Serological response and protection level evaluation in chickens exposed to grains coated with I2 Newcastle disease virus for effective oral vaccination of village chickens.

Background: Conventional Newcastle disease (ND) vaccination strategies in village chicken production settings is impractical due to shortage of cold-chain, unsuitability of vaccine administration routes and demanding trained personnel and hence affected its adoption. Results from earlier works elsewhere showed that the heat stable vaccines such as NDI2 are thought to be promising for village chickens. This study investigated the suitability and efficacy of Ethiopian cereal grains as carriers for the orally administrated NDI2 vaccine in chickens.

Results: Of the 15 treatment groups, drinking water, cracked maize and parboiled barley induced significantly higher HI antibody titer than the other carrier grains and naive control. The higher mean HI titer of chickens in drinking-water, cracked maize and parboiled barley group resulted in 100 % survival rate. In general, there was an inverse relationship between chicken mortality (%) and mean HI titer. Chickens with higher HI antibody titers had better survival rate to the challenge experiment. Booster vaccination at age of day 35 and 105 induced progressively higher HI antibodies titers in all treatment groups.

Conclusions: Vaccine coated parboiled grains could be a good carrier followed by cracked grains while untreated vaccine carrier grains had lower serological responses and protection levels. The current finding gives insights on suitable vaccine delivery system in villages with weak health and transportation infrastructure, unreliable electricity, and minimally trained health workers without catching chickens individually.