Newcastle disease (ND) outbreaks have been reported in vaccinated poultry flocks in Nigeria and this highlight the need for administration of immunostimulants to improve immunity in such birds. The immunomodulatory effects of Mentofin® (a recent introduction into Nigeria) and Levamisole on antibody response of vaccinated chicks against ND were assessed. One hundred day-old chicks were randomly divided into five groups (A-E). Group A: unvaccinated; B, C, D and E: were administered LaSota vaccine at 14 and 42 days old. In addition, group C received Levamisole, group D received Mentofin® and group E, received a combination of Levamisole and Mentofin® orally for 3 days consecutively post-vaccinations. Blood samples were then collected from each group. ND virus antibody titers were determined using ELISA. Maternal antibody titre (76.55±2.35) at day-old declined at 56 day-old (3.83±0.3-7) in group A. At 14 days post primary vaccination, peak antibody titres in groups C, D and E (62.3±4.51, 60.2±3.84 and 64.9±5.58) were significantly higher than that of group B (42.3±4.28). Also, at 14 days post-secondary vaccination, peak titre in group E (77.9±3.14) was significantly higher than in groups A, B, C and D (3.83±0.37, 44.0±3.20, 71.1±3.48 and 70.3±3.25). This study shows that oral administration of Mentofin® and Levamisole significantly enhanced humoral response to live ND vaccination and their combination has a synergistic effect.
Key words: Levamisole,Mentofin, Broiler, Antibody response, Newcastle disease vaccination.