The effects of zilpaterol hydrochloride supplementation on market dairy cow performance, carcass characteristics, and cutability

Market dairy cows (n = 34) were used to determine the effects of zilpaterol hydrochloride (ZH) supplementation, in addition to concentrate feeding, on growth performance, carcass characteristics, and carcass yields. Cows were stratified by BW and randomly assigned to 1 of 2 treatments: 1) concentrate fed for 42 d (control) or 2) concentrate fed for 42 d with ZH (8.33 mg/kg) from d 19 to 39. Dietary supplementation of ZH had no effect (P > 0.05) on locomotion score, BCS, BW, ADG, G:F, or DMI over the course of the feeding period. Supplementation with ZH increased (P < 0.01) ultrasound LM area and decreased (P = 0.03) i.m. fat percentage but had no effect on 12th-rib backfat. Carcasses from zilpaterol-fed cows had greater (P = 0.02) dressing yields, larger (P < 0.01) LM areas, and improved (P = 0.02) USDA YG. Carcasses from zilpaterol-fed cows also had increased (P < 0.05) primal, subprimal, and selected added-value cut yields on a weight basis as well as on a percent of chilled side weight basis. According to the results in this study, supplementing market dairy cows with zilpaterol improved carcass composition and yields without having adverse effects on overall carcass quality.