Abstract
This study was conducted to assess the effect of methanolic plant extract of some selected plants (Acanthus montanus, Spondia mombins and Mucuna pruriens) on immune response in cockerel. One hundred and forty birds were allotted to 7 groups (n=10) in this experimental unit and replicated twice. Birds were administered Spondias mombin orally at 250mg/kg bw, Spondias mombin at 500mg/kg bw, Mucuna pruriens at 250mg/kg bw, Mucuna pruriens at 500mg/kg bw, Acanthus montanus at 250mg/kg bw, Acanthus montanus administered orally to birds at 500mg/kg bw and distilled water and designated as Groups 1-7 respectively. Birds were vaccinated against Gumboro twice at days 10 and 21 while Lasota vaccine was administered twice at days 14 and 28. Blood samples were collected brachial vein (wing vein) of the animal on days 9, 23 and 37 to obtain sera samples which were used for indirect haemagglutination assay (IHA) (Gumboro) and days 13, 27 and 42 for sera samples used for Haemaglutination inhibition test (HI) (Newcastle). There were no significant differences (p>0.05) in the initial antibody titre among the birds for both IHA and HI. The highest antibody titre, 28.0 was found in birds administered with Acanthus montanus (500mg/kg) at day 42 for HI. The highest antibody titre for the IHA was found in birds administered with Acanthus montanus (500mg/kg) at day 37. The control birds had 23.5 and 23.7 at days 37 and 42 for IHA and HI respectively.From this study, A. montanus at 500mg/kg is recommended as adjuvant to gumboro and Newcastle vaccines in poultry.

Key words: Gumboro, Newcastle, Vaccine, IHA, HI, medicinal plants