Protection situation for Newcastle disease after vaccination in industrial chicken farms in Dong Nai province

Abstract

The study aimed at investigating the situation of the industrial chicken farms in Dong Nai
province, evaluating the efficiency of Newcastle vaccine, and determining the potential factors
affecting the protective ability of Newcastle vaccine in the farms. In 2015-2016, a total of 10,463
blood samples were collected from 283 chicken farms, 21 days after Newcastle vaccination in 10
districts of the province. In the surveyed farms, there were 133 farms for meat production, 111
farms for egg production and 39 farms for chicken breeds. The serum samples were tested for
Newcastle antibody after vaccination by using HA and HI. In 283 surveyed farms, the proportions
of large farms (> 20,000 chickens), medium farms (5,000-20,000 chickens) and small farms (<
5,000 chickens) accounted for 56.5%, 37.1% and 6.4%, respectively. The highest proportion of
getting protection (protective level ≥ 80% per herd) was observed in medium farms. Chickens
farms for egg production and chicken breeds showed more than 95% protective rate after
vaccination and the period of vaccination in the year might not influence the protective rate of
Newcastle vaccine. The logistic model showed that the geographical location of industrial chicken
farms and production type could affect the protective rate of Newcastle vaccine.