Effect of Ractopamine Hydrochloride on Growth Performance and Carcass Traits in Calf-Fed and Yearling Holstein Steers Fed to Slaughter

Five studies using 2,105 calf-fed and yearling Holstein steers were conducted to evaluate the effects of ractopamine hydrochloride (RAC) on performance and carcass characteristics when fed for the final 28 to 38 d of the finishing period. In 4 calf-fed Holstein studies, RAC was incorporated to achieve intakes of approximately 0 (control), 200, and 300 mg/steer daily. In the yearling Holstein study, RAC was fed at 0 or 200 mg/steer daily. Each study consisted of 4 to 14 pens/treatment with 4 to 72 steers/pen, depending on study site. In the 4 calf-fed Holstein studies, ADG was increased (P < 0.05) by 0.24 to 0.28 kg/d for RAC treatments compared with the control treatment. Feed efficiency was improved (P < 0.05) by 14.4% for steers fed RAC. Carcasses from calf-fed Holsteins fed RAC were 4.7 and 5.1 kg heavier (P < 0.05) and mean LM area was 1.8 and 2.8 cm2 larger (P < 0.05) for steers receiving 200 and 300 mg/steer daily compared with the control, respectively. In the yearling study, Holstein steers receiving RAC consumed more (P < 0.01) feed and gained 18.7% faster than control steers (P < 0.01). No differences (P > 0.05) were noted in any carcass trait measurements. These data demonstrate that RAC improves growth performance, hot carcass weight, and LM area in both calf-fed and yearling Holstein steers while having a minimal impact on quality grade.