PSVII-19 Evaluation of Live and Carcass Performance of Holstein Steers Fed Lubabegron During the Finishing Period

Abstract

Abstract The objective of this study was to evaluate the effect of duration of lubabegron supplementation on live and carcass performance of Holstein steers. Holstein steers (n = 330) were enrolled in a feeding program supplementing lubabegron daily into a total mixed ration (TMR) at 3.2 g/ton for 0 (control) 28, 56, or 84 d. Steers were stratified by initial body weight (BW = 538 ± 37 kg) and then randomly assigned to treatments and pens. There were 8 pens total with approximately 40 head per pen. A GrowSafe feed intake recording system was used for the duration of the study to collect daily feed intake and feeding behavior on individual animals. Samples of premix were taken weekly for treatments to ensure nutrient requirements were being met and lubabegron concentration was accurate. Prior to departure from the feedlot and immediately upon arrival at the harvest facility, mobility of all animals was assessed. Individual IDs were matched with carcass identification and used throughout the harvest process to ensure the integrity of individual data. Carcasses were chilled for 48 hours and then went through USDA quality and yield grading protocols. Cattle fed lubabegron for 28 and 56 d had the greatest (P ≤ 0.01) average daily gain, total gain, as well as the least feed to gain ratio (P = 0.01) as compared with control steers and those fed lubabegron for 84 d. Conversely, control steers had the greatest (P < 0.05) feed-to-gain ratio. No differences (P ≥ 0.08) were observed between supplementation time for initial body weight, final body weight, and dry matter intake. Additionally, mobility scores were not different among supplementation protocols, neither at the feed yard, nor the harvest facility (P ≥ 0.64). Steers within the 28 d and 56 d treatments had among the greatest (P = 0.02) hot carcass weight. Ribeye area was increased (P = 0.01) by at least 3.87 cm2, when the cattle were fed lubabegron for any period of time. Cattle fed lubabegron for 56 and 84 d had an increased (P = 0.01) dressing percentage compared with 28 d and controls. While overall marbling scores were decreased (P = 0.04), the percentage of carcasses receiving USDA Prime, Choice, or Select quality grades were not different for animals receiving supplementation (P ≥ 0.31). The data suggest that lubabegron can positively influence live growth attributes; thus, translating to increased carcass yield, without sacrificing animal mobility or carcass quality.