EFFICACY OF DRY COW THERAPY AND A PROPIONIBACTERIUM-ACNES PRODUCT IN HERDS WITH LOW SOMATIC-CELL COUNT

Dry cow therapy and a Propionibacterium acnes product were evaluated i n four commercial herds with low SCC. Cows were randomly assigned with in herds to treatment groups of approximately 90 cows receiving dry co w therapy, P. acnes, dry cow therapy plus P. acnes, or no treatment in a factorial arrangement. Each lactating quarter of cows that received dry cow therapy was infused via the teat duct with 300 mg of cephapri n at drying off. Cows that received P. acnes were infused intravenousl y with .4 mg of killed P. acnes at drying off, 7 to 10 d prepartum, an d within 7 d after calving. A second prepartum injection of P. acnes i mmunostimulator was administered to cows that did not calve within 10 d after the first prepartum injection. Dry cow therapy enhanced bacter iological cures of IMI by Staphylococcus aureus and Corynebacterium bo vis at drying off. Dry cow therapy reduced incidence of new IMI by env ironmental streptococci and C. bovis that originated during the dry pe riod. Cows treated with P. acnes alone had a greater incidence of new IMI by Gram-negative bacilli originating during the dry period than di d cows in the other treatment groups. Incidence of clinical mastitis a t calving was greater for cows receiving no treatment than for cows re ceiving dry cow therapy, P. acnes, or dry cow therapy plus P. acnes.