Nutritional and metabolic responses in common dentex (Dentex dentex) fed on different types and levels of carbohydrates

Abstract

The present studywas aimed to evaluate the capacity of common dentex (Dentex dentex) toefficiently use dietary carbohydrates. So, the effects of different type and levels of carbohydrates on growth performance, feed utilization, fish composition, plasmametabolites and keymetabolic pathways in liver andwhite muscle of common dentex are presented. Nine isonitrogenous (43%) and isoenergetic (22MJ kg−1) diets were formulated combining three types, pregelatinized starch (PS), dextrin (Dx) andmaltodextrin (Mx), and three levels (12, 18 and 24%) of carbohydrates. Growth performancewas not significantly influenced by treatments. The best feed utilizationwas observed in 18% Mx group. Higher hepatic lipid content was found in fish fed lower dietary carbohydrate levels. PS induced higher liver and white muscle hexokinase and pyruvate kinase activities compared to the lower values observed for Mx. Malic enzyme and glucose 6-phosphate dehydrogenase in liver and white muscle were lower in Mx group. The influence of dietary carbohydrates source was more noticeable than those induced by the carbohydrate level, when glycolysis and lipogenesis pathways were considered. Common dentex is able to use properly dietary carbohydrates, although optimal dietary inclusion levels are below 24%. The greater protein-sparing effect was promoted by the less complex carbohydrate (maltodextrin) and the best feed utilization indices were obtained at intermediate levels of inclusion (18%).