Dietary carbohydrate-to-lipid ratios modulate juvenile hybrid grouper (♀ Epinephelus fuscoguttatus x ♂ E. lanceolatus): Effects on growth, serum biochemistry, intestinal digestion and hepatic metabolism of glucose and lipid

A 56 day feeding trial was conducted to study effects of different carbohydrate-to-lipid (CHO.L-1) ratios on growth, serum biochemistry, intestinal digestion and hepatic metabolism of glucose and lipid in juvenile hybrid grouper (Epinephelus fuscoguttatus x male E. lanceolatus). Results showed that moderate CHO.L-1 ratio resulted in better growth performance (p < .05). In serum, glucose, insulin and alanine aminotransferase were enhanced as CHO.L-1 ratios increased, whereas cholesterol was reduced (p < .05). Increased CHO.L-1 ratios resulted in raised activity of amylase and reduced activity of lipase in gut (p < .05). Gene expression related to glucose transporters improved (p < .05). Enzyme activity and gene expression involved in hepatic glycolysis improved in a limited manner, whereas enzyme activity and gene expression related to hepatic gluconeogenesis and lipolysis were inhibited in high CHO.L-1 ratio group. Enzyme activity of hepatic lipogenesis showed an elevated trend, including acetyl-CoA carboxylase and fatty acid synthase (p < .05). In conclusion, different dietary CHO.L-1 ratios affected growth, serum biochemistry, intestinal digestion and hepatic metabolism of glucose and lipid in grouper. Moreover, juvenile grouper could utilize diet containing moderate CHO.L-1 ratio.