Beyond lean meat percentage: Predicting primal cut proportions in pig carcasses using AutoFom III ultrasound and breed composition

Lean meat percentage (LMP) is the basis for European pig carcass classification, but carcasses with the same LMP and weight can differ in tissue composition and primal-cut proportions. This study evaluated how well yields of tissue types (lean, fat, bone) and primal cuts (forepart, loin, belly, hindpart) can be predicted from measurements by grading probes (Hennessy probe) compared to more advanced measurements from AutoFom III ultrasound scanner and breed composition The primary objective of LMP measurement is carcass classification, not prediction of primal cut proportions. Classification using AutoFom III serves a dual purpose: determining LMP for official carcass classification and prediction of primal cut sizes. Lean and fat percentages from registrations by manual slaughtering were highly negatively correlated to each other and well-predicted by LMP from grading probe and weight alone (marginal R²≈0.70 for lean, 0.68 for fat), improving to ∼0.79 and 0.76 with AutoFom III data. In contrast, primal cut proportions were poorly predicted by LMP and weight alone (R²≈0.09–0.13). Adding breed information raised R² slightly (to ∼0.11–0.20), and including both breed and AutoFom III data further improved R² to ∼0.16–0.30. Thus, LMP from grading probes and weight alone are insufficient to predict primal cut ratios; incorporating advanced ultrasound measurements and breed information provided additional predictive value.