Predicting primal weight and primal yield in pork carcasses from a large-scale survey at major meat processing centers in Japan.

Pork primal weight and primal yield are important indicators for pig breeding, feeding management, commercial distribution systems, and meat processing. Here, we aimed to determine whether primal weight and primal yield could be predicted through non-destructive measurements of pork carcass traits. A total of 4397 carcasses (1958 gilts and 2439 barrows) from eight major meat processing centers were used, and the mean primal weight and primal yield were 56.0 kg and 73.9%, respectively. Significant sex differences were observed for all primal and carcass traits (P < 0.001), except for carcass weight. A maximum of 12 variables were examined, and primal weight was predicted with very high accuracy (R = 0.95, RMSE = 1.7, RPD = 3.0) using four variables. Primal yield was predicted with relatively good accuracy (R = 0.71, RMSE = 2.3, RPD = 1.4) using three variables, and these same variables were also effective for predicting primal weight. These prediction formulas were sufficiently accurate without accounting for the effect of sex. Overall, our results demonstrate that primal weight and primal yield can be accurately predicted using four variables, "carcass weight," "backfat thickness above M. gluteus medius," "spinous process length of 13th thoracic vertebra," and "length from 1st thoracic vertebra to backfat," without accounting for the effect of sex.