Effectiveness of vaccination of broiler chicken parent flock against infectious bronchitis of chickens

The infectious bronchitis virus (IBV) in chickens is one of the causes of economic losses in the poultry industry worldwide. The economic consequences include mortality, slower growth and high percentage of poultry culling, reduced egg production, poorer egg quality and reduced egg hatching. Live and inactivated vaccines are used to prevent the disease. The high variability of the virus and the appearance of new serotypes justify the need for constant serological monitoring of the intensity of specific immunity in different groups of birds and periodic changes in vaccination programs. The research goal was to evaluate the effectiveness of the vaccination program of the parent flock of broiler chickens against the IBV against the background of using a live vaccine based on the Massachusetts H-120 serotype strain. The vaccination program included the immunization of poultry by the spray method on the first days of life, by the drinking method on the 12th day, and by the ocular method on the 63rd, 109th, 128th, and 158th days. The control of immunity stress was carried out by determining the titer of specific antibodies by enzyme immunoassay. High values of average antibody titers (16951) and a low coefficient of variation (18.7%) were found which indicated a high level of active immunity and reliable protection of broiler chicken parent flock against the IVB field strains. The use of this scheme will ensure the protection of young broiler chickens by transmitting maternal antibodies on the first days of life, thereby reducing possible economic losses caused by the virus and ensuring the epizootic well-being of the poultry industry.