ABSTRACT
In this experiment, the effect of consecutive oral levamisole usage on cellular and humoral responses of broilers immune system was evaluated. The aim of this experiment was to determine the best level of levamisole for stimulating immune system of broilers. The experiment was conducted by 250 day old [male and female] broiler [Ross] chicks with an average live weight of 40.2g. Effect of zero [control L0], 3.5 [L3.5], 7 [L7], 14 [L14] and 28 [L28] mg/l of levamisole in drinking water from 5 to 25 days under randomized design using a factorial experiment with 5 replication were studied. Cellular immune responses were assayed by PHA-P injection in the skin fold of wings [day 15] and thickness of skin were measured after 24 and 48 hours. Sheep Red Blood Cell [SRBC] 25% were injected in the breast muscle in days 7 and 21 to investigate humoral immune responses, and IgG titer against SRBC was determined in days 7, 14, 28, 35, and 42 by agglutination test. Cellular immune responses to PHA-P in treatments containing 7 and 14 mg/l of levamisole [0.272 and 0.205, respectively] were significantly affected [p<0.05]. IgG titer against SRBC in treatment containing 14 mg/l of levamisole [6.16] was significantly higher than other groups [p<0.05]. Carcass trait of broiler chicks were not affected by different level of consecutive oral levamisole [p>0.05]. The low level [up to 14 mg/L] of consecutive oral levamisole promotes cellular and humoral immune system responses of broiler chicks