枸杞多糖和海藻多糖对虹鳟鱼幼鱼生长、免疫和肝脏脂质代谢的不同影响

Polysaccharides play crucial roles in medicine and nutrition, serving as dietary additives that help maintain fish health. This study systematically evaluated the effects of dietary supplementation with plant-derived Lycium barbarum polysaccharides (LBP) and Seaweed-derived polysaccharides (SPs) on growth, metabolism, and immune function in rainbow trout (Oncorhynchus mykiss). A total of 270 juvenile rainbow trout (15.50 ± 0.71 g) were randomly divided into three groups (control group, CG; 1.5 g/kg LBP; 1.5 g/kg SPs), with 90 fish in each group. The feeding trial lasted 56 days, with sampling at days 28 and 56. Compared with CG, SPs increased WGR by approximately 39.4%, decreased FCR by approximately 44.7%, and elevated muscle Ala, Glu, and Gly contents. SPs also improved intestinal microbiota balance and promoted the synthesis of amino acids and short-chain fatty acids (SCFAs). In addition, SPs significantly enhanced CAT and SOD activities and upregulated IL-10 expression by approximately 2.3-fold. Compared with the CG, LBP can reduce the total cholesterol content by 33.3%, inhibit lipid synthesis, and promote fatty acid oxidation. It also upregulates the expression of the PPARα gene by approximately 2.4-fold. In the Aeromonas salmonicida challenge test, survival rates of the SPs and LBP groups were 30% and 20% higher, respectively, than that of CG. These results indicate that SPs were more effective in promoting growth and enhancing immunity, whereas LBP showed superior performance in metabolic regulation. This study provides a basis for the targeted application of these two substances.