Effects of Sargassum Polysaccharide on the Growth Performance,Blood Biochemical Indicators and Immune Regulation of Tilapia Oreochromis aureus ♂× Oreochromis niloticus ♀

[Objective] The research aimed to investigate the effects of sargassum polysaccharide(SP)on growth performance,blood biochemical parameters and immune-regulatory in the tilapia Oreochromis aureus ♂×Oreochromis niloticus ♀.[Method] The tilapia Oreochromis aureus ♂×Oreochromis niloticus ♀ were fed with control diet and three different experiments diets which contain 0.1%,0.15% and 0.2% sargassum polysaccharide(SP)levels by oral administration.And the weight gain ratio,specific growth rate,formulated feed index,blood biochemical parameters and non-specific immune indicators were analyzed after 30 d.[Result] Compared with the control group,the weight gain ratio,specific growth rate of the tilapia fed with 0.1% sargassum polysaccharide were increased significantly(P0.01) and the formulated feed index decreased significantly(P0.01).And the red cell number,the concentrations of total protein and serum glucose in the blood were increased significantly(P0.05) when the tilapia were fed with the experiment diet contained 0.1% SP.The concentrations of total protein,enzymes activities of lysozyme,SOD,and ACP in blood of the tilapia were both increased observably(P0.05) by treatment of diets which contains 0.15% SP.0.1% SP can not only significantly(P0.01) enhance the concentrations of total protein and the enzymes activities of ACP but also significantly(P0.05) enhance the enzymes activities of lysozyme in blood of the tilapia.[Conclusion] SP could improve the growth performance and the non-specific immune function of the tilapia Oreochromis aureus ♂×Oreochromis niloticus ♀ observably.The best concentration of SP was 0.1%-0.15% when it was added in the feed diet of the tilapia Oreochromis aureus ♂×Oreochromis niloticus ♀.