Effect of Dietary Ganoderma lucidum Polysaccharides (GLP) on Cellular Immune Responses and Disease Resistance of Yellow Catfish (Pelteobagrus fulvidraco)

Abstract

This study investigated the effects of dietary Ganoderma lucidum Polysaccharides (GLP) on cellular immune responses and disease resistance in yellow catfish (Pelteobagrus fulvidraco). For 8 weeks, 540 yellow catfish were fed different levels of GLP. The treatments were: 0-control group, 300-T1, 600-T2, 900-T3, 1200-T4, 1500-T5 mg/kg, respectively. After the 8 week feeding trial, the respiratory burst activity of head kidney macrophages, proliferation of peripheral blood leukocytes, and phagocytic activity were assayed. Both the control and treated groups of fish were then challenged with an intraperitoneal injection of Aeromonas hydrophila, and cumulative mortality was recorded for 6 days post-infection. Results showed that there was a significant increase in oxygen respiratory burst activity of head kidney macrophages (p<0.01), along with significant increases in proliferation of peripheral blood leukocytes (p<0.01) in the fish fed dietary GLP. In addition, the 1200-T4and 1500-T5 mg/kg groups also displayed significant increases in nitrogen respiratory burst activity (p<0.01). These data indicated that GLP may reduce mortality following A. hydrophila infection. The lowest mortality was observed in the T5-treated groups. In conclusion, dietary GLP may effectively enhance cellular immune responses and disease resistance in yellow catfish against Aeromonas hydrophila.