Dietary lentinan improves growth, haemato-biochemical indices, resistance to Streptococcus agalactiae infection and expression of immune genes in Asian seabass, Lates calcarifer

Disease outbreak is the single major factor that causes high mortality and substantial economic losses in the farming of Asian seabass, Lates calcarifer. Strategies to improve the health of fishes using prophylactics is considered effective and safe over the use of chemicals and antibiotics. Lentinan is a beta-glucan obtained from shiitake mushroom (Lentinula edodes), known to possess immunomodulatory properties. In this study, juvenile L.calcarifer (average weight 3.36 +/- 0.3 g) were fed with isolipidic and isonitrogenous diets supplemented with lentinan at graded levels viz., 0.0% (C), 0.5% (T1), 1.0% (T2), 1.5% (T3), and 2.0% (T4) for 60 days. Weight gain, Feed Conversion Ratio (FCR), haemato-biochemical indices viz., hemoglobin, white blood cells, packed cell volume, erythrocytes, glucose, cholesterol, triglyceride, expression of growth and immune genes in L. calcarifer were assessed. Lentinan supplemented at 1.5% (T3) significantly (p < 0.05) improved feed utilization, growth performances, disease resistance and expression of growth and immune genes compared to the control. The dietary supplementation of lentinan (0.5% - 2.0%) significantly (p < 0.05) improved the haemato-biochemical indices, survival rates and disease resistance when challenged with Streptococcus agalactiae (LCR1/SRLAAH/2022) at 1.45 x 10(3) cells/fish when compared to the control. The findings of this study demonstrate that lentinan supplementation at 1.5% significantly improves the growth, haemato-biochemical parameters, disease resistance and expression of growth and immune genes in L.calcarifer. Therefore, dietary supplementation of lentinan could be used to improve the overall health and disease resistance in L. calcarifer.