Residual Pathogenic Effects of Infectious Bursal Disease Vaccines Containing Intermediate and Hot Strains of the Virus in Broiler Chickens

Abstract

The detrimental outcomes of intermediate and hot infectious bursal disease virus (IBDV) vaccine strains in broiler chickens were the objective of this study. Carcass weight gain, bursal enlargement and hemorrhage in the muscles were the parameters considered to monitor these effects. Two hundred, day-old broiler chicks were divided into eight groups namely A, B, C, D, E, F, G and H. Chicks in groups A, B and C were vaccinated with intermediate, hot and both vaccine strains of the virus respectively whereas group D left without vaccination as control in closed pens. Chicks in groups E, F, G and H were treated similarly but in open pens. In both systems of rearing, the highest effects of the vaccines on chicks performance was observed for those vaccinated with the hot strain of IBDV, followed by intermediate strain vaccinated chickens and least effect on those vaccinated with the intermediate and boostered with the hot one. The results obtained also showed that chickens reared in closed pens put slightly higher (p<0.05) body weight, low levels of bursal enlargement and relatively low hemorrhage in the muscles as compared to those reared in open pens. As a conclusion and recommendation, it was advised to vaccinate chickens with intermediate strains of IBD at 2 weeks old and booster them with the hot one at 3 weeks in closed systems.