Aim: The purpose of this study was to prepare bivalent inactive Ornithobacterium rhinotracheale [O. rhinotarcheale) bacterin vaccines, to measure the levels of antibodies against antigens in blood sera and to determine the efficacies of different O. rhinotracheale vaccines in broilers.

Materials and Methods: The bivalent inactivated O. rhinotracheale bacterin vaccines were prepared from O. rhinotracheale serotype A and B strains using aluminium hydroxide (Al[OH]₃), mineral oil (MO), aluminium hydroxide + ginseng (Al[OH]₃ + G) and mineral oil + ginseng (MO + G). After the sterility and the safety tests, laboratory efficiencies of vaccines (challange/protection and serological potency) were controlled on the broilers (vaccinated at first day with a dose of 0.1 mL).

Results: According to the challenge results, all the vaccines were found to be effective as 100% for broilers. The vaccine containing mineral oil and ginseng (MO + G) as adjuvant induced significantly greater humoral immune response to the antigens than others.

Conclusion: The study showed that vaccination of broilers chicken at the first day age may effectively protect against O. rhinotracheale infections.