to bone ratio required nine variables and again the fit was high (R(2) = 0.90).