Hyperimmunisation of Breeders
Parent breeder chickens are hyperimmunised against IBDV. (Immune system is boosted to achieve a high level of circulating IBDV antibody.) Hyperimmunisation is achieved by priming parents during the rearing phase with a live IBDV vaccine between 4 and 10 weeks of age, followed by an inactivated IBDV vaccine at 16 – 18 weeks of age. The resultant high level of IBDV neutralising antibodies induced in the parent bird is passively transferred to the day old chick via the yolk sac, so called maternally derived antibody (MDA).
This strategy is implemented to protect the young chick during the first one to two critical weeks post hatch. The control of variant IBDV in broilers is achieved by hyperimmunising breeder flocks with inactivated variant IBDV vaccines.