Effects of dietary zilpaterol hydrochloride on growth performance, carcass characteristics, and serum compositions of Hanwoo bulls

This study was conducted to determine the effects of zilpaterol hydrochloride (ZH) on the grovrth performance and carcass characteristics of Hanwoo bulls. Twenty Hanwoo bulls (653 ± 22.1) were randomly assigned by body weight (BW) to determine the effects of feeding zilpaterol hydrochloride (Ten bulls with 8.3 mg/kg ZH and ten bulls without ZH) on the ultrasound measurement, carcass traits, and serum compositions. Treatments comprised diets with and without ZH supplemented for 20 days prior to harvest with three days withdrawal period. Treatment of ZH led to an increase either in the final BW or average daily gain (ADG) in Hanwoo bulls (P<0.05). There was no treatment effect on the back fat thickness, ribeye area, and marbling score (P>0.05). ZH treatment tended to increase at dressing percentage (P=0.068). There was a high positive correlation (R²=0.9226) at treatment but relatively low positive correlation (R²=0.7156) at control between ultrasound longissimus muscle area and ribeye area. The treatment of ZH affects the serum triglyceride and non-esterified fatty acid (P<0.05). Moreover, we demonstrated that the treatment of ZH did not have a negative effect on the serum level of GOT or GPT of Hanwoo bulls. We concluded that the treatment of ZH has little impact on the carcass trait of Hanwoo bulls regardless of the positive effect on BW and ADG. However, dietary ZH increased lipid related serum metabolites of Hanwoo bulls at 14^th day.