Evaluation of Factors Associated with the Composition of Pork Carcasses

Abstract

DATA collected from the physical separation of 70 half-carcasses and cutability measures from 250 carcasses were related to singular and combined linear measurements and to indicator cut analyses. With the exception of carcass weight, singular carcass measures were similarly related to percentages of separable lean and four lean cuts. Subcutaneous fat thickness measured at three locations opposite the longissimus muscle at the 10th rib (fat depth) was the single measurement which was most closely related to percentages of separable lean and four lean cuts. Carcass length and carcass weight were least indicative of changes in pork carcass composition. Comparisons of multiple regression equations in which measures of fat depth were used rather than backfat thickness as the fatness indicator revealed general increases (0.28 to 12.05%) in coefficients of determination. The inclusion of measures of both fat depth and backfat thickness in regression equations suggested little advantage over using the best singular measure for predicting percent separable lean, but increases of approximately six percent for predicting percent of four lean cuts. Equations which incorporated the linear measurement of carcass length, longissimus muscle area, backfat thickness and fat depth accounted for 78.58 and 73.65%, respectively, of the variation in percentages of separable lean and four lean cuts. Correlation data revealed only minor differences between ham, loin and belly sections in their relationships to separable components of the half-carcass. Attempts to identify an indicator cut from the shoulder (jowl, picnic shoulder or Boston butt) for predictive purposes were not successful. A regression equation combining separable tissue percentages for a small section derived from the loin (loin section E) accounted for 83.51% of the variation in separable lean content of the half-carcass.