Multivalent inactivated virus oil emulsion vaccines in broiler breeder chickens. I. Newcastle disease virus and infectious bursal disease virus bivalent vaccines.

Inactivated Newcastle disease virus (NDV) and infectious bursal disease virus (IBDV) were incorporated into water-in-oil emulsion vaccines alone or as a bivalent vaccine. Twenty-week-old broiler breeder chickens that had received previous live virus vaccination with NDV and IBDV were injected intramuscularly with the monovalent or bivalent vaccine. The antibody titers to either the monovalent vaccine or bivalent vaccine increased rapidly and then remained at high levels for the duration of the 40-week trial. There were no practical differences in amplitude or duration of the antibody response to either antigen used alone compared to that of the bivalent combination. Progeny hatched from the vaccinated breeders possessed maternal antibody levels at one day of age comparable to those of the hens at the time the eggs were laid. The maternal antibody titers declined at a steady rate until they reached negligibly detectable levels at approximately 3 weeks of age. This trend held true without regard to the initial antibody titer.