Vaccination of cows with an Escherichia coli bacterin for the prevention of naturally occurring diarrheal disease in their calves.

A formalin-killed Escherichia coli bacterin composed of 6 enterotoxigenic strains of the organism prepared from calves with diarrheal disease with field tested for efficacy against naturally occurring diarrheal disease in young calves. The bacterin was tested in 23 privately owned beef herds in Montana involving 3,508 cows and their calves. About half the cows in each herd were given 2 subcutaneous vaccinations before calving and the other half (controls) were injected twice with a placebo. Almost all of the participating herds had a record of acute diarrheal disease. The number of calves from vaccinated dams that died of diarrheal disease was significantly less (P = 0.004) than the number of calves from control dams that died of diarrheal disease (60 vs 99 calves). There was no significant difference in the number of calves in the groups that developed mild diarrhea. There was marked interherd variation in vaccinal efficacy, possibly due in part to differences in the cause of diarrheal disease between herds. Colostral agglutinating antibody titers against formolized cells of each of the 6 vaccinal strains of E coli were markedly higher in vaccinated dams than in control dams. The agglutinating antibody titers were highest against enterotoxigenic E. coli strains 4 and 5 and lowest against strains 2 and 6. Presumably, colostral antibody passively transferred to the calf at the time of nursing was responsible for the protection observed.