COMPARISON OF 4 REAL-TIME ULTRASOUND SYSTEMS THAT PREDICT INTRAMUSCULAR FAT IN BEEF-CATTLE

Eighty-one crossbred steers were used to evaluate four commercially av ailable ultrasound systems that predict intramuscular fat. The softwar e systems represented included Animal Ultrasound Services, Inc., Ithac a, NY; CPEC, Oakley, KS; Critical Vision, Inc., Atlanta; GA (CVIS); an d Classic Ultrasound Equipment, 'Tequesta, FL. Systems were evaluated using marbling scores and percentage ether extractable fat of the long issimus muscle. Before statistical analyses, system predictions were c orrected for the respective system's average deviation between the pre diction and carcass measurement. The absolute difference between syste m prediction and percentage ether extract (EEADIFF) or marbling score (MADIFF) converted to ether extract by regression was analyzed with a model accounting for effects of system, technician within system, anim al, and animal x system. Steers with USDA marbling scores less than Sm all(00) were assigned to a low marbling class, and all others were ass igned to; a second class. Data were then analyzed with a subsequent mo del including marbling class. For EEADIFF in the first model, system, animal, and system x animal were significant (P < .001). For MADIFF, t echnician within system (P < .05) and all other effects (F < .001) wer e significant. In the second model, system x marbling class was signif icant (P < .05) for EEADIFF sind approached Significance for MADIFF (P = .17). Least squares means for EEADIFF indicated that the systems we re more precise measuring animals in the low marbling class. Finally, the CPEC and CVIS systems were the most precise for predicting intramu scular fat.