The Relationship of the Characteristics of Feedlot Pens to the Percentage of Cattle Shedding \u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 Within the Pen

This study was designed to discover relationships between characteristics of feedlot pens and the percentage of cattle shedding Escherichia coli O157:H7. Twenty-nine pens from five Midwestern feedlots were each sampled once between June and September, 1999. Feces were collected from all cattle in each pen. E. coli O157:H7 was isolated from the feces of 714 of 3162 cattle tested (23%), including at least one animal from each of the 29 pens. Pen prevalence did not differ between feedyards, but did vary widely within feedyards. Muddy pens were more likely to have a higher pen prevalence than normal pens

Influence of Restricted Intake and Reduced Dietary Starch on Colonic pH and \u3ci\u3eE. coli \u3c/i\u3ePrevalence

Ninety feedlot steers were used to test the effects of reducing dietary starch and intake on colonic pH, VFA, total and acid-resistant coliform and E. coli populations, and E. coli O157:H7 shedding. When corn bran and wet corn gluten feed (WCGF), or high moisture corn and WCGF were substituted for dry rolled corn, colonic pH increased while VFA concentration decreased. The corn bran and WCGF diet reduced acid-resistant E. coli shedding. Restricting intake increased colonic pH and decreased VFA concentration, but did not affect acid-resistant E. colishedding. Prevalence of E. coliO157:H7 was not affected by diet or intake

A Diagnostic Strategy to Classify Pens of Feedlot Cattle by the Prevalence of \u3ci\u3eEscherichia coli \u3c/i\u3eO157:H7 Fecal Shedding

This study evaluated two pen testing strategies to predict the percentage of cattle in a pen shedding detectable E. coli O157:H7. Culture of a composite fecal sample most accurately detected pens with 37% or more cattle shedding E. coli O157:H7 in feces. A new pen test device most accurately detected pens with 16% or more individuals shedding. The likelihood of detecting E. coli O157:H7 with either method increased as pen prevalence increased. If both pen-level test methods were used together, pens could be classified as high, medium or low prevalence with less labor and expense than testing individual cattle

Longitudinal Patterns of Fecal Shedding of \u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 by Feedlot Cattle

To describe the prevalence, incidence, and duration of fecal shedding of E. coli O157:H7, 99 feedlot steers were individually tested each week of the feeding period for presence of E. coli O157:H7 in rectal feces. E. coli O157:H7 was recovered from each animal at least once during the study. Both the incidence and mean duration of shedding peaked during the middle of the feeding period. The percentage of cattle shedding E. coli O157:H7 ranged from 1% to 80% over the course of the feeding period and was affected by both the incidence and the duration of shedding