How well do bacon grade schedules reflect carcass composition?

Most bacon carcasses in Britain are measured, within the national Pig Carcase Classification Scheme operated by the Meat and Livestock Commission (MLC), for P2 fat thickness, shoulder and loin fat thicknesses and carcass length. Bacon curers use these measurements to define the grading schedules most appropriate to their buying requirements. There is debate about the value of mid-line fat measurements and length as indicators of carcass quality. The scientific evidence indicates that mid-line measurements are less precise predictors of carcass lean content than P2, and that the mid-line loin measurement is superior to the mid-line shoulder measurement.However, it is argued that the mid-line measurements may have special regional value: eg as predictors of carcass lean content in individual joints. The analysis reported uses a computer model (PIGRADER) to examine overall lean in carcass, the composition of individual joints and joint proportions for alternative grading schedules.