Metabolic adaptation to high starch diet in largemouth bass ( Micropterus salmoides ) was associated with the restoration of metabolic functions via inflammation, bile acid synthesis and energy metabolism.

A short-term 2-week (2w) and long-term 8-week (8w) feeding trial was conducted to investigate the effects of low and high starch diets on the growth performance, metabolism and liver health of largemouth bass (Micropterus salmoides). Two isonitrogenous and isolipidic diets containing two levels of starch (LS, 9.06%; HS, 13.56%) were fed to largemouth bass. The results indicated that HS diet had no significant effects on SGR during 2w, whereas significantly lowered SGR at 8w. HS diet significantly increased hepatic glycolysis and gluconeogenesis at postprandial 24h in 2w. The HSI, plasma AKP, TBA levels, and hepatic glycogen, TG, TC, TBA, NEFA contents were significantly increased in the HS group at 2w. Moreover, HS diet up-regulated fatty acid and TG synthesis-related genes, and down-regulated of TG hydrolysis and β oxidation-related genes. Therefore, the glucolipid metabolism disorders resulted in metabolic liver disease induced by HS diet at 2w. However, the up-regulation of bile acid synthesis, inflammation and energy metabolism-related genes in 2w indicated that largemouth bass was still in a state of "self-repair" response. Interestingly, all the metabolic parameters were returned to homeostasis, with up-regulation of intestinal glucose uptake and transport-related genes, even hepatic histopathological analysis showed no obvious abnormality in the HS group in 8w. In conclusion, HS feed induced short-term acute metabolic disorder, but long-term metabolic adaptation to HS diet was related to repairing metabolism disorders via improving inflammatory responses, bile acid synthesis, and energy metabolism. These results strongly indicated that the largemouth bass owned certain adaptability to high starch diet.