Infection and serological responses in cattle given 45/20 vaccine and later challenged with Brucella abortus.

One of 2 groups of 15 non-pregnant cows was vaccinated twice 6 weeks apart by the subcutaneous route with a killed adjuvant 45/20 vaccine. At the time of the first vaccination a bull was introduced for a period of 14 weeks. All animals were challenged with 1.