PREDICTING BEEF CARCASS CUTABILITY

Analyses were conducted to develop and test the efficacy of beef carca ss cutability prediction equations. Data from 1,602 calf-fed steer car casses (Germplasm Utilization Project; GPU) were used to develop the e quations and an additional 1,160 calf-fed steer carcasses (Germplasm E valuation Project; GPE) were used to validate the equations. In both e xperimental groups, USDA yield grade ranged from < 1 to > 5 and the SD of yield grade was > .8 indicating a relatively large amount of varia tion in carcass cutability. Models were developed to predict boneless, totally trimmed retail product yield (RPYD), fat trim yield (FATYD), and bone yield (BONEYD) using 1) carcass traits, 2) carcass traits and wholesale rib dissection traits, 3) carcass traits and 9-10-11 rib di ssection traits, and 4) carcass traits and 9-10-11 rib dissection and chemical traits. For each dependent variable, the best single predicto r was a wholesale rib dissection trait, and the best higher order mode l contained at least one wholesale rib dissection trait. Equations dev eloped explained 87, 88, and 77% of the variation in RPYD, FATYD, and BONEYD, respectively. When validated against GPE carcasses, models dev eloped from GPU carcasses explained 74, 78, and 69% of the phenotypic variation and 96, 94, and 84% of the genetic variation in RPYD, FATYD, and BONEYD, respectively. Prediction of carcass cutability using carc ass and wholesale rib dissection traits should allow for rapid, precis e, and cost-effective assessment of variation in cutability.