Authors : A. Plascencia , N.G. Torrentera and R.A. Zinn
Abstract: One hundred forty crossbred steers (373�22 kg) were used in a randomized complete block design experiment (14 pens, 10 steers/pen) to evaluate the influence of supplementation of a steam-rolled wheat-based finishing diet with 6 mg kg 1 (as-fed basis) zilpaterol during the final 6 weeks of the finishing period on growth performance and carcass characteristics. Supplemental zilpaterol did not influence (p>0.20) DM intake (8.55 vs. 8.45 kg day 1), but enhanced (p<0.01) ADG (33%, 1.45 vs. 1.93 kg day 1) and feed efficiency (26%, 5.90 vs. 4.38). Based on observed NE intake, ADG of the non-supplemented steers was 99% of expected. In contrast, with zilpaterol supplemented steers ADG was 24% greater (p<0.01) then expected. Zilpaterol supplementation increased carcass weight (4.0%, p<0.01), dressing percentage (3.9%, p<0.01) and fat thickness (26%, p<0.05) and reduced KPH (14% p>0.05), but did not influence (p>0.20) LM area or marbling score. Adjusting to a constant carcass weight, zilpaterol supplementation increased gross (bone- and trim-in) primal cuts (1.7%, p<0.01), boneless closely trimmed primal cuts (2.9%, p<0.05) and boneless closely trimmed retail cuts (3.2%, p<0.10).
A. Plascencia , N.G. Torrentera and R.A. Zinn , 2008. Influence of the β-Agonist, Zilpaterol, on Growth Performance and Carcass Characteristics of Feedlot Steers. Journal of Animal and Veterinary Advances, 7: 1257-1260.