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Carbohydrates utilization by pacu: structural characteristics of starch


Proper inclusion of carbohydrate in fish diets for maximum utilization of dietary protein for growth is an interesting tool to reduce costs of production and nitrogen excretion. In fish relative use of carbohydrates in the diet is related to metabolism and peripheral utilization of this nutrient. This study will evaluate the effect of different amounts of amylose and amylopectin in diets for juvenile pacu (Piaractus mesopotamicus) and its influence on carbohydrate metabolism and growth performance of fish. Two experiments will be conducted. Both will be conducted in a completely randomized design with six treatments and four replicates. Six experimental diets with vitamin and mineral premixture, 23% crude protein (21% PD estimated), EB 4000 kcal/kg of diet and 34% starch will be formulated. Different amounts of amylose / amylopectin will be provided by the inclusion of different amounts of regular corn starch (27.8% amylose, 72.2% amylopectin), waxy maize (1.8% amylose, amylopectin 98.2%) and high amylose corn starch (71% amylose and 29% amylopectin). In the first experiment will be study the effects of experimental diets on apparent digestibility, amylase activity in the intestine and intestinal microbiota. In the second, after 90 days of feeding, will be evaluated growth performance, body composition and nutrient retention, blood metabolites and tissue energy reserves and hepatic activity of key enzymes of metabolic pathways. The results will be submitted to ANOVA and means will be compared by Tukey test (5%). (AU)