Effect of zilpaterol hydrochloride on growth performance and carcass characteristics of wether goats

Abstract

Zilpaterol hydrochloride (ZH) supplementation was evaluated on performance of growing goats for the last 42 days before slaughter. Forty-eight Anglo-Nubian×Criollo animals (12 per treatment) were randomly assigned to one of four treatments (ZH at daily doses of 0.0, 0.1, 0.2 or 0.3mg/kg of BW in diet) in a complete block design. Basal diet contained 16.3% CP and 2.5 Mcal/kg ME. The ZH supplementation at doses of 0.1, 0.2 and 0.3mg/kg of BW increased ADG by 22.1, 54.0 and 56.6%, and gain/feed ratio by 20.0, 40.0 and 60.0%, respectively. The DMI (g/kg of BW0.75) increased quadratically (P=0.037). Carcass weight and dressing percentage (DP) augmented linearly (P≤0.031) as level of ZH increased in diet. The ZH supplementation increased (P≤0.023) longissimus muscle area (LM) and leg perimeter (LP) with a linear improvement (P<0.001) of LM area by 12.2% and 21.0% as ZH level increased in diet. The neck perimeter (NP) observed a quadratic trend (P<0.035) with greater values at 0.1 and 0.2mg/kg of ZH. For each increment of 0.1mg/kg in the ZH level, the percentage of fat in kidney, heart and pelvis tended to decrease by 4% (P=0.089). Other carcass characteristics were not significantly affected (P≥0.311) by ZH administration, but tended to reduce (P≤0.094) redness (a*) and chroma (C*) values in the longissimus muscle. It was observed a linear tendency to diminish pH (P=0.072). However, no differences (P>0.05) or trends (P>0.10) were detected on purge loss (PL) or cooking loss (CKL). Growth differences between wether goats fed ZH doses of 0.2 or 0.3mg/kg of BW were small, and therefore lower dose of 0.2mg/kg of BW seems enough to enhance growth. Moreover, the carcass characteristics showed minor differences between levels of ZH supplementation, and therefore could be considered that the lower dose of 0.1mg/kg of BW of ZH was sufficient to improve these traits. It is concluded that addition of ZH to diets of wether goats increased growth performance and carcass characteristics in a similar manner to that reported for cattle and sheep.