Evaluation Of Infectious Bursal Disease Virus Maternally Derived Antibody Decay Rate In Day Old Broilers From Different Hatcheries In Nigeria

Abstract

Infectious Bursal disease (IBD) is an immunosuppressive disease of young chicks, which is responsible for major economic losses in the  poultry industry worldwide, particularly for the last decades. This study utilized a cross-sectional approach to evaluate Infectious bursal  disease virus (IBDV) maternally derived antibody decay rate in day old chicks (D.O.C) obtained from different hatcheries in Nigeria. Of the  450 serum samples collected through random selection with replacement method, (i.e 90 samples from the 5 hatcheries designated  as farms A – E), it was observed that farm A at day 1 had mean Elisa titre of (4213 ± 366.66), farm B (2178.225 ± 292.477), farm C (1629.699  ± 229.2197), farm D (3452.609 ± 403.64.6469) and farm E (1651.789 ± 201.6811), these values were far above the protective (positive) level  of 875, recommended by IDvet manual with (S/P ratios of 0.350). This level was maintained, although, with minimal decays, up to day 7  for farms A, D and E but farm B and C did not exceed day 6 and day 5 respectively. Only farm D presented protective (positive) value that  lasted to day 13. The best fit for this decay rate was calculated to be Y = -2263In(x) + 3714 (week) with R² = (0.903). From these studies we  could deduce that these farms were truly vaccinated or immunized as expected and they presented different antibody titres with variable  decay rates. It would have been a good idea to recommend that same vaccination schedule should not be applied indiscriminately to  broilers from these farms like other researchers have, but this would rather be to the detriment of many farmers who may not be  privileged to access the detailed information on which schedule is meant for which farm .We therefor recommend that broilers from  these hatcheries be vaccinated between day 7 to day 10 post hatch and a booster dose (if necessary) should be administered a week  after, with an intermediate plus strain vaccine type that has the capacity to penetrate through the MDA and induce humoral-immunity-in- thechicks.