Effects of plant extract compound on growth performance, serum biochemical indices, liver and intestinal health of largemouth bass (Micropterus salmoides)

Largemouth bass has poor glucose metabolism. How to cope with liver sugar stress and inflammatory response of largemouth bass at high glucose level by nutritional means has become a research hotspot in recent years. This study was conducted to investigate the effects of dietary plant extracts compound, including mulberry leaf flavonoids, chestnut leaf tannin and mulberry leaf polysaccharide, on growth performance, serum biochemical indices, liver and intestinal health of largemouth bass. Three treatment groups with 4 replicates in each group were fed isonitrogenous and isolipid diets (J0, J1 and J2) supplemented with 0, 0.1% and 0.2% compound plant extract, respectively. The largemouth bass was fed for 56 days. The results showed as follows: compared with group J0, the final average weight, weight gain rate and specific growth rate of largemouth bass in group J2 were significantly increased by 8.34%, 11.24% and 5.88%, respectively (P<0.05); There were no significant differences in body ether extract, water content, ash content, calcium and total phosphorus in J0~J2 groups (P>0.05), The crude protein content in group J2 increased by 5.61% compared with group J0 (P<0.05); The hepatosomatic ratio of J1 and J2 group was significantly decreased by 9.10%-10.28%, the serum albumin content and albumin/globulin value were significantly increased by 8.28%-12.62% and 13.56%-23.73%, and the serum globulin content of J2 group was significantly decreased by 9.47%. Serum glutamic pyruvic transaminase and glutamic oxalacetic transaminase activities and blood glucose content in J1and J2 groups were significantly decreased by 31.25%-46.88%, 7.69%-12.54% and 20.90%-22.40%, respectively(P<0.05). The contents of cholesterol and triglyceride in the J1 and J2 groups were decreased, while the contents of high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were increased(P>0.05). The degree of hepatic lipid vacuolation was significantly decreased by 22.89%-36.22% in the J1and J2 groups, and the height of the intestinal villus was significantly decreased by 10.84%(P<0.05). In conclusion, the plant extract compound can significantly improve the growth performance and liver health of largemouth bass. The results provided a theoretical basis for evaluating the effects of plant extract compound in the diet of largemouth bass and provided a reference for the optimization of the diet formula of largemouth bass.