Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 9, 1996
Publication Date: N/A
This experiment was conducted to compare the accuracy of electromagnetic scanning versus traditional carcass measures when predicting hot and cold fat-free lean in lambs. The prediction equations were developed using 120 wether and ewe cross-bred (Romanov x Dorset) lambs serially slaughtered at 3 week intervals (n=6) from 5 to 9 months of age. These equations were then validated on 66 lambs exhibiting the heavy muscling phenotype characteristic of the callipyge genotype. Fat-free lean, as determined by chemical analysis of the carcass, was defined as water + protein. Hot and cold carcasses were scanned at 2.5 MHz. Cold carcasses were scanned in an upright and side orientation. Peak of the electromagnetic scan curve (Peak) from cold upright carcasses was a better predictor of cold fat-free lean than hot carcass weight (HCW) (R**2=.96, RMSE=.48 kg versus R**2=.91, RMSE=.71 kg). Cold upright Peak and HCW were better predictors of cold fat-free lean than the USDA Yield Grade measurements of HCW and rib fat thickness (RFT) (R**2=.97, RMSE=.44 kg versus R**2=.93, RMSE=.63 kg). The same conclusion can be drawn when comparing the equations hot Peak and HCW to the above carcass measures for predicting hot fat-free lean (R**2=.95, RMSE=.54 kg versus R**2=.93, RMSE=.66 kg). When validated on a heavy muscled population, the variables of Peak and HCW were a more robust predictor of fat-free lean than the equation HCW + RFT (R**2=.96, RMSE=.49 kg versus R**2=.95, RMSE=.57 kg) for carcasses scanned cold in the upright orientation. This trend was also found for the side orientation and for carcasses scanned hot. These data indicate that electromagnetic scanning is a more accurate, robust predictor of fat-free lean in lamb carcasses than traditional carcass measures.