Evaluation of a direct-fed microbial product effect on the prevalence and load of escherichia coli 0157.-H7 in feedlot cattle

Abstract

Direct-fed microbials (DFM) have been identified as potential preharvest interventions for the reduction of foodborne bacterial pathogens such as Escherichia coli 0157:H7. This study evaluated the efficacy of a DFM consisting of Bacillus subtilis strain 166 as an antimicrobial intervention strategy for the reduction of prevalence and load of E. coli 0157:H7 in feces and on hides of feedlot cattle. Cattle (n = 526) were divided among 16 feedlot pens. Half of the pens received the DFM. and the other half did not. Hide and fecal samples were collected from each animal on days 28, 63, and 84 of the feeding trial. Over the course of the 84-day feeding period, there were no significant differences observed between treatments for either hide or fecal prevalence of E. coli 0157:H7, or for the percentage of animals that were shedding E. coli 0157:H7 at high levels (&200 CFU/g) in their feces or harboring E. coli 0157:H7 at high levels (s40 CFU/cm2) on their hides, In addition, there was no significant difference between the average daily gains for the treated and control groups, with both groups averaging 1,3 kg/day. We concluded that the DFM tested would not be an effective preharvest intervention against E. coli 0157:H7.