ELECTROMAGNETIC SCANNING OF BEEF QUARTERS TO PREDICT CARCASS AND PRIMAL LEAN CONTENT

To study the use of electromagnetic scanning in prediction of lean con tent in beef carcasses and cuts, 100 beef cattle (60 steers and 40 hei fers), representing a broad range in external fat thickness (.1 to 2.9 cm) and live weight (414 to 742 kg), were selected. Chilled right sid es were divided into streamlined (foreshank, brisket, and ventral plat e removed) forequarters (FQ) and full hindquarters (Hand) and scanned. Primal rounds, loins, ribs, and chucks were fabricated from the right side, scanned, and physically separated into lean, fat, and bone. Pre diction equations for dissected lean content and percentage of lean in cluded the peak of the electromagnetic scan response curve (obtained f rom scanning the HQ or FQ), length, temperature and weight of the scan ned cut, and fat thickness at the 12th rib. Using the coefficient of d etermination, root mean square error, and Mallows' Cp statistic, the b est model for each dependent variable (weight and percentage of lean) that included up to five independent variables was selected. Predictio n equations for the HQ or FQ of steers accounted for 84 to 93% of the variation in lean weight of beef sides and quarters and 71 to 93% of p rimals. Sixty-one to 75% of the variation in percentage of lean in sid es and quarters and 48 to 65% of primals was also explained. Similar r esults were obtained for heifer carcasses. Predicting percentage of le an in any scanned cut, rather than weight of lean, accounted for less of the variation. Weight and fat thickness contributed significantly w hen predicting percentage of lean. These data indicate that electromag netic scanning is capable of objectively measuring lean content in bee f quarters and primals.