Immunomodulatory and growth promoting effect of dietary levamisole in cyprinus carpio fingerlings against the challenge of aeromonas hydrophila

In order to determine the immunomodulatory effect of dietary intake of levamisole in the common carp, specimen were fed diets containing 0 (control), 125, 250 and 500 mg levamisole kg ^-1 of dry diet for a period of 70 days. Experimental stock was challenged intra-peritoneally with Aeromonas hydrophila on 30 ^th and 58 ^th day. Hematobiochemical parameters were determined on day 0, 57 and day 70. The total erythrocyte count, haemoglobin content, hematocrit value, total serum protein, albumin and globulin content were significantly (P<0.05) enhanced in levamisole supplemented groups particularly in 250 mg kg ^-1 group; however the TLC was significantly (P<0.05) higher in control (infected) group. Lysozyme activity and NBT assay were significantly stimulated in levamisole supplemented groups displaying the highest value in 250 mg kg ^-1 group on day 57. After the stock in all the groups had been challenged intra-peritoneally with Aeromonas hydrophila on 30th and 58 ^th day, the relative percentage survival was significantly higher in 250 mg kg ^-1 group (89.6%), followed by 500 mg kg ^-1 group (81.3%) and 100 mg kg ^-1 group (47.9%). Specific growth rate (SGR) was significantly (P<0.05) the highest in 250 mg kg ^-1 group (2.67%) and the lowest in control group (1.82%) and feed conversion ratio (FCR) value was found to be the best in 250 mg kg ^-1 group (1.81), followed by 500 mg kg-1 group (1.85), 100 mg kg ^-1 group (2.02) and control group (2.32). The findings of the present investigation suggest that the incorporation of levamisole in the diet of co mmon carp fingerlingscertainly enhances the non-specific immunity, increases their resistance to infection, and reduces the mortality and enhances the growth of fish.