A randomized controlled trial to assess the impact of dietary energy sources, feed supplements, and the presence of super-shedders on the detection of escherichia coli O157:H7 in feedlot cattle using different diagnostic procedures

Natalia Cernicchiaro, David L. Pearl, Scott A. McEwen, Henry N. Zerby, Francis L. Fluharty, Steven Christopher Loerch, Michael D. Kauffman, Jaime L. Bard, Jeffrey T. Lejeune

Research output: Contribution to journalArticle

Abstract

Alteration of the gastro-intestinal tract through manipulation of cattle diets has been proposed as a preharvest control measure to reduce fecal shedding of Escherichia coli O157:H7. The objective of this study was to examine the effects of the energy source's moisture content (high moisture corn and dry whole-shelled corn), two natural feed supplements (Saccaromyces cerevisiae boulardii CNCM 1079-Levucell and Aspergillus oryzae-Amaferm®), and two levels of vitamin A (2200 IU/kg and no supplementation) on the fecal excretion of E. coli O157:H7 in naturally infected cattle. One hundred sixty-eight Angus-cross beef steers were randomly allocated to 24 pens, and each pen was assigned 1 of 12 dietary treatments in a randomized complete block design. E. coli O157:H7 was detected by rectoanal mucosal swab (RAMS) and fecal grab samples using immunomagnetic separation (IMS) and standard microbiological techniques. On the basis of multivariable multilevel logistic regression models, we found a statistically significant (p < 0.05) increase in the prevalence of E. coli O157:H7 in animals fed dry whole-shelled corn in models based on fecal-IMS, and this effect was increased if a super-shedding animal (shedding > 104 colony forming units of E. coli O157:H7 per gram of feces) was present in the pen at the time of testing relative to animals fed high moisture corn and nonexposed to super-shedders. However, in similar models based on RAMS-IMS testing, the effect of corn type on the prevalence of E. coli O157:H7 varied with the type of feed additive used. Being exposed to a super-shedding pen-mate also increased the odds of being positive to E. coli O157:H7 in the RAMS-IMS models. These models demonstrate that the impact of different supplements may vary with the diagnostic test used, and that further research into the biological significance of differences between RAMS- and fecal-IMS test results is warranted.

Original languageEnglish (US)
Pages (from-to)1071-1081
Number of pages11
JournalFoodborne Pathogens and Disease
Volume7
Issue number9
DOIs
StatePublished - Sep 1 2010

ASJC Scopus subject areas

  • Microbiology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Animal Science and Zoology

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