Effects of Zilpaterol Hydrochloride with a Combination of Vitamin D3 on Feedlot Lambs: Growth Performance, Dietary Energetics, Carcass Traits, and Meat Quality.

The study evaluated the impact of supplementing ZH in combination with D3 on growth performance, energy efficiency, carcass traits, and meat quality of feedlot lambs. Thirty-two Dorper x Katahdin cross lambs (37.3±5.72 kg) were utilized in a 29 d experiment in a complete randomized block design with a 2x2 factorial structure consisting of two levels of ZH for 26 d (0 and 0.20 mg /kg PV-1) and two levels of D3 for 7 d (0 and 1.5x106 IU/d-1). ZH improved (P≤0.05) average daily gain (ADG) and feed efficiency by 9.9% and 17.8%, respectively, as well as hot carcass weight (HCW) and dressing carcass by 4.3% and 2.6%, respectively. (p≤0.03). However, ZH increased (p<0.01) muscle pH and Warner-Bratzler shear force (WBSF) (2.5 and 23.0%, respectively). D3 supplementation negatively affected (P≤0.02) dry matter intake (DMI) (last 7 d) and ADG by 15.7% and 18.1%. On the other hand, D3 improved the pH of the longissimus muscle (LM) by 1.7% (p=0.03) without affecting WBSF. When D3 was supplemented in combination with ZH, it was observed that meat quality was improved by reducing muscle pH compared to lambs treated only with ZH. However, D3 did not improve meat tenderness produced by ZH supplementation.