Influence of body condition and forage type on prevalence of Escherichia coli O157:H7 and Salmonella in grazing beef cows.

ABSTRACT

AIM: To determine the influence of body condition (BC) and forage type on the prevalence of faecal shedding of Escherichia coli O157H7 and Salmonella from beef cows. METHODS AND RESULTS: Thin or moderately conditioned cows (n = 115) were randomly assigned to graze either common bermudagrass (n = 3 pastures) or toxic endophyte-infected tall fescue (n = 3 pastures) for 62 days. Faecal samples were collected on day 0, 30 and 62. Overall percentage of faecal samples positive for E. coli O157H7 was 2.6% and 2.0% for Salmonella. Percentage of cows positive for both E. coli O157H7 and Salmonella on at least one occasion was 6.1%. BC, forage type or the interaction did not influence the prevalence of E. coli O157H7 or Salmonella in the faeces of cows. CONCLUSIONS: BC at initiation of the grazing period or loss of BC in moderate conditioned cows during the grazing period did not influence faecal shedding of E. coli O157H7 or Salmonella. Consumption of either forage type did not influence faecal shedding of either E. coli O157H7 or Salmonella in beef cows of thin or moderate BC. SIGNIFICANCE AND IMPACT OF THE STUDY Change in BC that typically occurs during the normal production cycle in grazing cows did not influence faecal shedding of pathogenic bacteria regardless of forage type.