PSIX-27 Evaluation of real-time ultrasound to predict pre-harvest market endpoints in serial slaughtered British x Continental steers administered an E2+TBA implant treatment vs non-implanted controls

Abstract

Steers (n = 80; initial BW 271 ± 99) were serially scanned at 42-d intervals during a 378-d feeding period using an Aloka 500 device by a certified Ultrasound Guidelines Council (UGC) technician using real-time ultrasound. This included 10 separate ultrasound scanning sessions following the initial weight and ultrasound data taken on day minus 7 (one week prior to initial start date). Steers were randomly assigned to implant treatment (either implanted with Revalor XS or not) at day -7. Cattle were weighed and scanned for 12th-rib fat thickness (FTU), 12th-rib longissimus muscle area (LMAU), percentage intramuscular fat (%FATU), and rump fat thickness (RFU) to determine the ability of ultrasound to predict carcass grading outcomes at harvest. Scans were processed by CUP Lab technicians. Eight steers were harvested each 42 days. Carcasses were assessed 48h after harvest to determine 12th-rib fat thickness (FTC), 12th-rib longissimus muscle area (LMAC), and marbling score (MARB). Data were analyzed via Pearson correlation and linear regression to determine the relationship of ultrasound measures to carcass outcomes. Positive correlations (P < 0.01) between ultrasound measures taken the day before harvest and carcass measurements indicated strong relationships between FTU and FTC (r = 0.91), LMAU and LMAC (r = 0.93), and moderately strong relationships between %FATU and MARB (r = 0.76). Prediction equations were generated to estimate FTC = .0088 + (1.02585 x FTU), LMAC = 16.29720 + (0.77197 x LMAU) and MARB = 19.87510 + (5.19832 x %FATU). Results suggest real-time ultrasound data provides an effective tool to estimate carcass outcomes pre-harvest.