摘要
A feedlot experiment was conducted under commercial conditions in the Texas Panhandle using 3,757 feedlot steers (average of 94 steers/pen) to evaluate the effects of feeding zilpaterol hydrochloride with or without monensin and tylosin on feedlot performance and carcass characteristics. The experiment was conducted using a randomized complete block design. Treatments were arranged as a 2 (no zilpaterol vs. zilpaterol) × 2 (monensin and tylosin withdrawn vs. monensin and tylosin fed during the final 35 d on feed) factorial. Steers were fed for a total of 161 to 167 d, and treatments were administered during the final 35 d that cattle were on feed. When included in the diet, zilpaterol, monensin, and tylosin were supplemented at 8.3, 33.1, and 12.2 mg/kg (DM basis), respectively. Zilpaterol was included in the diet for 30 d at the end of the finishing period and withdrawn from the diet for the last 5 or 6 d cattle were on feed. Cattle were harvested and carcass data collected. There were no zilpaterol × monensin/tylosin interactions (P ≥ 0.12) for ADG or G:F. Feeding zilpaterol increased ADG (P < 0.001) by 0.20 kg and G:F (P < 0.001) by 0.029 kg/kg during the last 35 d on feed. Likewise, when feedlot variables were measured throughout the entire 161- to 167-d feeding trial, ADG (3.4%; P < 0.001) and G:F (3.9%; P < 0.001) were increased. Feeding zilpaterol increased (P < 0.001) dressing percent and HCW and decreased (P < 0.001) total liver abscess rate compared with controls. In addition, zilpaterol increased (P < 0.001) LM area by an average of 8.0 cm2. There was a zilpaterol × monensin/tylosin interaction (P = 0.03) for marbling score. Zilpaterol decreased (P < 0.001) marbling score regardless of monensin and tylosin treatment, although withdrawal of monensin and tylosin for 35 d decreased marbling to a greater extent (31 vs. 17 degrees). Zilpaterol decreased (i.e., improved; P < 0.001) calculated yield grade regardless of monensin and tylosin treatment, but feeding zilpaterol in combination with the withdrawal of monensin and tylosin for 35 d decreased calculated yield grade to a greater extent (0.49 vs. 0.29) compared with the zilpaterol, monensin, and tylosin combination treatment (zilpaterol × monensin/tylosin interaction, P = 0.03). Results suggest that monensin and tylosin can be withdrawn from the diet during the zilpaterol feeding period (final 35 d on feed) with minimal effect on animal performance, although feeding zilpaterol in combination with monensin and tylosin seemed to moderate effects on carcass quality.
摘要译文
在德克萨斯州狭长地带的商业条件下使用3,757个饲养场操舵（平均94个阉牛/笔）进行饲养场实验，以评估饲喂盐酸齐帕特罗与或不与莫能菌素和泰乐菌素对饲养场性能和胴体特性的影响。使用随机完全区组设计进行实验。处理安排为2（没有齐帕特罗与齐帕特罗）×2（莫能菌素和泰乐菌素相对于饲料中最终35天期间饲喂的莫能菌素和泰乐菌素）因子。饲喂阉鸡总共161至167天，并且在饲喂牛的最后35天期间进行处理。当包含在饮食中时，分别以8.3,33.1和12.2mg / kg（基于DM）补充齐帕特罗，莫能菌素和泰乐菌素。齐帕特罗在整理期结束时被包括在饮食中30天，并且在饲料中最后5或6天从饲料中退出。收获牛并收集胴体数据。对于ADG或G：F，没有齐帕特罗×莫能菌素/泰乐菌素相互作用（P≥0.12）。在饲料的最后35天，喂食齐帕特罗使ADG（P <0.001）增加0.20 kg，G：F（P <0.001）增加0.029 kg / kg。同样，当在整个161至167天的喂养试验中测量饲养场变量时，ADG（3.4％; P <0.001）和G：F（3.9％; P <0.001）增加。与对照组相比，喂食齐帕特罗增加（P <0.001）敷料百分比和HCW并降低（P <0.001）总肝脓肿率。此外，齐帕特罗增加（P <0.001）LM面积平均8.0 cm 2 。对于大理石花纹评分，存在齐帕特罗×莫能菌素/泰乐菌素相互作用（P = 0.03）。无论莫能菌素和泰乐菌素处理如何，齐帕特罗降低（P <0.001）大理石花纹评分，尽管莫能菌素和泰乐菌素35天的停药使大理石花纹减少程度更大（31对17度）。齐帕特罗减少（即改善;无论莫能菌素和泰乐菌素处理如何，P <0.001）计算产率等级，但与齐帕特罗，莫能菌素相比，喂食齐帕特罗与莫能菌素和泰乐菌素停用35天相比，计算产量等级更大（0.49对0.29），和泰乐菌素联合治疗（齐帕特罗×莫能菌素/泰乐菌素相互作用，P = 0.03）。结果表明，在齐帕特罗喂养期间（饲料最后35天），莫能菌素和泰乐菌素可以从饲料中提取，对动物性能影响最小，尽管给予齐帕特罗与莫能菌素和泰乐菌素相结合似乎对胴体品质有中等影响。
J. L. Montgomery;C. R. Krehbiel;J. J. Cranston;D. A. Yates;J. P. Hutcheson;W. T. Nichols;M. N. Streeter;R. S. Swingle;T. H. Montgomery. Effects of dietary zilpaterol hydrochloride on feedlot performance and carcass characteristics of beef steers fed with and without monensin and tylosin[J]. Journal of Animal Science, 2009,87(3): 1013-1023