EFFECTS OF DIETARY CARBOHYDRATE AND LIPID LEVELS ON GROWTH PERFORMANCE AND PLASMA METABOLITES IN JUVENILE BLUNT SNOUT BREAM

To test the effects of dietary carbohydrate and lipid levels on growth performance, body composition, nutrient retention and plasma metabolites in juvenile blunt snout bream (Megalobrama amblycephala) initial weight of (6.20±0.01) g, fish were fed with three isonitrogenous diets: HCLL (45% carbohydrate, 2% lipid), MCML (30% carbohydrate, 8% lipid), or LCHL (15% carbohydrate, 14% lipid) for 56 days. Results showed that dietary carbohydrate and lipid had no effect on FR, but declined dietary carbohydrate and increased lipid enhanced the SGR and FE. The HCLL diet did not induce the retention of glycogen and TG in the liver, nor did it alter morphological indices like HSI, VSI or CF. In addition, no significant differences were observed on the body composition of blunt snout bream fed with varying dietary carbohydrate and lipid levels, but as the dietary carbohydrate reduced and lipid increased the PRE elevated and LRE declined. Furthermore, no significant differences were found on the plasma glucose, TG, free fatty acids and cholesterol levels among all experiment group. The LCHL diet significantly induced the plasma LDL-C content, suggesting the liver transferred lipid to peripheral tissue to sustain the lipid homeostasis. In conclusion, the blunt snout bream can utilize lipid better than carbohydrate. Meanwhile, the blunt snout bream has an adaptive system that can cope with changes in dietary carbohydrate and lipid level. The present study can provide information for blunt snout bream feed formulation.