Influence of beta-agonists (ractopamine HCl and zilpaterol HCl) on fecal shedding of Escherichia coli O157:H7 in feedlot cattle.

Abstract

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.

• Authors: Tom S Edrington, Russell L Farrow, Guy H Loneragan, Sam E Ives, Michael J Engler, John J Wagner, Marilyn J Corbin, William J Platter, David Yates, John P Hutcheson, Richard A Zinn, Todd R Callaway, Robin C Anderson, David J Nisbet
• Journal: Journal of food protection (J Food Prot) Vol. 72 Issue 12 Pg. 2587-91 (Dec 2009) ISSN: 0362-028X [Print] United States
• PMID: 20003743 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adrenergic beta-Agonists
• Phenethylamines
• Trimethylsilyl Compounds
• Zilpaterol
• ractopamine

Topics

• Adrenergic beta-Agonists (pharmacology)
• Animals
• Cattle
• Cattle Diseases (microbiology)
• Escherichia coli O157
• Feces (microbiology)
• Phenethylamines (pharmacology)
• Trimethylsilyl Compounds (pharmacology)