Vaccination Strategies in Breeder and Commercial Farms and Infectious Bursal Disease Maternally Derived Antibodies in Day Old Chicks in Nigeria
In Nigeria infectious bursal disease (IBD) outbreaks have persisted despite routine vaccination. In a quest to determine some of the causes of the vaccination failures, the type of vaccines, vaccination schedules and seromonitoring for antibodies in breeder and commercial farms were investigated using structured questionnaires. The presences and level of maternally derived antibodies in broiler and layer day old chicks from four and six breeders respectively was determined using enzyme linked immunosorbent assay (ELISA) test. Based on the level of antibodies in day old chicks the central vaccination times and vaccination days were calculated using the Deventer formula. Not all breeder farms monitor for antibodies in breeders or chicks and only one of the 17 commercial farms sampled monitor for antibodies in chicks. The type of vaccines used and schedules vary with breeder farm. All broiler and layer commercial farms vaccinate with intermediate vaccine at 5 or 12 and 17 or 22 days of age. The mean IBD maternally derived antibodies (MDA) ELISA titre of day old broilers ranged from 1,564+873 to 2,472+962 while the titre was 2,015+1133 to 3,415+1958 for layers depending on breeder farm. Only the coefficient of variation of the MDA titre of day old chicks from two layer breeders was uniform (less than 30%). The calculated vaccination days using intermediate IBD vaccine for broilers was 14 and 20 days and 26 and 32 days for layers. About 2% to 24% of day old broilers and 2% to 16% layers had IBD MDA ELISA titre below 1,000. Based on the IBD MDA ELISA titre and %CV there is a need to harmonized and improve the vaccination strategies in breeder and commercial farms but breeders and day old chicks should meanwhile each should be seromonitored to determine the best time to vaccinate. In the absence of seromonotoring it is recommended that commercial farmers vaccinate broilers with intermediate at 14 and 20 days of age and layers with intermediate-plus IBD vaccine at 14 and 20 days of age in addition to instituting effective biosecurity to reduce the chances of exposure to IBDV early in life with resultant immunosuppression.
Keywords: Farms, infectious bursal disease, maternal antibodies, vaccination