Vaccination activity against avian influenza subtype H9 and Newcastle disease during immunization of egg-laying chickens

Relevance. The basis of protection against clinical expression of avian influenza subtype H9 (hereafter referred to as H9) is the level of immunity to this infection. The consequences of post-infection immunity do not exclude a decrease in production performance. It is therefore a priority to ensure post-vaccination immunity in birds. In the pathology of birds, the relationship between the epizootic situation of Newcastle disease (hereinafter — ND) and AI (H9) is important. Significant differences in the development of post-vaccination immunity against AI (H9) in replacement chickens may be due to the vaccines used in farms. The aim of the work is to compare the effectiveness of both monovaccines against HP (H9) and bivalent vaccines against this infection and NB, taking into account the differences in adjuvants in these drugs. Methods. Four experimental (20 heads each) and one control (10 heads each) group of chickens were formed for research. The experiment used birds that are not immune to HP (H9). In the experimental groups, chickens were vaccinated with inactivated vaccines at the age of 30 days. followed by their revaccination with a monthly interval. Blood serum sampling was performed every two weeks from the moment of initial immunization of chickens. The assessment of the level of immunity tension against GP (H9) and NB was carried out when RTGA was administered with specific antigens. Results. The dependence of the intensity and level of post-vaccination immunity on the difference in valence of the vaccines and adjuvants used was established. The use of monovaccines against AI (H9) did not provide a fundamental advantage over the use of bivalent vaccines against AI (H9) and ND, taking into account the adjuvants used.