Food and Feed Safety Research Unit, Agricultural Research Service, U.S. Department of Agriculture, College Station, Texas 77845, USA.
J Food Prot. 2009 Dec;72(12):2587-91. doi: 10.4315/0362-028x-72.12.2587.
Ractopamine HCl and zilpaterol HCl, beta-agonists recently approved for use in feedlot cattle to improve performance traits and carcass leanness, were examined for their effects on fecal shedding of Escherichia coli O157:H7 in feedlot cattle. Fecal samples (n = 2,454) were obtained from four experiments (one ractopamine HCl, three zilpaterol HCl) over the course of a 3-year period, either by rectal palpation (ractopamine HCl experiment) or from pen-floor fecal pats. Samples were cultured quantitatively and qualitatively for E. coli O157:H7. No significant treatment differences were detected for fecal prevalence of E. coli O157:H7 in the ractopamine HCl experiment. Zilpaterol HCl feeding had no effect (P > 0.20) on fecal shedding in the first or second experiments, with overall E. coli O157:H7 prevalence relatively low (<7%). In the third zilpaterol HCl experiment, the percentage of fecal samples that were E. coli O157:H7 positive following qualitative culture was higher (P < 0.05) in the zilpaterol HCl treatment (10.3%) than for the control (6.1%). The current research showed minimal effects of beta-agonists on fecal shedding of E. coli O157:H7 and indicated that these compounds (fed immediately prior to slaughter) are not a cause for concern from a food safety standpoint.
盐酸莱克多巴胺和盐酸齐帕特罗，β-激动剂最近被批准用于牛饲料中以改善生产性能和胴体瘦肉率，研究了它们对牛粪便中大肠杆菌 O157:H7 排泄的影响。在 3 年的时间里，通过直肠触诊（盐酸莱克多巴胺实验）或从栏位地板粪便垫中获得了来自四个实验（一个盐酸莱克多巴胺，三个盐酸齐帕特罗）的 2454 份粪便样本，对其进行定量和定性培养以检测大肠杆菌 O157:H7。在盐酸莱克多巴胺实验中，粪便中大肠杆菌 O157:H7 的流行率没有显著的处理差异。在第一或第二个实验中，盐酸齐帕特罗的喂养对粪便排泄没有影响（P > 0.20），大肠杆菌 O157:H7 的总体流行率相对较低（<7%）。在第三个盐酸齐帕特罗实验中，在定性培养后，粪便中大肠杆菌 O157:H7 阳性的样本比例在盐酸齐帕特罗处理组（10.3%）中高于对照组（6.1%）（P < 0.05）。目前的研究表明，β-激动剂对大肠杆菌 O157:H7 的粪便排泄影响很小，并表明这些化合物（在屠宰前立即喂养）从食品安全的角度来看不是一个值得关注的原因。
