Serological response of broiler breeders vaccinated postmolt and their progeny: reovirus and infectious bursal disease

When necessary, primary breeders and integrators molt broiler breeder hens to induce a second laying cycle. To protect breeders against Newcastle and bronchitis and provide progeny with maternal antibodies against reovirus (REO) and infectious bursal disease (IBD), it is common to immunize them prior to the first laying cycle with a 4-way inactivated vaccine. The objective was to determine if molted breeders require additional vaccination to increase their antibodies against IBD and REO and those of the progeny. Ross 308 AP (Aviagen) hens of 63 wk of age were molted by providing 100% ground soybean hulls for 10 d. At 9 wk postmolt, half were vaccinated with a 4-way vaccine and half remained unvaccinated. One wk after vaccination, YP males of 26 wk of age were introduced to the hen pens. Hen titers were measured premolt, prior to vaccination, and 3 wk postvaccination. Chicks were hatched from both treatment hens. Vaccination slowed the BW gain of breeders (P ≤ 0.087) and egg production onset (P ≤ 0.095), although egg production was similar between groups at the end of the study (P = 0.230). Molted hens had 34, and 32% less IBD and REO titers respectively compared to premolt samples (P < 0.001). Vaccinating molted hens increased IBD titers by 81% compared to those unvaccinated (P < 0.001). Maternal vaccination increased progeny titers by 242 and 120% for IBD and REO, respectively (P < 0.001) and reduced early mortality during incubation (P = 0.021). In conclusion, it is recommended to re-vaccinate molted breeders to increase both hen and progeny IBD and REO antibodies.