The Detrimental Effect of Vaccinating Parentally Immune Broilers with a Modified Live Virus Vaccine for Infectious Bursal Disease

Abstract

The experiment involved 392,955 broilers from breeders vaccinated with a commercially available killed infectious bursal disease (KIBD) virus vaccine (Treatments 1 and 2) and 373,371 broilers from breeders not vaccinated with a KIBD virus vaccine (Treatment 2). The broilers from the KIBD-vaccinated breeders were divided into two treatment groups: Treatment 1 consisted of 209,457 broilers and Treatment 2 consisted of 183,498 broilers. Treatment 2 broilers were vaccinated at 10 days of age intraocularly with a commercially available modified liver infectious bursal disease virus (IBD-MLV) vaccine. Broilers in all three treatments were raised on commercially contracted farms serviced by the same company representative. Broiler performance was based on mortality, body weight, feed efficiency, condemnations, and how each farm ranked with respect to contract settlements. Compared with birds in Treatments 2 and 3 respectively, Treatment 1 broilers had 1.65% and 0.89% less mortality; 0.22 lbs. and 0.09 lbs. increased weight per bird; 0.03 and 0.03 increased feed efficiency; 0.09% and 0.32% fewer air sacculitis condemnations; and 0.57% and 0.83% fewer total condemnations. Treatment 1 broilers ranked in the top 37%; Treatment 2 ranked in the bottom 36%; and Treatment 3 ranked in the lower 57% of contract settlements for all broilers processed. The results clearly showed that Treatment 1 broilers outperformed Treatment 2 amd 3 birds and that the IBD-MLV vaccine had a detrimental effect on Treatment 2 broilers.

The efficacy of live infectious bursal disease vaccines in commercial 10 days old chicks.

“…Both mild and intermediate live vaccinal strains of IBDV are neutralized by maternal antibodies (Rinaldi et al, 1974;Winterfield and Thacker, 1978;Weyth and Chettle, 1990;Tsukamoto et al, 1995), but the intermediate strain vaccines are superior to mild vaccines in induction of immunity in the presence of maternal antibodies (Mazzariegos et al, 1990). Chicks with high maternal immunity may require hot IBDV strain vaccines to induce active immunity (Winterfield et al, 1980); however, this strain can induce immunosuppresssion (Thronton and Pattison, 1975;Muskett et al, 1979;Henry and Williams, 1980;Thangavelu et al, 1998). Chicks with low or no maternal immunity can be protected by using live mild or intermediate IBDV vaccinal strains (Solano et al, 1986).…”