EN
Haemophilus somnus was considered to be the main cause of the respiratory and reproductive disorders of bulls from the Bulls’ Rearing Station P. The animals were vaccinated by means of Somnuvac® vaccine. The immunization programme were verified by serological tests (bacterial agglutination, ELISA, immunoblotting), and by parameters of performance (percent of morbidity, costs of treatment, body weight in 400 days after birth, culling rates of bulls with reproductive and other disorders). Productivity results were compared with the results from the year before the immunization programme was introduced. The incidence of respiratory disorders was decreased from 23.4% (one year before vaccination) to 9% (in the year of vaccination); the costs of treatment decreased 2.5 fold, and the culling rate of bulls with reproductive disorders decreased 3 fold. Intensive humoral response against H. somnus in immunized animals was confirmed in all serological tests.