Influence of dietary zilpaterol hydrochloride on feedlot performance, carcass traits, chemical composition of longissimus muscle, and plasma metabolites of castrated male goats

To evaluate the influence of zilpaterol hydrochloride (ZH) supplementation on growth performance, carcass traits, chemical characteristics of the longissimus muscle (LM), and plasma metabolites, 16 Mahabadi castrated goats (29.93 +/- 1.84 kg) were individually fed a finishing diet without or with ZH supplementation dosed at 0.20 mg/kg BW daily. Zilpaterol was fed for 30 days with 3 days of withdrawal before harvest. Compared with the controls, ZH supplementation decreased dry matter intake and increased total weight gain, average daily gain, and gain for feed. Hot carcass weight, dressing percentage, and LM area were increased, but back fat thickness and kidney-pelvic fat were reduced in the group that received ZH. Supplemental ZH did not affect the full viscera mass or stomach complex, but it increased empty body weight (EBW) and reduced (as g/kg final EBW) the heart/lungs and kidney weights. Zilpaterol supplementation increased LM protein and moisture and decreased LM fat. The goats fed with ZH had lower serum concentrations of glucose, triglycerides, and cholesterol than the controls. It can be concluded that daily ZH supplementation at 0.20 mg/kg BW increases growth performance, feed efficiency, and dressing percentage in castrated goats as a result of greater muscle accretion and causes reduction of fat and visceral organ mass.