Influence of route of vaccine administration against experimental intramammary infection caused by Escherichia coli.

The route of immunization of a commercially available Escherichia coli J5 bacterin was investigated. Jersey cows were randomly assigned to one of three treatment groups: 1) unvaccinated (control), 2) vaccinated subcutaneously in the neck, and 3) vaccinated in the area of the supramammary lymph node. Cows were vaccinated at drying off and at 2 wk prior to anticipated calving. Two quarters of each cow were challenged with approximately 60 cfu of E. coli at 14 d postcalving. Route of immunization in the neck or the area of the supramammary lymph node did not influence severity of coliform mastitis. However, the mean number of colony-forming units of E. coli recovered from challenged quarters was significantly lower for vaccinated cows than for control cows at 24 h postchallenge. A quicker milk yield recovery following intramammary challenge was also observed for vaccinated cows. Serum immunoglobulin (Ig) G, IgG1, and IgG2 and whey IgG1 and IgG2 antibody titers against E. coli J5 whole-cell antigens were significantly enhanced in vaccinated cows. Somatic cell counts in milk from challenged quarters and rectal temperatures following intramammary challenge were not different for cows across treatment groups. Immunization did not prevent intramammary infection.