Influence of zilpaterol hydrochloride on growth and carcass characteristics of Pelibuey lambs

Abstract

To evaluate the effect of different doses of the feed additive beta-agonist, zilpaterol hydrochloride (ZH) on performance and carcass characteristics of lambs, twelve intact male Pelibuey lambs (28.7+/-2.7 kg) were kept in individual pens and randomly assigned to three treatment (T) diets (four lambs per diet); lambs on T1 were fed the diet without additive, on T2 and T3 were fed the same diet and 4.35 and 6.0 mug ZH/g DM, respectively, for a second feeding trial. Lambs on T2 and T3 had the same (P<0.05) daily dry matter intake (1460.0 and 1375.0 g, respectively), average daily gain (365.0 and 347.0 g) and feed efficiency (4.0 and 4.0, respectively); however, both were significantly higher than those lambs on T1 (1175.0 g, 140.0 g and 9.0, respectively). All lambs deposited the same (>0.05) subcutaneous fat. Lambs on T1 and T2 had similar (P>0.05) Longissimus dorsi area (9.8 and 11.2 cm(2) respectively), but both were lower (P<0.05) than lambs on T3 (14.2 cm(2)). It is concluded that addition of ZH to a,high concentrate diet fed to Pelibuey lambs showed improved performance.