Wo. Herring et al., COMPARISON OF LIVE AND CARCASS EQUATIONS PREDICTING PERCENTAGE OF CUTABILITY, RETAIL PRODUCT WEIGHT, AND TRIMMABLE FAT IN BEEF-CATTLE, Journal of animal science, 72(5), 1994, pp. 1107-1118
Forty-four Hereford-sired steers were measured ultrasonically for back
fat and longissimus muscle area between the 12th and 13th ribs before
slaughter and visually appraised for fatness, overall muscling, and fr
ame. Carcass measurements associated with USDA yield and quality grade
s were measured and recorded. Carcasses were fabricated into closely t
rimmed, boneless subprimals at 1.27- and .32-cm fat trim levels. Cutab
ility percentage (percentage of retail cuts from the cold carcass weig
ht) and kilograms of retail product were defined three ways. The first
definition included only retail cuts from the round, loin, rib, and c
huck. The second included the above plus adjusted lean trim from the r
ound, loin, rib, and chuck, and, finally, total retail product from th
e entire carcass. Kilograms (TOTFAT) and percentage (PERFAT) of trimma
ble fat were also calculated. Stepwise regression procedures were used
for live and carcass trait model development predicting cutability pe
rcentages, kilograms of retail product, and trimmable fat. Fat measure
ments accounted for the largest portion of variation in cutability per
centage and PERFAT. Weight measurements accounted for the major source
s of variation in predicting kilograms of retail product arid TOTFAT.
Final models using live animal traits ranked the steers equally as wel
l for cutability percentages as the original USDA cutability equation
and stepwise, developed carcass equations(P > .10). Final models using
live animal or carcass equations ranked the animals equally for kilog
rams of retail product yield (P > .10).