Cattle can experience heat stress during the summer months, which can lead to a decline in overall performance and an increase in responses indicative of stress. This study supplemented β-ligands (Ractopamine Hydrochloride; RAC and Lubabegron; LUB) during the summer months to evaluate the effect of β-ligand supplementation on cattle performance, carcass characteristics, rumination, mobility scores, and behavior. Three hundred sixty Angus crossbred steers were assigned to one of three treatments: Control (no β-ligand), RAC, or LUB, which was administered for the final 35 d of the finishing period. After a 4 d voluntary withdrawal period, cattle were slaughtered, and carcass characteristics were collected. Greater final body weight, average daily gain, feed efficiency, hot carcass weight, and ribeye area were observed in cattle supplemented with RAC and LUB compared to control cattle. The majority of the cattle had normal mobility scores, and mobility scores did not differ across treatments. No specific trends were detected between treatment steers for rumen parameters or behaviors related to feeding, drinking, standing, lying, and activity. In general, this study observed improved feedlot performance and carcass characteristics, with no impact on welfare behaviors or rumination parameters measured in β-ligand supplemented steers finished during the summer.

Read the full article in the Journal of Animal Science.