Effect of Ocimum sanctum Linn. (Tulsi) extract on the immunity and survival of Labeo rohita (Hamilton) infected with Aeromonas hydrophila

摘要

A 60days study was conducted to evaluate the efficacy of water extract of Ocimum sanctum Linn. leaf on the immune response and disease resistance of Labeo rohita fingerlings against the Aeromonas hydrophila infection. Ocimum sanctum extract was incorporated in the diets (at 0.0%, 0.05%, 0.1%, 0.2%, 0.5% and 1%) of Labeo rohita, rohu fingerlings (6.6 +/- 0.013g). After 42days blood, plasma and serum were sampled to determine super oxide anion production, lysozyme activity, total immunoglobulin in plasma, blood glucose, serum total protein, albumin, globulin, albumin:globulin ratio, WBC, RBC, haemoglobin content. Fish were challenged with A. hydrophila after 42days and mortalities were recorded over 18days post infection. The results demonstrate enhanced super oxide anion production, lysozyme activity, total immunoglobulin in plasma, serum total protein, globulin, total RBC counts, total WBC counts and haemoglobin content (P<0.05) in treatments group compared with control group. Dietary O. sanctum extracts of 0.2% showed significantly (P<0.05) higher protection relative percentage survival (RPS 40.00 +/- 5.773%) against A. hydrophila infection than control. These results indicate that O. sanctum leaf extract stimulates the immunity and makes L. rohita more resistant to bacterial infection (A. hydrophila).