Administration of non activated infectious bursal disease oil-emulsion vaccine to commercial layer chickens at different ages

ABSTRACT

Commercial layer chickens of different ages carrying maternal antibody levels to infectious bursal disease [IBD] were inoculated with a full dose a commercial inactivated oil-emulsion IBD vaccine, and then challenged with very virulent IBD virus [vvIBDV] at 7 and 14 days post-vaccination [PV]. The results revealed complete absence of vaccinal protection [0%] one week PV and poor vaccinal protection [10- 50%] two weeks PV, when vaccination adopted weekly during the period from 7 up to 35 days of age. However, survivors during this period showed bursal lesions and significant [P <0.05] bursal atrophy two weeks PV despite vaccinal protection conferred against mortality