The prevalence of verotoxins, Escherichia coli 0157 : H7, and Salmonella in the feces and rumen of cattle at processing

Fecal samples collected from cattle at processing during a 1-year period we re tested. for verotoxins (VT1, VT2), Escherichia coli 0157:H7, and Salmone lla. Verotoxins were detected in 42.6% (95% CI, 39.8% to 45.4%), E. coli 01 57:H7 in 7.5% (95% CI, 6.1% to 9.1%), and Salmonella in 0.08% (95% CI, 0.00 4% to 0.5%) of the fecal samples. In yearling cattle, the median within-lot prevalence (percentage of positive samples within a lot) was 40% (range, 0 % to 100%) for verotoxins and 0% for E. coli 0157:H7 (range, 0% to 100%) an d Salmonella (range, 0% to 17%). One or more fecal samples were positive fo r verotoxins in 80.4% (95% CI, 72.8% to 86.4%) of the lots of yearling catt le, whereas E. coli 0157:H7 were detected in 33.6% (95% CI, 26.0% to 42.0%) of the lots. In cull cows, the median within-lot prevalence was 50% (range , 0% to 100%) for verotoxins and 0% (range, 0% to 100%) for E. coli 0157:H7 and Salmonella (range, 0% to 0%). Verotoxins were detected in one or more fecal samples from 78.0% (95% CI, 70.4% to 84.2%) of the lots of cull cows, whereas E. coli 0157:H7 were detected in only 6.0% (95% CI, 3.0% to 11.4%) of the lots of cull cows. The prevalence of verotoxins in fecal samples wa s lower in yearling cattle than in cull cows, whereas the prevalence of E. coli 0157:H7 in fecal samples was higher in yearling cattle lan in cull cow s. The prevalence of E. coli 0157:H7 in fecal samples was highest in the su mmer months. Rumen fill, body condition score, sex, type of cattle (dairy, beef), and distance travelled to the plant were not associated with the fec al prevalence of verotoxins or E. coli 0157:H7. The prevalence of verotoxin s in fecal samples of cull cows was associated with the source of the cattl e. It was highest in cows from the auction market (52%) and farm/ranch (47% ) and lowest in cows from the feedlot (31%). In rumen samples, the prevalen ce of verotoxins was 6.4% (95% CII 4.2% to 9.4%), and it was 0.8% (95% CI, 0.2% to 2.3%) for E. coli 0157:H7, and 0.3% (95% CI, 0.007% to 1.5%) for Sa lmonella.