The acceptable age for brucellosis vaccination is 4 to 10 months. Only heifers should be vaccinated. The veterinarian is required to put a designated tattoo in the right ear and record the vaccination with the state veterinarian. Vaccinated dairy heifers are excused from testing until 20 months of age or until heavy with calf. It is spread from cow to cow only by a bull in natural service.
Infected cows fail to conceive or the embryo dies.
Heifers are more susceptible than cows. Vibriosis is difficult to diagnose. Recently developed methods of transporting and culturing the organisms have enhanced diagnostic capabilities. Vaccination for vibriosis is effective but immunity is short lived. Heifers should be vaccinated twice, once 60 to 90 days prior to breeding and again 30 days before breeding.