SUMMARY Enteric colibacillosis was produced in all of 13 colostrum-fed calves obtained from nonvaccinated dams after calves were given oral challenge inoculation with Escherichia coli strain B44. Of 9, 6, and 7 calves obtained from dams given homologous vaccination with viable cells, formalin-killed cells, and concentrated crude toxin preparation, respectively, 7, 6, and 4 calves were protected after they were given oral challenge inoculation. The efficacies of the 3 vaccines to protect calves were similar for the first 30 days after the cows were vaccinated. The efficacy of the toxin preparation decreased with time after the cows were vaccinated, as evidenced by diarrhea of 4+ intensity in 3 of 4 calves born more than 30 days after the 2nd vaccination of the dam. The disease syndrome included profuse watery diarrhea, severe dehydration, apathy, decrease in body temperature, and prostration. The affected calf often died if not treated or if treated too late. The onset of signs in calves from nonvaccinated dams occurred an average of 6.5 hours after the calf was given the challenge inoculation. The average time from challenge inoculation to the calf becoming moribund was 35 hour S. Escherichia coli with colony type identical to strain B44 was detected in the feces of calves from vaccinated and nonvaccinated dams during the 4 days after challenge inoculation was given. Bacteremia did not occur until the calves were moribund. Gross pathologic changes were not evident at necropsy.
No takes yet. Share an insight, caveat, or question.
Myers et al. (1973) studied this question.