Effect of starch sources on growth, hepatic glucose metabolism and antioxidant capacity in juvenile largemouth bass, Micropterus salmoides

A 70 days experiment was carried out to investigate the effects of starch sources on growth performance, hepatic glucose metabolism and antioxidant capacity of largemouth bass, Micropterus salmoides. Fish (initial body weight: 16.8 ± 0.20 g) were fed four isonitrogenous and isolipidic semi-purified diets containing 10% wheat starch, cassava starch, pea starch and high-amylose maize starch, respectively. The results indicated that fish fed the peas tarch and high-amylose maize starch diets showed significantly better weight gain, specific growth rate and protein efficiency ratio compared with that fed the cassava starch diet. However, fish fed the wheat starch and cassava starch diets had a significantly higher hepatic glycogen and muscle glycogen contents than those fed the other diets. The alanine amiotransferase (ALT) and aspartate transaminase (AST) activities, glucose and insulin contents in plasma were lower in fish fed the pea starch and high-amylose maize starch diets than the other groups. There were significant differences in hepatic glucose metabolism enzymes in fish fed diets with different dietary starch sources. Both the highest glucokinase and pyruvate kinase activities in liver were observed in fish fed the cassava starch diet. However, the highest pyruvate carboxylase activity in liver was recorded in the high-amylose maize starch group. Moreover, the higher superoxide dismutase (SOD) and catalase (CAT) activities, the lower malondialdehyde (MDA) contents were observed in fish fed the pea starch and high-amylose maize starch diets. Results suggest that the starch types may affect growth performance and metabolic changes, whereas the pea starch and high-amylose maize starch were the most optimal carbohydrate sources for juvenile M. salmoides.