EN
The observations were done on three groups of sheep: immunized before mating, immunized before mating and experimentally infected in the 2nd half of pregnancy, unimmunized and uninfected controls. The progeny of sheep was experimentally infected by pathogenic strains of Listeria at the age about 8 weeks to examine the level of maternal immunity. Adults were vaccinated with an own live avirulent vaccine against listeriosis. The animals were examined clinically, microbiologically, serologically and anatomopathologically. The vaccine used before mating protected pregnant ewes and their progeny. Vaccination before mating also increased the concentration and prolonged persistence of agglutinins in colostrum and milk.