Strategically using Yupingfeng polysaccharides to improve the growth performance, antioxidant capacity, liver health, and lipid metabolism of largemouth bass (Micropterus salmoides) under a high-lipid diet

Yupingfeng polysaccharide (YPP) is a powerful composite polysaccharide with various potential effects. In this experiment, largemouth bass with an initial weight of 8.7 ± 0.05 g were fed five different diets. These included a normal control group diet (NC) containing 12 % lipids, a high lipid control group diet (HC) with 18 % lipids, and three high lipid diets supplemented with varying amounts of YPP at 4 g/kg (YP1), 8 g/kg (YP8), and 16 g/kg (YP16). After an 8-week feeding experiment, various indicators were measured to assess the effects of YPP. The growth performance results showed significant improvements in the weight gain rate (WGR) and specific growth rate (SGR) of the YP8 group compared to the HC group, Moreover, inclusion of 0.4 %YPP and 0.8 %YPP elevated the crude protein content in the body of largemouth bass. Observation of antioxidant indicators reveals that adding 0.4 %YPP and 0.8 %YPP to the diet can alleviate oxidative damage caused by a high-lipid diet in largemouth bass. YPP also improves liver and intestinal health. Additionally, incorporating 0.4 % YPP and 0.8 % YPP into the diet can lead to a significant reduction in triglyceride (TG) and total cholesterol (T-CHO) levels in both the liver and serum of largemouth bass. Similarly, adding 0.4 %YPP and 0.8 %YPP to a high-lipid diet resulted in the upregulation the expression levels of fatty acid metabolism genes such as peroxisome proliferator activated receptor alpha ( PPARα ) and carnitine palmitoyl transferase 1 ( CPT1 ). Conversely, it led to the downregulation the expression levels of genes involved in fatty acid synthesis and cholesterol synthesis such as fatty acid synthase ( FASN ), Sterol-regulatory element binding proteins ( SREBP-1 ) and 3-hydroxy-3-methylglutaryl-Coenzyme ( HMGCR ). In summary, YPP has a significant effect in improving oxidative stress and lipid metabolism disorders caused by high-lipid diets. Additionally, it can enhance the Protein-Sparing effect in fish, and promote their growth. • Adding YPP to a high-lipid diet enhances the Protein-Sparing effect of largemouth bass and improves its growth performance. • Adding YPP to the diet can alleviate the damage of high-lipid diet to the intestinal and liver morphology of largemouth bass. • Adding YPP to the diet can alleviate oxidative stress induced by a high-lipid diet. • Adding YPP to a high-lipid diet can enhance lipid metabolism in fish and reduce fat deposition in the liver.