Response of Village Chickens to Newcastle Disease (ND) Vaccine with Broken Sorghum as the Vehicle

Abstract

The suitability of sorghum as carrier for Newcastle Disease (ND) V4-UPM virus vaccine for vaccination of freerange chickens was assessed by standard methods. The grain was ground rough or broken, soaked in water for three days, washed, sun-dried, coated with the virus and finally dried at room temperature. The food vaccine which was supplied to chicken owners in two different locations was fed to the birds in their natural habitat. Blood for serum was collected two weeks after each feeding event for haemagglutination inhibition (HI) assays. Samples of vaccinated and unvaccinated chickens were bought back from owners and exposed to velogenic strain of ND virus. Results showed that out of 129 birds
vaccinated, 87 (67.4%) propduced detectable HI antibody with only 13 (10.1%) attaining antibody level of log2 > 3.0 regarded as protective and geometric mean titre (GMT) of 3.1 after primary vaccination. After a booster dose on 116 birds in the same flock, 95 (81.9%) seroconverted with 67 (57.8%) attaining log2 > 3.0 and GMT of 11.8. Exposure of 34 vaccinated buy-back and 25 unvaccinated (control) chickens to velogenic challenge virus led to 26 (76.5%) chickens and 4 control birds (16.0%) surviving respectively. Sorghum, if adequately treated could be a suitable carrier for thermostable ND vaccines, and as dried food vaccine, it could have good shelf life at room temperature.