Effect of dietary carbohydrate sources on the growth, glucose metabolism and insulin pathway for swimming crab, Portunus trituberculatus

An eight-week feeding trial was conducted to investigate the effects of dietary carbohydrate sources on growth performance, glycogen content in tissue, insulin signaling pathway, hepatic glucose transport and metabolism in juvenile swimming crab (Portunus trituberculatus). Four isonitrogenous (approximately 45.4% crude protein) and isolipidic (approximately 9.0% crude lipid) experimental diets were formulated to contain corn starch, wheat starch, dextrin and potato starch. Each diet was randomly assigned to triplicate groups of 30 juvenile swimming crabs (approximately 5.6 ± 0.1 g) that were stocked in rectangle plastic baskets. The results indicated that crabs fed with corn starch, wheat starch and dextrin diets had significantly higher final body weight (FBW), weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) than those fed with potato starch diet. However, crabs fed with potato starch diet had the highest feed intake (FI) among all treatments. Crabs fed with corn starch, wheat starch and dextrin diets exhibited significantly higher glycogen in tissue and ATP content in hepatopancreatic than those fed with potato starch diet. The lowest concentration of insulin-like and hyperglycemic hormone were observed in crabs fed with potato starch diet. The lowest relative expression levels of PK, FBpase, PEPCK, GLUT1, GLUT2, GK, G6PDH, 6PGDH, ACC, IGF1R, PI3K and FOXO were occurred at crabs fed with dextrin diet. In conclusion, swimming crab could make better use of corn starch, wheat starch and dextrin, however, potato starch is not suitable as carbohydrate source. The results demonstrated that the ratio of amylose/amylopectin in diets was positively correlated with expression levels of genes related to glycolipid metabolism, glucose transport and insulin pathway.