Metabolic fitness and growth performance in tropical freshwater fish Labeo rohita are modulated in response to dietary starch type (gelatinized versus non‐gelatinized) and water temperature

This study investigated the modulating effect of temperature variation on the metabolic status and growth performance of tropical freshwater fish, Labeo rohita, when reared with starch‐based gelatinized (G) or non‐gelatinized (NG) diet. Fish were either maintained at ambient water temperature (26 °C) or exposed to 32 °C for 1 week, and then subjected to 26 °C for 4 weeks. Both groups were fed with isoproteinous (300 g kg^?1) diets containing G or NG starch. A significant interaction was evident between increased metabolic activity due to the short‐term exposure to higher temperature and starch type on growth performance, feed efficiency and protein retention. Dietary starch type and water temperature interactions were more effective in modulating the hepatic glucokinase and pyruvate kinase responses than that of hexokinase. Hepatic aspartate amino transferase and alanine amino transferase activities were augmented at low temperature in NG starch fed group. Overall, our findings indicate that enzyme activities are enhanced due to the short‐term exposure to higher temperature (32 °C). This elevated temperature lasted for 3 weeks after exposure during which NG starch tended to support the growth.