Computer tomography and ultrasound measurement as methods for the prediction of the body composition of lambs

In Austria, performance testing in sheep breeding is carried out either with computer tomography or ultrasonography. The aim of this study was to compare the two methods on a sample of 41 male lambs (19 Merino, 14 Suffolk, and 8 Texel). To estimate the actual composition of the animals, one-half of their carcass was dissected into muscle, fat and bone after slaughter. Total fat in the carcass ranged from 8.8 to 28.5%, while the muscle was between 49.5 and 67.4%. The correlations obtained between the actual fat in the carcass and fat content measured with computer tomography or ultrasonography was 0.88 and 0.72, respectively. Corresponding correlations for muscle content were 0.68 and 0.48, respectively. Computer tomography is more accurate in predicting the actual body composition, on the other hand, ultrasonography is a cheaper equipment with lower operating costs. The predictions for fat content were more accurate than muscle content in the present study. One can conclude from the two invasive methods that both are useful tools for the prediction of body composition of lambs in animal breeding.