Objectives: This experiment was conducted to investigate the effects of peppermint extractin on chicks receiving SRBC on immune responses. Materials & Methods: in a afactorial design with 4 treatments and 4 replicates of 10 chicks per replicate.Treatment 1 was the control group fed with basal diet, treatment 2 received basal diet with 450 ppm AGP, treatment 3 the basal diet with 0.1 % of the peppermint extract and treatment 4 basal diet with 0.2 % of peppermint. In this study, in 28 and 35 days of age, 0.5 ml SRBC per each bird was injected in the right chest muscle and on days 35 and 42 of each replication, two blood samples were taken to in vestigation Immune responses. Results & Conclusion: The results showed that improvement immune response against Newcastle disease was obtained in treatment 4 receiving 0.2 percent peppermint exteract-dose at 42 days of age. Immune respons of influenza in birds of different treatments showed no significant improvement (P>0.05).
