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Influence of β-Agonists (Ractopamine HCl and Zilpaterol HCl) on Fecal Shedding of Escherichia coli O157:H7 in Feedlot Cattle

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Ractopamine HCl and zilpaterol HCl, β-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 β-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.
Edrington, Tom S. , Farrow, Russell L. , Loneragan, Guy H. , Ives, Sam E. , Engler, Michael J. , Wagner, John J. , Corbin, Marilyn J. , Platter, William J. , Yates, David , Hutcheson, John P. , Zinn, Richard A. , Callaway, Todd R. , Anderson, Robin C. , Nisbet, David J.
Includes references
Journal of food protection 2009 Dec., v. 72, no. 12
Journal Articles, USDA Authors, Peer-Reviewed
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