Levels of dietary carbohydrate on enzyme activity to pacu Piaractus mesopotamicus (Holmberg, 1887)

• Grant number: 14/14530-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2014
• End date: August 31, 2015
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Thiago Archangelo Freato
• Grantee: Lucas Cuchi Ribeiro
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Considering the economic importance of the pacu Piaractus mesopotamicus in Brazilian aquaculture, studies about the nutritional requirements of this omnivorous species, are still incomplete. This project aims to determine the influence of dietary carbohydrate levels on enzyme activity of pacu and complements a ample project, which aims to determine the optimal point, nutritional and economically feasible, of dietary carbohydrate and lipid for the commercial production of the species, well as its influence on digestive physiology, metabolism, muscle growth dynamics and nutrient deposition in the carcass of the species. In this study will be carried a dose-response assay, where a increasing levels of dietary carbohydrate (18, 20, 22, 24, 26, 28, 30 and 32% of non-nitrogenous extractives - ENN) will be provided to juveniles pacu. These levels were determined according to the results of a previous experiment conducted under the same experimental conditions, in which the level of 25% of ENN in the diet resulted in higher rates of growth performance in relation to levels of 30, 35, 40 and 45% of ENN, with a linear effect to weight gain and feed conversion. The fish will be distributed in thirty-two aquariums in a recirculation system water with strict control of temperature and forced aeration. After 90 days feeding the experimental diets, will be determined the activities of lipase and amylase in the stomach, intestine and pyloric cecum of pacu. The tests will be conducted in a completely randomized design with 8 treatments (n = 4) and the data subjected to analysis of variance and mean comparison tests. Regression analyzes will also be used to study the enzymatic activity depending on the levels of carbohydrates in the diet. At the end of the study, is expected to determine the possible variations in the intensity of enzymatic activity as well as their distribution along the digestive tract of pacu and discussing the possible influences on carbohydrate utilization by species. (AU)