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Abstract The objective of this study was to determine the economic benefit of implanting beef steers and including a beta-agonist in the finishing diet. To accomplish this, Hereford-cross steers (450 ± 15 kg) were assigned to one of three drylot pens based on initial body weight (BW) and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement 22.0% CP, 2.90 Mcal ME/kg dry matter (DM). The data were analyzed in SAS v9.4. Animals were evaluated on intake, growth, and performance measures during a 45-d feeding trial. Average daily gain (ADG) and hot carcass weight differed (P 0.05) between treatments with AND steers gaining 1.48 kg/d with a hot carcass weight of 394.8 kg, BAG steers gaining 1.28 kg/d with a hot carcass weight of 352.9 kg, and IMP steers gaining 1.26 kg/d with a hot carcass weight of 347.4 kg. The BAG treatment rendered decreased marbling scores than IMP and AND (P 0.05). It was concluded based on carcass quality data that there was no difference in the IMP and AND treatments, though the AND treatment had greater growth rates and feed conversion rates. Results of this trial are expected to indicate at what price point it becomes economically effective to finish animals using a beta-agonist in conjunction with a hormonal implant.
Robertson et al. (Wed,) studied this question.