Prediction of pork belly fatness from the intact primal cut

Research was successfully undertaken to identify one or more non-invasive measuring sites on the primal belly which would predict belly fatness as well as or better than backfat depth at the grading site. Crossbred market weight gilts (n = 297) were slaughtered, dressed, graded, chilled and fabricated into primals according to commercial Canadian practice. A series of measurements were made on the primal both directly on the belly/loin cut, and from images of the cut. The ribbed, skinned and trimmed belly was ground for NIR compositional analysis. Both grade fat depth and one direct fat measurement (SFt) on the belly were equally strongly correlated with % fat in the belly (r = 0.86, P < 0.0001). Stepwise regression showed that calculated fat depths (Nolean 1 and 2) supplemented by a lean measurement (SLn) returned an R2 of 0.854 (RMSE 3.20), outperforming the grade site data (R2 = 0.762, RMSE 4.09). Prediction of belly fatness from measurements taken at the intersection of the belly/loin and belly/shoulder cuts was found to be poor.