A comparison of two commercially available Escherichia coli J5 vaccines against E-coli intramammary challenge

The efficacy of two commercially available Escherichia coli J5 bacterins wa s investigated. Jersey cows were randomly assigned to one of three treatmen t groups: 1) unvaccinated controls, 2) vaccinated with J.VAC (Merial Limite d, Athens, GA), and 3) vaccinated with J5 bacterin. All cows were vaccinate d at drying off and at 2 wk before anticipated calving. Cows that were vacc inated with the J5 bacterin also received a third immunization at calving. One quarter of each cow was challenged with approximately 64 cfu off. coli at 14 to 30 d postcalving. Immunization by either vaccine did not influence the severity of coliform mastitis; however, the mean number of colony-form ing units off. coli recovered from challenged quarters was significantly lo wer for immunized cows than for control cows at 144 h postchallenge. Serum and mammary secretion immunoglobulin (Ig)G, IgG(1), and IgG(2) titers again st E. coli J5 whole-cell antigens were enhanced in vaccinated cows. Serum a nd mammary secretion IgM were not different among treatment groups. Somatic cell counts in milk from challenged quarters, rectal temperatures, and the clinical status of cows following intramammary challenge were not differen t among treatment groups.