Vaccination of chickens against Ornithobacterium rhinotracheale infection.

Vaccination of young broilers with inactivated vaccines against experimental Ornithobacterium rhinotracheale challenge was found to be effective, but the results of vaccination were influenced, in a negative way, by the presence of maternal antibodies. The use of a strong adjuvant, such as mineral oil, in a bacterin was necessary to obtain good protection when maternal antibodies were present. Vaccination of broiler breeders resulted in high serologic responses and protection of their progeny against experimental O. rhinotracheale challenge up to an age of 4 wk. Vaccination of broilers with a live vaccine was found to be effective when the maternal antibody levels were low. A combination of vaccinating the breeders with a bacterin and their progeny with a live vaccine at approximately 3 wk of age seems to be the best way to protect broilers against O. rhinotracheale infection.