The accretion and distribution of carcass tissues in steers during growth between 9 and 15 months of age

Abstract

Carcass muscle, fat and bone weights, and distribution in 12 Brahman x Hereford steers between 9 and 15 months of age were obtained by carcass side dissection. The tissue proportions of liveweight and carcass weight at mean age 13 months, and the regression estimates of tissue accretion and distribution were compared. The carcass muscle and bone components of liveweight gain decreased by 18 and 24% respectively, and carcass fat increased by 64% when all tissues were compared to composition at 13 months of age. The tissue components relative to carcass weight gain followed the same pattern. The decrease in muscle and bone growth relative to liveweight gain was greater in the hindquarters. Whereas hindquarter muscle, fat and bone were 530, 570 and 450 g/kg respectively of carcass muscle, fat and bone at the mean age of slaughter, they were 500, 570 and 420 g/kg of the respective carcass tissue accretions between 9 and 15 months. The disproportionate decrease in muscle accretion between the carcass quarters was largely a result of differences in growth among the 26 heaviest carcass muscles.