Abstract
Garlic (Allium sativum), has proven to be an effective growth promoter and immunostimulant in poultry. It`s ability to enhance cellular immune response was investigated using interferon gamma assay. A total of 100-day-old chicks were divided into 4 groups of 20 each in groups A, B, C and 40 in group D which was further sub-divided into subgroups D1 and D2. Feeds served were supplemented with varying levels of garlic meal i.e. Group A- 0.125%, Group B- 0.25%, Group C -0.5%. Group D- 0% (i.e. D1 and D2). Chicks in all groups were administered Newcastle disease vaccine HB1 strain at day-old, Lasota strain at 3-week-old. At 5-week-old, they were all challenged with the Newcastle Disease Virus Komarov strain except subgroup D2. Twelve chicks were selected randomly from each group (A, B and C as well as subgroup D1), Eight chicks were selected from subgroup D2 and were all bled at 6 week-old, sera were obtained for the assessment of interferon-gamma level and data obtained were subjected to statistical analysis using Analysis of variance and Turkey multiple comparison test (Graph Pad Prism) at p<0.05.
Mean interferon-gamma concentrations showed no significant difference (p>0.05) between groups A (151.16±0.46 pg/ml), B (151.30±0.33 pg/ml) and C (152.36±0.26pg/ml) but these values were significantly higher (p<0.05) than those of subgroups D1 (142.33±1.9pg/ml) and D2 (127.13±2.2pg/ml). Also, mean concentration in subgroup D1 was significantly (p<0.05) higher than that of subgroup D2.
The study showed that Garlic has an immunomodulatory effect in commercial chickens via an increased secretion of interferon-gamma, which could be responsible for the reported improvement in vaccinal immune response and its general antibiotic activity.
Key words: Interferon-gamma, Garlic, Cockerels, Cellular Immune Response, Newcastle disease vacci

Key words: Interferon Gamma, Garlic, Cockerels, Cellular Immune Response, Newcastle Disease Vaccines.