[Vaccination schemes against Newcastle disease in poultry]

Two schemes of vaccination against pseudo-pest (A and B) were tested on broiler-chickens and two schemes (C and D)--on parent form birds. Vaccine of the La Sota strain was used for the broilers and was administered twice at differing age after the spray method. For the parent birds La Sota strain vaccine was used also--twice after the spray method, plus a vaccine of the strain Komarov--twice intramuscularly and as aerosol (scheme C) and the vaccine strain La Sota spray and aerosol alone (scheme D). Immunity induced in birds after immunization was followed serologically by the titre of serum antihaemaglutinins and by provocation with a highly virulent pseudo-pest virus strain. The 4 schemes of immunization tested comparatively ensure solid immunity of birds to pseudo-pest. Better production index results were obtained from broiler chickens vaccinated after scheme B and parental form birds vaccinated after scheme C.