The relationship of pork carcass weight and leanness parameters in the Ontario commercial pork industry.

This study aimed to examine the correlation of carcass weight, fat depth, muscle depth, and predicted lean yield in commercial pigs. Data were collected on 850,819 pork carcasses from the same pork processing facility between October 2017 and September 2018. Hot carcass weight was reported following slaughter as a head-on weight; while fat and muscle depth were measured with a Destron PG-100 probe and used for the calculation of predicted lean yield based on the Canadian Lean Yield () equation [CLY (%) = 68.1863 - (0.7833 × fat depth) + (0.0689 × muscle depth) + (0.0080 × fat depth) - (0.0002 × muscle depth) + (0.0006 × fat depth × muscle depth)]. Descriptive statistics, regression equations including coefficients of determination, and Pearson product moment correlation coefficients (when assumptions for linearity were met) and Spearman's rank-order correlation coefficients (when assumptions for linearity were not met) were calculated for attributes using SigmaPlot, version 11 (Systat Software, Inc., San Jose, CA). Weak positive correlation was observed between hot carcass weight and fat depth ( = 0.289; < 0.0001), and between hot carcass weight and muscle depth ( = 0.176; < 0.0001). Weak negative correlations were observed between hot carcass weight and predicted lean yield ( = -0.235; < 0.0001), and between fat depth and muscle depth ( = -0.148; < 0.0001). Upon investigation of relationships between fat depth and predicted lean yield, and between muscle depth and predicted lean yield using scatter plots, it was determined that these relationships were not linear and therefore the assumptions of Pearson product moment correlation were not met. Thus, these relationships were expressed as nonlinear functions and Spearman's rank-order correlation coefficients were used. A strong negative correlation was observed between fat depth and predicted lean yield ( = -0.960; < 0.0001), and a moderate positive correlation was observed between muscle depth and predicted lean yield ( = 0.406; < 0.0001). Results from this dataset revealed that hot carcass weight was generally weakly correlated ( < |0.35|) with fat depth, muscle depth, and predicted lean yield. Therefore, it was concluded that there were no consistent weight thresholds where pigs were fatter or heavier muscled.