Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 1995
Publication Date: N/A
Technical Abstract: Outbreaks of E. coli O157:H7 have stimulated interest in reducing food-borne pathogens at all levels of production. Rumen fluid of well-fed animals has concentrations of volatile fatty acids (VFA) and pH which suppress enterobacteriaceae. However, if dietary stress is created by withholding food for 24-48 h, VFA and pH reach levels which allow significantly greater growth of enterobacteriaceae. Two groups of 4-month-old weaned calves (2 principals, 2 controls per group) were housed in containment barns. Food was withheld from the principals for 48 h prior to orally inoculating all calves with 10**7 CFU E. coli O157:H7 strain 3081. After inoculation, 3 of 4 controls shed the organism in feces for only 1-2 d at low levels, 1 calf shed 10**2 CFU/g and 2 calves less than 50 CFU/g. However, all principals shed the organism 10**4-10**6 CFU/g, and 3 were positive for the 15 d monitored. Repeated measures analysis showed that shedding by the groups was significantly different (P less than 0.0001). We conclude that fasted calves are more susceptible to infection by E. coli O157:H7 and that management practices which avoid dietary stress may reduce the spread of the organism among calves.