Day-old broilers were administered live and/or
inactivated vaccines to assess
vaccine efficacy against challenge with
Newcastle disease (ND) and infectious bursal disease (IBD). Chicks were from commercial breeder pullets vaccinated against ND and IBD using several live
vaccine primers followed by an inactivated ND-IBD
vaccine at 18 weeks. The most efficacious initial ND-IBD vaccination program was live ND virus by
eye drop and live IBD
vaccine injected subcutaneously (SQ) followed 2 hours later with inactivated ND-IBD
vaccine SQ. The next two most efficacious programs were live
vaccine alone and the
inactivated vaccine only.
Inactivated vaccine given SQ had no adverse effect on live IBD
vaccine given 2 hours earlier in a similar site. Administration of
inactivated vaccine by vent was not as efficacious as administration SQ. A booster of a second live ND-IBD
vaccine drinking water at 18 days significantly increased levels of circulating antibody, regardless of the initial vaccination program.