Dietary non-protein energy sources regulate growth and digestion of barramundi juvenile (lates calcarifer)

This study evaluated the effects of different dietary non-protein energy sources on growth performance, somatic parameters, histology and digestive enzymatic activity of barramundi (Lates calcarifer). Fish were fed ioso energy diets (18 kJ/g) with two types of non-protein energy sources in the experimental groups and a regular diet was used as the control. The feeding trial lasted for 56 days. Results from the present study indicate that, except for weight gain and feed intake, most growth parameters of fish were not significantly affected by the experimental diets (P > 0.05). Lipid group had higher whole body and muscle lipid, hepatosomatic index (HSI) and intraperitoneal fat ratio (IPF). The number of goblet cells and the height of the mucosa in the HL were significantly higher than those in the other two groups. The lipase activity of HL and HC was higher than that of control group in both stomach and foregut. This study indicates that increasing the proportion of lipid in the dietary improves growth performance and digestion performance of barramundi, while higher proportions of carbohydrate in the diet don't affect their growth performance. Considering the cost of production, carbohydrate could be a potential energy supplementing source.