Live Animal and Carcass Measures for the Prediction of Carcass Traits in Lambs

Thirty-one grade Targhee ram lambs approximately 5½ months of age were assessed subjectively for conformation and slaughter grade. Objective measurements included shrunk live weight, flank thickness by caliper, fat thickness over the l. dorsi, l. dorsi depth, l. dorsi width (last three determined by surgery), seventh-rib probe and 12th-rib probe (skin surface to rib surface). After slaughter similar measures were recorded for the carcasses as well as percent of kidney and kidney fat, and percent and weight of closely trimmed retail cuts in the carcass and in the hind saddle. The results indicated that shrunk live weight was the most important single measure of weight of trimmed cuts (r=0.96), and seventh-rib probe for percent trimmed cuts (r=−.70) and for percent hind saddle (r=−.72). Multiple correlation equations for predicting various endpoints from live and from carcass measures are presented. The most practical equations for the prediction of percent trimmed cuts from live and from carcass measurements are as follows: Percent trimmed cuts=83.9-0.1122 (shrunk live weight, kg.) −0.454 (live conformation score; High Prime=15) −0.193 (7th-rib probe, mm.). R=0.77, S.E.=1.4%. Percent trimmed cuts=75.8-+0.414 (l. dorsi area, cm.2) −0.414 (left fat thickness over loin eye, mm.) −0.450 (left fat probe depth over 7th rib, mm.) −1.637 (percent kidney and kidney fat). R=0.88, S.E.=1.1%.