Synergistic effect of Plant Extracts Supplemented Diets on Immunity and Resistance to Aeromonas hydrophila in Mystus keletius

Abstract

Assistant Professor, Dept.of Microbiology, M.S.S.Wakf Board College, Madurai. Associate Professor, Dept.of Zoology, Yadava College, Madurai. ________________________________________________________________________ Abstract: The mixture of two plant extracts ( Solanum trilobatum and Ocimum sanctum) were extracted with 70% ethanol and screened for their antimicrobial activities against Aeromonas hydrophila, a bacterial pathogen. Using disk diffusion assays, equal proportions of plant mixture extract ( mixture of Solanum trilobatum, Ocimum sanctum in 1:1 proportion) were mixed thoroughly with the artificial feeds at concentrations of 0.0 (A), 3 (B), 30(C), 300(D) mg kg of dry diet. The prepared diets were fed to healthy Mystus keletius for 60 days and then challenged with A. hydrophila. The hematological, biochemical and immunological parameters of fish were investigated at 20, 40 and 60 days of feeding and also on 10th day postchallenge in order to evaluate the immune response and resistance against A. hydrophila infection of fish. Results indicated that respiratory burst activity, serum bactericidal activity, lysozyme activity, serum protein, albumin, globulin, WBC, RBC and haemoglobin content were enhanced (p<0.05) in fish fed herbal diets compared to the control group. On 10 days post-challenge, the total survival rates were 38.09% in control group (A) and 72.15%, 80.95%, 85.71% in groups B, C, D respectively. Among different groups, D generally showed the best performance in the experiment. Further research is needed to isolate and characterize the active compounds from these plants.