Abstract

Thermostable Newcastle disease vaccine virus strain I2 (NDVI₂) was investigated for its efficacy as foodborne vaccine using maize, sorghum and their brans as carriers. Immune response to vaccination and resistance to challenge were assessed by haemagglutination inhibition (HI) test. After primary and secondary vaccination at three and six weeks of age, sera and feather pulp samples were analyzed to determine the antibody titre in the different groups. The highest mean antibody titre of 7.39 ± 0.42 log₂ was recorded for serum when the vaccine was administered through treated sorghum coated with gum Arabic (TSGG) and 7.28 ± 0.37 log₂ for feather pulp in the group given maize bran (MZB) at eight weeks of age. There was no significant difference (p ˃ 0.05) between the HI antibody titre in the feed groups from feather pulp samples at three weeks of age while a significant difference (p < 0.05) in the serum antibody titre was observed between all the feed groups at five weeks of age. There was correlation in antibody titre between serum and feather pulps only at two weeks after second vaccination. The protection rate after challenge in all the groups was low with the highest rate (14%) recorded when the vaccine was administered in treated maize (TMZ) and TSGG. The study concluded that the vaccine could be effective for the protection of village chickens as food-borne vaccine provided the carrier foods are adequately treated to remove antiviral agents. The use of feather samples as suitable alternative to serum for ND serology was discussed.

Key words: Chickens, maize, sorghum, Newcastle disease, thermostable vaccine.