Effects of dietary crude polysaccharides from Lycium barbarum on growth performance, digestion, and serum physiology and biochemistry of spotted sea bass Lateolabrax maculatus

High-quality development requires the aquaculture industry to reduce the use of chemicals and further improve feed efficiency, while the use of Lycium barbarum polysaccharide (LBP) is one of a potential way to achieve it. The current study was conducted to investigate the effects of dietary LBP on growth performance, digestion, antioxidant capacity, hepatic and intestinal morphology, and serum lipids of spotted sea bass, Lateolabrax maculatus. A total of 450 spotted sea bass (20.64 ± 0.18) g were assigned to 18 tanks. Three tanks were defined as a group, and fish in each group were given diets with increasing level of LBP (0, 0.25, 0.50, 0.75, 1.00 and 1.25 g/kg) for 49 days, respectively. Results showed that dietary intake of LBP significantly improved the weight gain, specific growth rate, feed conversion ratio, amylase activity and lipase activity of spotted sea bass. However, no significant effect of LBP on fish superoxide dismutase, malondialdehyde and catalase was observed. Dietary LBP alleviated ballooning degeneration and fat vacuoles in fish liver. However, mild inflammation was observed in 1 g/kg LBP group fish liver. Dietary LBP significantly increased the high-density lipoprotein cholesterol level of fish, and reduced the total cholesterol and low-density lipoprotein cholesterol level. The expression of hepatic FAS and SREBP-1 were significantly down-regulate, and the expression of PPAR-α, CPT1, HSL, ATGL and LPL were significantly up-regulated by dietary LBP. This result reminder that dietary LBP may inhabit the synthesis of fatty acid, and promote the fatty acid oxidization and triglycerides hydrolyzation. In conclusion, dietary LBP improved growth performance, digestion, hepatic morphology, and serum biochemical parameters of spotted sea bass in size (20.64 ± 0.18) g. The optimal addition of LBP for spotted sea bass is about 1 g/kg based on the regression analysis.