Department of Animal Science, Oklahoma State University, Stillwater 74078, USA.
J Anim Sci. 2009 Nov;87(11):3677-85. doi: 10.2527/jas.2009-1816. Epub 2009 Aug 14.
The impact of zilpaterol hydrochloride (ZH) on carcass yield, composition, and tenderness was evaluated using 384 beef steers in a randomized complete block design. Main effects were the addition of 0 or 8.3 mg/kg of ZH for the final 20 d of feeding and each inclusion level was paired with withdrawal periods of 3, 10, 17, or 24 d. The 2 animals with BW closest to the pen average were selected for carcass fabrication to determine carcass yield, composition, and tenderness. The carcasses from animals fed ZH had greater (P = 0.008) individual side weights. Carcass fat determinations were unchanged (P = 0.70) by ZH. Weights of the strip loin (P = 0.01), peeled tenderloin (P = 0.02), and top sirloin butt (P < 0.001) were all improved with ZH. When expressed as a proportion of carcass weight, ZH increased percentage of carcass in the top sirloin butt (P = 0.006), bottom sirloin tri-tip (P = 0.02), top inside round (P = 0.002), bottom round flat (P = 0.001), and flank steak (P = 0.02). A longer withdrawal time (WT) increased (P < 0.001) carcass weights. Shoulder clod weights were greatest (P < 0.001) with 17-d WT from ZH, whereas chuck roll weights were greatest (P = 0.02) at 17 and 24 d of WT. Peeled tenderloins, top sirloin butts, and eye of rounds responded to WT, with increased (P < 0.001) weights seen at 10 d of WT as compared with all other WT. Shear force values were greater at each of the 3 aging times, 7 d (P < 0.001), 14 d (P < 0.001), and 21 d (P = 0.003), in steaks from ZH-fed steers compared with control steers. Protein percentages were greater in ZH steaks (P = 0.03) and ZH ground beef trim (P < 0.001). Percent moisture was increased (P < 0.001) in strip loin steaks at 3 and 10 d WT. Ground beef trim had an increase (P = 0.04) in percent moisture and a decrease (P = 0.01) in percent fat at 10 d WT. Carcass weights and yields were improved with ZH feeding and may continue to improve even up to 10 d after withdrawal of the supplement. Tenderness was slightly reduced with ZH supplementation but was unaffected by WT. Zilpaterol hydrochloride can be a valuable supplement to finishing beef steers to improve carcass lean yields and composition.
盐酸齐帕特罗（ZH）对 384 头肉牛的胴体产率、组成和嫩度的影响采用随机完全分组设计进行评估。主要效应是在最后 20 天的饲养中添加 0 或 8.3mg/kg 的 ZH，每个添加水平都与 3、10、17 或 24 天的撤出期配对。选择与畜群平均体重最接近的 2 头动物进行胴体加工，以确定胴体产率、组成和嫩度。饲喂 ZH 的动物的胴体侧重较大（P=0.008）。胴体脂肪测定不受 ZH 影响（P=0.70）。带骨里脊（P=0.01）、去皮里脊（P=0.02）和上臀肉（P<0.001）的重量均因 ZH 而提高。当表示为胴体重量的比例时，ZH 增加了上臀肉（P=0.006）、下臀肉三角肉（P=0.02）、上内圆肉（P=0.002）、下臀肉（P=0.001）和腹肉（P=0.02）的胴体比例。较长的撤出时间（WT）增加了（P<0.001）胴体重量。肩部肉块重量最大（P<0.001），WT 为 17 天，而肩卷重量最大（P=0.02），WT 为 17 和 24 天。去皮里脊、上臀肉和牛眼肉对 WT 有反应，与所有其他 WT 相比，WT 为 10 天时的重量增加（P<0.001）。与对照牛相比，ZH 饲养的牛的牛排在 3 个老化时间（7d、P<0.001；14d、P<0.001；21d、P=0.003）时的剪切力值均较高。ZH 牛排（P=0.03）和 ZH 绞碎牛肉修剪（P<0.001）中的蛋白质百分比较高。在 3 和 10d WT 的里脊牛排中，水分百分比增加（P<0.001）。在 10d WT 时，绞碎牛肉修剪的水分百分比增加（P=0.04），脂肪百分比降低（P=0.01）。ZH 饲养可提高胴体瘦肉产率和组成，提高胴体重量和产率，甚至在撤出补充剂后 10 天仍可能继续提高。ZH 补充剂使嫩度略有降低，但不受 WT 影响。盐酸齐帕特罗可以作为一种有价值的肉牛育肥补充剂，提高胴体瘦肉产量和组成。
