An update of the predicted lean yield equation for the Destron PG-100 optical grading probe.

In the swine industry, optical grading probes are used to collect measurements at one location on the carcass (i.e., the grading site); this information is used to predict carcass leanness with an established multiple regression equation. For the Destron PG-100 optical probe, the equation currently used by the industry was established using the 1992 Canadian National Cutout Study. The objective of the current study was to update the equation by utilizing a recent cutout study consisting of 337 pork carcasses (N = 188 for the calibration dataset; N = 149 for the validation dataset). A multiple regression equation was generated with the calibration dataset using stepwise techniques and the same parameters as the existing equation were used to fit the model. When the validation dataset was tested for prediction precision, the existing Destron predicted lean yield (LY) equation (R2 = 0.75) and the updated Destron predicted LY equation (R2 = 0.75) were strikingly similar in their abilities to predict carcass LY. However, when prediction accuracy was evaluated by separating carcasses into six 3% LY groupings, the existing Destron predicted LY equation correctly estimated LY 8.1% of the time, while the updated Destron predicted LY equation correctly estimated LY 47.7% of the time.