Efficacy of intramammary immunization with an Escherichia coli J5 bacterin

Intramammary immunization was investigated as a procedure to reduce the cli nical signs of coliform mastitis. Twenty-four cows were equally distributed to the following Escherichia coli 55 immunization schedules: 1) Subcutaneo us injection 14 d prior to the end of lactation, intramammary immunization 7 d after drying off, and subcutaneous injection 30 d into the dry period; 2) subcutaneous injections at drying off, at 30 d into the dry period, and within 12 h after calving; and 3) unimmunized controls. Intramammary immuni zations were the infusion of vaccine via the teat canal into each of the fo ur mammary glands. Cows were challenged by infusion of E. coli 727 into one uninfected mammary quarter at approximately 30 d after calving. Intramamma ry immunization enhanced antibody titers against E. coli 55 and E. coli 727 compared with subcutaneous immunization. Immunoglobulin G titers against E . coli 55 and E. coli 727 in whey were greater at the time of challenge and 7 d after challenge for cows that received the intramammary immunization t han for cows immunized by only subcutaneous injections. Serum IgG titers ag ainst E. coli 727 were enhanced at 7 d after challenge for cows receiving i ntramammary immunizations compared with conventionally immunized cows. Seru m IgM titers against E. coli 727 were higher at calving for cows receiving intramammary immunization compared with conventionally immunized cows. Immu nization schedule had minimal effect on systemic and local signs of clinica l mastitis following challenge.