Bulletin

An injectable vaccine have become popular as a preventive measure against bovine mastitis. This vaccine is designed to be administered three times to healthy pregnant cows: 45 days before, 10 days before, and 52 days after the expected calving date. This protocol requires different vaccination dates for each individual cow, which can be time-consuming on farms with many cows. To test the utility of herd-based vaccination as an alternative, we simultaneously administered the mastitis vaccine to all of the cows in a milking herd. The commercial vaccine was administered on the same days to 20 Holstein cows. Three doses were administered at 5-week intervals. Milk samples from five of the cows were collected every week for the measurement of the somatic cell count (SCC) and viable bacterial count (VBC), and the species identification was performed according to conventional methods. The incidence of mastitis was compared with that of 14 non-vaccinated cows kept in the same barn during the previous year. The SCCs and VBCs of the five vaccinated cows were all in the normal range during the study period, although a transient increase in both variables was observed. The number of cows treated for mastitis, the number of cases of mastitis and the duration of mastitis treatment in the non-treated group were three of 14 cows (21.4%), 21 cases, and 3.6±3.1 days; the corresponding values in the simultaneously treated group were one of 20 cows (0.5%), one case, and 3.6±1.6 days. These results indicate that the simultaneous administration of the vaccine to a milking herd was as effective as the designed administration protocol for preventing mastitis, and the simultaneous administration can be expected to reduce the time and effort required for herd management.