Prediction of bone-in retail cuts and edible meat of crossbred lamb carcasses

Abstract

Multiple regression equations describing the percentage yield of bone-in retail cuts and edible meat were developed for lamb carcasses ranging in breed (lambs from Border Leicesterx Merino ewes sired by Suffolk, Southdown, Poll Dorset and Corriedale rams), sex (entire males, wethers and ewes) and carcass weight (12-25 kg). The regression equations first developed contained carcass weight as the sole predictor and these were compared with equations containing carcass weight and two additional predictors: fat depth over the 12th rib and percentage kidney and channel fat. Breed and sex, conformation score, carcass length and leg length were tested with carcass weight in separate analyses. The equations containing carcass weight and measures of fat status accounted for more of the variation in yield of retail cuts and edible meat and had lower residual standard deviations (RSD) than did equations containing the other variables. Fat depth, and percentage kidney and channel fat provided a similar degree of accuracy in predicting the percentage of retail cuts (RSD of 2.96 and 2.87 respectively) or edible meat (3.33 and 3.17 respectively). Inclusion of the quadratic terms had no significant effect on the values for RSD. The variation in fat status of 17 kg carcasses was such that the predicted yields of retail cuts or edible meat ranged from 65 to 71 % and from 49 to 55%, respectively. It was concluded that a lamb classification system need only provide objective information on carcass weight and kidney and channel fat to enable the industry to identify carcasses differing in economic value.