The Thai Journal of Veterinary Medicine


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.


Faculty of Veterinary Science, Chulalongkorn University

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