ESTIMATES OF THE CONTENT AND DEPOSITION OF NUTRIENTS IN THE CARCASS AND EMPTY BODY OF GROWING CATTLE

The fat and protein content of the carcass and empty body is decisive for the derivation of the requirement and utilization of energy and pr otein. The usual in vivo and post mortem methods involve a great deal of work and cost. In this study, the content of far and protein in the carcass and empty body was estimated by statistical models of the che mical composition of different cuts. Data on complete dissections of 5 4 bulls, 45 heifers and 45 steers were used for regression analysis. T he mass of fat in the different cuts (except fillet and shins) was hig hly correlated with the mass of fat in the carcass (R(2) = 91-97 %, de viation = 3.2-5.7 kg). The correlation for the empty body (R(2) = 81-9 3 %, deviation = 8.8-14.1 kg) was rather low. For the estimation of pr otein in the carcass, all cuts were equally suitable (R(2) = 91-97 %, deviation = 2.4-4.6 kg). The correlation between the mass of protein i n the cuts and the protein in the empty body was higher than for the m ass of fat (R(2) = 89-97 %, deviation = 3.7-7.2 kg). The combination o f different cuts improved the precision of the estimation of the mass of fat and protein in the carcass and empty body. The different combin ations of fore ribs, best ribs, flatribs, shoulder or brisket resulted in r-squares of about 98 % and a deviation between 3.2 and 3.8 kg for estimating the mass of fat in the carcass. For the estimation of the mass of protein in the carcass, r-quares of 97-99 % and deviations of 1.6-2.4 kg were investigated. The multiple-regression equations for th e estimation of the mass of fat in the empty body resulted in an r-squ are of 91 % and a deviation of 9.5 kg. The mass of protein in the empt y body and in the different cuts showed a distinctly higher correlatio n (R(2) = 96-98 %, deviation = 2.6-4.1 kg).