Effect of high-carbohydrate diet on growth performance, feed utilization, glucose and lipid metabolism of GIFT Oreochromis niloticus

To investigate the effects of high-carbohydrate diet on the growth performance, feed utilization, glucose and lipid metabolism of GIFT Oreochromis niloticus, we had fed the GIFT juveniles initial body mass (20.34±0.42) g with normal diet (C diet, 34% cholesterol level, dietary energy of 13.68 kJ · g^-1), high-carbohydrate and high-energy diet (HCE diet, 48% cholesterol level, dietary energy of 16.03 kJ · g^-1) and high-carbohydrate isoenergy diet (HE diet, dietary energy of 13.81 kJ · g^-1) in indoor circulating water system for 60 d.The results show that the weight gain rate, specific growth rate, liver crude protein contents of HCE and HE groups were lower than those of C group significantly (P < 0.05);while HCE and HE groups had significantly higher feed conversion ratio, crude fat content and glycogen content of liver, apparent digestibility of carbohydrate, low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C).The weight gain rate, whole body fat content, serum triglyceride (TG), total cholesterol (T-CHO) of HE group were lower than those of HCE group significantly (P < 0.05).The activities of glucokinase (GK) of HCE and HE group were higher than those of C group, and glucose-6-phosphate dehydrogenase (G-6-PDH), malic enzyme (ME), fatty acid synthase (FAS) of HCE were the highest in the three groups, and those of the C group were the lowest (P < 0.05).High carbohydrate groups induced swelling of liver cells and appearance of vacuoles.Hepatic injury was more serious in HCE group.In conclusion, GIFT can tolerate the feed with 48% carbohydrate content, but that is not conducive to the growth and health of GIFT, leading to fat accumulation and liver injury, disorder of glucose and lipid metabolism especially fat metabolism.