Zilpaterol hydrochloride improves growth performance and carcass traits without affecting wholesale cut yields of hair sheep finished in feedlot

Rolando Rojo-Rubio,Leonel Avendaño-Reyes,Benito Albarrán,José F Vázquez,Sergio A Soto-Navarro,Juan E Guerra,Ulises Macías-Cruz

doi:10.1080/09712119.2017.1307756

Abstract

ABSTRACTFourteen Dorper × Pelibuey ram lambs (initial body weight [BW] = 37.4 ± 1.0 kg and age = 4.5 mo) were housed in individual pens during a 30-d feeding period, and then slaughtered to determine the effects of zilpaterol hydrochloride (ZH) supplementation on productive performance, carcass characteristics and wholesale cut yields. Lambs were assigned under a randomized complete block design (initial BW as blocking factor) to one of two dietary treatments: basal diet without (control) or with 10 mg daily of ZH/lamb. Lambs fed ZH had greater (P ≤ .04) final BW, average daily gain and dry matter intake, but similar (P = .24) feed efficiency compared with control lambs. Hot and cold carcass weight, dressing percentage, longissimus muscle area and leg perimeter were greater (P ≤ .05) for ZH-fed lambs than for control lambs. With exception of blood percentage which decreased (P < .01) with ZH, wholesale cut yields and non-carcass components were unaffected (P ≥ .12) by ZH supplementation. In conclusion, ZH can be used to improve growth rate and dressing percentage, but not to increase wholesale cut yields in feedlot finishing ram lambs.

Highlights

Growth of the sheep meat industry throughout the world has been slow compared with meat industries of other domestic animals
Studies done with ram lambs from hair genotypes have reported up to 43 and 35% more daily weight gain and feed efficiency, respectively, when zilpaterol hydrochloride (ZH) is supplemented (Ríos-Rincón et al 2010; LopezCarlos et al 2011)
Capsules were administered for 28 d followed by a 2-d withdrawal period. bConformation was evaluated using a numerical scale from 1 = bad to 10 = excellent (Smith et al, 2001). cLM = Longissimus muscle

Summary

Introduction

Growth of the sheep meat industry throughout the world has been slow compared with meat industries of other domestic animals. The use of β2adrenergic agonists (β2-AA) as growth promoters has demonstrated to increase sheep meat production by improving protein deposition in muscle (Domínguez-Vara et al 2013). The use of such technology in the lamb fattening systems could be a nutritional strategy to improve their competitiveness. Studies done with ram lambs from hair genotypes have reported up to 43 and 35% more daily weight gain and feed efficiency, respectively, when ZH is supplemented (Ríos-Rincón et al 2010; LopezCarlos et al 2011). The level of response expected by ZH supplementation in lambs has not been consistent among studies related to growth, feed efficiency, dressing percentage and internal fat deposition

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Conclusion