Dietas extrusadas e peletizadas com baixo e alto nível de lipideos na alimentação de pacu (Piaractus mesopotamicus)

Abstract

The objective of this work was to evaluate the effect of diet processing (pelleting or extrusion) with high and low levels of lipids on the development, digestion transit time, nutrient retention efficiency and histomorphological adaptations of Piaractus mesopotamicus. Gastrointestinal transit time, growth and nutrient retention efficiency in pacu subjected to four isoprotein diets (22.1 ± 0.7 % digestible protein, DP) containing two levels of lipids (4% or 8%), and submitted to pelletisation or extrusion processes, were used. They were analyzed according to a factorial experiment (2 x 2), with two levels of lipids (4 and 8%) and two types of diet processing (pelletization and extrusion), in an entirely randomized design (DIC) and three repetitions. The data were analyzed according to the parametric ANOVA test, followed by Tukey post-test, assuming P<0.05 as significance level. Diet characteristics, growth rates, nutrient and energy retention efficiency, gastrointestinal transit time and foregut histology were analysed. Dietary processing was influenced by lipid levels. Growth, nutrient retention efficiency and digestibility revealed that the protein-sparing effect of lipid was observed in the extruded diets. The increase in lipid, as well as the processing applied to the diets, evidenced adaptations in the morphology of the digestive tract of pacu that resulted in improved absorption of available nutrients. It is concluded that extruded diets with 8% lipid promote better growth rates, high efficiency of lipid retention without gastric disturbances.