PRELIMINARY-RESULTS FOR THE VACCINATION OF PREGNANT CATTLE WITH BRUCELLA-ABORTUS STRAIN-19 OR BRUCELLA-ABORTUS RB51

As cattle are the most susceptible to Brucella abortus infections when these animals are pregnant, a study was done to compare the effects o f vaccine strains 19 and RB51. Three cows served as controls, six rece ived 4x10(7) strain 19 subcutaneously into the neck and six received 5 x10(7) strain RB51 by the same route. Although one of the controls abo rted, this was subsequently found to be due to a Staphylococcus aureus infection. The pregnant cattle, that were vaccinated with strain 19, showed sero-conversion and one cow aborted with B. abortus S19 isolate d from the fetus. Pregnant cattle that received B. abortus RB51 neithe r showed any sere-conversion nor any abortions.