Effects of Poria cocos polysaccharide on growth performance, physiological parameters, and lipid metabolism of spotted sea bass Lateolabrax maculatus

The aquaculture industry has developed significantly over the past few decades and has had a substantial impact on the global food supply and marine fisheries resources. However, some problems arise behind the scenes due to excessive intensive farming, such as slow animal growth, frequent disease, and lipid metabolism disorders. These problems have limited the sustainable development of the aquaculture industry, and a continuable solution is required. The use of fungal polysaccharide appears to provide a solution to these problems. Therefore, different supplemented levels of Poria cocos polysaccharide (PCP) (0, 0.4, 0.8, 1.2, 1.6, and 2.0 g/kg, respectively) were fed to spotted sea bass (Lateolabrax maculatus) in similar size (30.28±0.18 g) in current study. The effects of PCP on growth, physiological parameters, and lipid metabolism of spotted sea bass were investigated after a 4-week rearing period. Results showed, fish with PCP intake presented a significantly higher weight gain, specific growth rate, and a significantly lower feed conversion ratio. Significantly higher trypsin activity in liver and intestine were observed in fish with PCP intake. The superoxide dismutase activity in serum and liver of fish with PCP intake were significantly improved, while significantly higher serum total antioxidant capacity and hepatic catalase activity were also observed. However, no significant differences in lysozyme and alkaline phosphatase activity were evident among groups. Fish with PCP intake showed a significantly lower total cholesterol, but no noteworthy change in triglyceride and lipid-metabolism-related genes expression were observed among groups. Results indicated that intake of PCP has a positive effect on growth and antioxidant capacity of spotted sea bass, but seems to have a limited effect on the non-specific immunity and lipid metabolism of spotted sea bass. Based on the regression analysis results, 1.4 g/kg of PCP is the optimal dose for spotted sea bass in size (30.28±0.18 g).