Effect of Two β-Adrenergic Agonists on Finishing Performance and Carcass Characteristics in Lambs Fed All-Concentrate Diets

Abstract

Robles-Estrada, J.C, Barreras-Serrano, A., Contreras, G., Estrada-Angulo, A., Obregon, J.F., Plascencia, A. and Rios, F.G. 2009. Effect of two p-adrenergic agonists on finishing performance and carcass characteristics in lambs fed all-concentrate diets. J. Appl. Anim. Res., 36: 33–36. To assess the effect of feeding two (β-adernergic agonists [β-AA, type β1: 20 ppm ractopamine hydochloride (RAC), type β2: 6 ppm zilpaterol hydrochloride (ZIL)] on performance, 60 Pelibuey × Katahdin (34.4 ±2.94 kg) crossbred male lambs were used in a 32-d feeding trial. DM intake was not affected by treatments. Compared with controls, average daily gain and feed efficiency were improved with RAC supplementation, but final live weight, average daily gain and gain: feed were the best on ZIL supplemented group. No differences in carcass characteristics were detected among control group and RAC supplementation. It is concluded that β-AA supplementation increase growth performance in lambs as results of greater muscle accretion and for reduction of body fat. Use as feed additive, β2-AA compound has a greater response in feedlot lambs than β1-AA compound.