Abstract
Salinas-Chavira, J., Domínguez-Muñoz, M., Díaz-Martínez, R., Cruz-Bautista, P., Montaño-Gómez, M.F. and Arzola-Alvarez, C. 2006. Effect of duration of zilpaterol hydrochloride treatment on carcass characteristics and weight gain in grazing Pelibuey lambs. J. Appl. Anim. Res., 29: 25–28.
The effect of zilpaterol hydrochloride (ZH) supplementation on carcass characteristics and weight gain were studied in grazing Pelibuey lambs. Thirty-six intact male Pelibuey sheep, (21.42±3.32 kg) were kept in three paddocks with Angleton grass (Dichantium aristatum) and were fed a supplement (sorghum, soybean meal, urea, molasses, tallow and minerals) containing 21.76% crude protein and 2.77 Meal I kg ME during 60 days feeding trial. Three paddocks formed the corresponding experimental groups: T1 (control), with no ZH in the supplement; T2 received 10 ppm ZH in supplement during the last 20 days of the trial and T3 received ZH during the last 30 days. The backfat was thinner (P<0.05) in both ZH groups than in the control group, measuring 0.28, 0.24 and 0.24 cm in T1, T2 and T3, respectively. The Longissimus dorsi measured 6.53, 6.24 and 5.84 cm2, respectively, and did not differ among dietary treatments. The average daily gain was also similar (P>0.05) among all experimental groups. It may be concluded that supplementation of zilpaterol hydrochloride during different intervals reduced the backfat cover in grazing Pelibuey sheep fed on supplemental concentrate.