Effect of Hot Carcass Weight on Fresh Loin, Ham, and Belly Quality from Pigs Sourced from a Commercial Processing Facility

The objective was to quantify the effect of HCW on pork primal quality of 7,684 pigs with carcass weights ranging from 53.2 to 129.6 kg. Carcass composition, subjective loin quality, and ham face color were collected on all carcasses. In-plant instrumental loin color and belly quality analyses were conducted on 52.0% and 47.5% of carcasses, respectively. Over 10% of the loins (n = 856) were selected for slice shear force (SSF) analysis. Coefficients of determination between traits were computed using the REG procedure of SAS and considered significant at P ≤ 0.05. As HCW increased, boneless loins were both darker and redder, evidenced by lesser L* (β₁ = -0.72, P < 0.001) and greater a* values (β₁ = 1.48, P < 0.001), however HCW only accounted for ≤ 0.80% of variability in loin L* and a* values. Similarly, loin subjective color score (β₁ = 1.45, P < 0.001) increased with carcass weight. Subjective marbling score was not affected by HCW (β₁ = -0.49, P = 0.06). After 20 d aging, HCW only explained 0.98% of variability in loin L* values (β₁ = -0.75, P < 0.01). Heavier carcasses had lower SSF values (β₁ = -0.77, P < 0.001) of loin chops, although HCW only explained 4.46% of variability in SSF. Although heavier carcasses produced loins that exhibited lower ultimate pH values (β₁ = -15.41, P < 0.001), HCW only explained 1.23% of the variability in ultimate loin pH. Interestingly, cook loss decreased (β₁ = -2.36, P < 0.001) as HCW increased, with HCW accounting for 5.60% of the variability in cook loss. Heavier carcasses resulted in darker ham face color, but HCW only accounted for 2.87% of variability in gluteus profundus L* values (β₁ = -0.97, P < 0.001) and 0.47% of variability in gluteus medius L* values (β₁ = -0.42, P < 0.001). Heavier carcasses produced thicker and firmer bellies, with HCW accounting for 37.81% of variability in belly thickness (β₁ = 76.41, P < 0.001) and 20.35% of variability in subjective flop score (β₁ = 11.01, P < 0.001). Overall, the proportion of variability in loin and ham quality explained by HCW was poor (≤ 5.60%) suggesting HCW is a poor predictor of primal quality of pigs within this weight range. However, the proportion of accounted variability may need to be revisited as market weights continue to get heavier. Supported by National Pork Board Grant #14-221.