PREDICTING THE YIELD AND COMPOSITION OF MATURE COW CARCASSES

Cow carcasses (n = 60) were selected based on conformation and externa l fat to develop more current and useful prediction equations for esti mating yield and composition. Adjusted preliminary yield grade was hig hly correlated to percentage of the carcass as fat (.91), percentage f at in the total lean (.89), and percentage fat in the lean trimmings ( .88) of carcasses from non-grain-fed mature cows. Equations for predic ting percentage of the carcass as chemical fat had higher R-2 values t han equations predicting other compositional end points. The ''best'' regression equation for predicting total yield (i.e., whole muscle cut s plus lean trimmings adjusted to 10% chemical fat) included hot carca ss weight (HCWT), adjusted preliminary yield grade (APYG), longissimus area (LMA), and marbling (MARB), with R-2 = .75 and residual standard deviation (RSD) = 2.47. A similar equation predicting total yield fro m unribbed carcass data included HCWT, APYG, and conformation (CONF) w ith R-2 = .69 and RSD = 3.11. These two equations were applied to a te st group of cow carcasses (n = 20), and the average difference between the actual and predicted total yield values from ribbed data and unri bbed data was .45 and .83% of HCWT; simple correlations between the ac tual and predicted values were .74 and .69, respectively. These equati ons contain relatively simple independent variables to identify and mo re nearly represent current industry processing practices than equatio ns previously available.