Predicting pork carcass and primal lean content from electromagnetic scans

Fifty-four whole, pre-rigor, eviscerated carcasses (74.1±kg) were selected over a 5-week period to represent carcasses marketed to a Northwest Iowa packing plant during the fall season. Carcasses (spanning 40.7-65.2% carcass lean) were electromagnetically (EM) scanned before entering the chiller. Carcass right sides were fabricated and weights were recorded for each jowl, ham, loin, Boston butt, picnic shoulder, neckbone, sparerib, and belly. Each component was skinned and dissected into external fat, internal (seam) fat, bone, and lean with corresponding weights recorded. Regression equations were derived from points and areas taken from the EM scan curve. The best 5-variable equations were developed for total carcass lean (R(2)=0.9502; RMSE=1.31 kg), percentage carcass lean (R(2)=0.8789; RMSE=1.88%), ham lean (R(2)=0.8475; RMSE=0.755 kg), loin lean (R(2)=.8511; RMSE=0.781 kg), Boston butt lean (R(2)=.7251; RMSE=0.505 kg), picnic lean (R(2)=0.7387; RMSE=0.464 kg), and commodity, component carcass value (R(2)=0.9458; RMSE=$3.24).