One hundred and twenty, one week old, Cobb 400 broiler chickens were randomly distributed into three dietary treatments having four replicates each with ten birds. The birds of the control group (T1) were fed a basal diet (23.16% CP 1-3 weeks & 19.68% CP 3-6 weeks) while the other two groups were offered the treatment diets (T2& T3) replacing 4.50% or 5.50%, of the dry matter of the basal diet with dry Azolla pinnata powder on dry matter basis, respectively. Feeding azolla meal did not significantly (p>0.05) affect the weekly body weight gain of the birds during the experimental period. Total immunoglobulins and mercaptoethanol sensitive (IgM) antibody titer (log 2) values in response to sheep red blood cells (SRBC) was significantly higher (P<0.05) in the birds fed T3 diet compared to the other two dietary treatments at 6 weeks of age. Cell mediated immune response i.e. in vivo cutaneous basophilic hypersensitivity response to lectin phytohaemagglutinin from Phaseolus vulgaris (PHA-P) determined as foot web index was significantly (p<0.05) higher in the T3 birds compared to the other two dietary treatments. Dressing percentage was significantly higher (P<0.05) in T2 compared to the other two treatment groups.

However, there was no significant difference among the treatment groups in the other carcass traits. Thus, it may be inferred that replacement of basal diet with dry Azolla pinnata meal on dry matter basis did not adversely affect the growth and carcass characteristics. Moreover, Azolla pinnata possesses promising immunomodulatory potential in commercial broilers.