Field Assessment of an Immune-Complex Infectious Bursal Disease Vaccine in Chicks Born to Non-Hyperimmunized Broiler Breeders

Prevention of infectious bursal disease (IBD) remains of paramount importance, given the dramatic losses it can induce in commercial chicken flocks. In the Netherlands, maternal immunity is regarded as low, because the parent stock flocks do not receive an inactivated vaccination prior to the onset of production. Therefore, the aim of this field study was to assess the consequences of hatchery vaccination against IBD using an immune-complex vaccine in broiler chicks that were provided with a limited amount of passive immunity. Three grow out cycles in two houses each (six flocks) were monitored after vaccination. The recorded parameters included (i) body and bursa weight, (ii) IBD antibody response, and (iii) histopathology and PCR from the bursa of Fabricius. Average growth was similar in all groups, although inferior to the breed’s standards. Average bursa weight faced some reduction as part of vaccine effect. Histopathology analysis of the bursa showed a transient inflammatory process, while PCR detected the vaccine strain only. Lastly, serology tests confirmed the successful immunization of all broiler flocks.