2.4. Diets and body composition analyses and biochemical assays
Moisture of diets and whole fish was measured after dry at 105 ?C with 24 h. The total protein content of diets and whole fish were measured by a semi-automatic Kjeldahl System (FOSS, Sweden) after sulfuric acid digestion. The total lipid of diets and whole fish were extracted using chloroform/methanol (2:1, v/v) (Lambert and Dehnel, 1974). The activities of lactate dehydrogenase (LDH), glutamic propylic transaminase (GPT), glutamic oxaolacetic transaminase (GOT), lipase, amylase, and the contents of glycogen, lactate, hemoglobin, triglyceride (TG), total cholesterol, total amino acid (TAA) and the protein (BCA method) in tissues were determined using commercial kits (Nanjing Jiancheng Bioengineering Institude, China). Protease activity of gut was determined using fish Protease enzyme-linked immune sorbent assay (ELISA) kit (Shanghai Hengyuan Biological Technology Co., LTD, China). All measurement steps refer to relevant kit protocol and the results were recorded on a microplate reader (Epoch, BioTek, USA). Glucose content of blood was detected by using a blood glucose monitor (Glucose dehydrogenase method, CONTOUR?PLUS Blood Glucose Monitoring Systems, Bayer).
