Concomitant day-old subcutaneous herpesvirus of turkey-infectious bursal disease vector and killed + live ND vaccination: protection against a very velogenic Newcastle disease challenge in broilers

Perozo Francisco, Marcano Rosmar, Rojo Francisco, Fernandez Rafael, Lemière Stéphane



Hatchery vaccination protocols in day-old chicks are designed to provide early priming and protection against several poultry diseases including, but not limited to Marek's disease (MD), lnfectious Bursal disease (IBD) and Newcastle Disease (ND). The constraint of concomitant subcutaneous (SQ) administration of MD and IBD vaccines plus ND inactivated in oil adjuvant vaccines (IOAV) in 1-day-old chick and the stringency of field challenges in endemie areas has triggered improvements in vaccine technology. Single needle concomitant SQ application of IBD/MD and killed ND together with the use of viral vectors is a current trend in the industry. This work aims to assess the efficacy of adding live SQ ND vaccine, AVINEW strain, to the hatchery protocol in broilers challenged with a vvNDV. Four groups of 30 one-day-old commercial broilers were used. Group 1: SQ vector HVT-IBD and IOAV plus live ND spray vaccination at the hatchery with two (eight and 18 days) field boast (standard protocol). For groups 2 and 3, SQ live ND vaccination was included at day 1 with and without boast, respectively. The last group remained as unvaccinated control. Ali birds where challenged at 28 days with a lethal dose of a Venezuelan genotype VIl ND virus. Serological response and percentage of survival were used as efficacy criteria. Significantly higher (P<0.05) ND antibody titers at the challenge age were observed when SQ live ND vaccine was added to the standard vaccination protocol. Ali vaccinated birds survived and the control group died within five days after challenge. No adverse effects were observed with concomitant day-old SQ HVT-IBD and killed +live ND vaccination. Adequate protection levels and differences in serological responses suggest the suitability of including the A VI NEW strain SQ vaccination for endemie a reas with high field challenge.