Innate Immune Response and Growth Performance of Heterobranchus longifilis Catfish Juveniles Following Dietary Aflatoxin B1 Exposure

We evaluated the effects of dietary aflatoxin B1 (AFB ) exposure on the immune response and the 1 growth performance of Heterobranchus longifilis catfish; and determined the maximum tolerable limits for AFB in H. longifilis. Five experimental isocaloric and isonitrogenous diets amended 1 with varied concentrations of AFB [Diet A (2.0 μg AFB .kg-1); Diet B (7.3 μg AFB .kg-1); Diet C 1 1 1 (17.6 μg AFB .kg-1); Diet D (48.0 μg AFB .kg-1) and Diet E (93.0 μg AFB .kg-1)] were fed to 450 1 1 1 juvenile H. longifilis in five groups of 15 separate plastic tanks for a period or 56 days. At time points day 7, 14, 28 and day 56, five fish were randomly sampled per tank and assessed for innate immunity and growth response. Fish fed diets amended with AFB exhibited significant reduction 1 (P < 0.05) in the serum lysozyme and epidermal mucus lysozyme activity, epidermal mucus alkaline phosphatase activity and in the phagocyte respiratory burst activity. These parameters decreased with increasing concentrations and duration of dietary AFB (P< 0.05). Dietary AFB 1 1 caused significant reductions in the growth performance of juvenile H. longifilis marked by reductions in the percentage gain in length, reduction in percentage gain in weight and a reduction in the specific growth rate. Based on these results, juvenile H. longifilis catfish appears to tolerate diets containing up to 17.6 μg. Kg-1 AFB in diets.