Efficacy of Different Vaccination Programs against Velogenic Newcastle Disease Virus Challenged in 28-day-old Broiler Chickens

Abstract

In the present study, the efficacy of different vaccination programs against a velogenic Newcastle disease virus (vNDV) challenged in 28-day-old broiler chickens was examined. The chickens were divided into 5 groups, 20 chickens in each. Group 1 did not receive any vaccine and served as the non-vaccinated control group. Groups 2-5 were vaccinated with different vaccination programs against vNDV. At 1-day-old, the chickens in all the vaccinated groups were vaccinated with live Newcastle disease (ND) vaccine, Ulster 2C strain, followed by different inactivated vaccines including vaccine A in groups 2 and 4 and vaccine B in groups 3 and 5. At 7-day-old, revaccination was performed in the vaccinated groups including live vaccine, Ulster 2C strain, in groups 2 and 3 and live vaccine, B1
strain, in groups 4 and 5. Finally, the chickens in every group were challenged with vNDV at 28-day-old. Results showed that NDV HI titer at the challenge inoculation time of all the vaccinated groups was significantly higher (p < 0.05) than that of the non-vaccinated group. At 14 days post-inoculation, mortality rate of the vaccinated groups was significantly lower (p < 0.05) than that of the non-vaccinated group. Body weights of all the vaccinated groups were significantly (p < 0.05) higher than those of the non-vaccinated group. The results indicate that all the vaccination
programs used in this study could alleviate body weight loss and protect the chickens from lethal infection with vNDV.