Immunomodulatory activity of Pinus radiata extract (PRE) against experimental Eimeria infection in broiler chicks was evaluated. For in-vivo trials, 175 day-old broiler chicks were divided into five equal groups (A, B, C, D and E) containing 35 chicks in each group. At one week of age, the groups A, B and C were given orally with graded doses of PRE (100, 200 and 300 mg/kg of body weight, respectively) for three consecutive days. Group D served as positive control (Vitamin-E treated) and Group E served as negative control (PBS treated). At 14^th day of age, all groups were infected orally with 60,000 sporulated oocysts of mixed Eimeria species. Cell mediated immune response was evaluated by Phytohemagglutinin-P, Concanavalin-A, Carbon clearance assay and Dinitrochlorobenzene tests. Humoral immune response was evaluated by microplate hemagglutination test using sheep red blood cells. Results of study demonstrated that a dose dependent immune response was observed in PRE treated groups. Cell meditated and humoral immune response of group treated with PRE @ 300 mg/kg of body weight was comparable to positive control group (Vitamin-E treated) (P˃0.05). Pinus radiata extract treated groups showed significantly higher cell mediated and humoral response as compared to negative control (PBS) (P<0.05).

Key words: Coccidiosis, Eimeria, Immunity, Pinus radiata extract