274 - Comparison of Two Ultrasound Systems for Estimation of Carcass Attributes in Feedlot Steers

Sixty-eight (68) crossbred steers were evaluated using two real-time, B-mode ultrasound units to estimate final carcass attributes. The cattle were ultrasounded at the West Texas A&M research feedlot (Canyon, Texas) and carcass data was collected at the West Texas A&M Meats Laboratory (Canyon, Texas) or Tyson Fresh Meats (Amarillo, Texas). Objectives of the study were 1) to compare ultrasound live animal data to carcass attributes at harvest 2) to evaluate the performance differences between the ALOKA 500 (ALK) and the EVO ultrasound units All ultrasound images were captured by the same Ultrasound Guidelines Council (UGC) certified technician with images being processed at the UltraInsights Laboratory (Pierce, Colorado). The correlations between 12^th rib fat thickness of the carcass (FTC) and ultrasound (FTU) were 0.84 for the ALK and 0.85 for the EVO, with no differences being found between the two units (P = 0.15). Correlations between the 12-13^th rib carcass ribeye area (REAC) and ultrasound ribeye area (REAU) were 0.69 for the ALK and 0.66 for the EVO. There was no difference in REAU size between the two units. Carcass marbling score (MS) and ultrasound intramuscular fat (IMFU) correlations were 0.78 for the ALK and 0.84 for the EVO. The IMF data were found to be different between the two units, with the EVO measuring a mean IMFU value of 6.03 and the ALK a value of 5.26 with the change of 0.77 being different (P < 0.01). It is concluded that both ultrasound units performed favorably when predicting FTC and marbling score but were not highly correlated for REAU. It was found that the predictions between the two units on FT and REA were the same, though the EVO was higher on both. The IMFU values between the ALK and EVO were different, with the EVO again predicting higher values.