Dieta funcional para juvenis de beijupirá: inclusão da alga marinha Ulva fasciata

Abstract

One of the major obstacles to the production of cobia (Rachycentron canadum) is the formulation of diets that meet the nutritional needs of the species in captivity. In view of this, the use of functional foods in animal diet has been valued due to the health benefits that these foods can promote. The Ulva fasciata macroalga has biological activities, such as antioxidant and antiflammatory action. Therefore, this study aimed to include Ulva fasciata meal as a functional ingredient in the diet for this species. Thus, contributing to the development of sustainable techniques of beijupirá production, a multi-trophic aquaculture unit integrated in a water recirculation system was set up, with U. fasciata being one of the filtration stages. For the evaluation of the efficiency of the use of macroalga in the diet of the fish, isoproteic, isoproteic and isocaloric pelleted diets with inclusion of Ulva fasciata meal (0.00; 5.00, 10.00 and 15.00%) with three replicates per treatment. Twenty fish were distributed in each experimental unit of 310 L. To evaluate the performance at 62 and 94 days of experiment, cobia juveniles were fasted for 24 hours. The parameters evaluated were: food intake, final weight, weight gain, feed conversion, length, food efficiency index, food consumption index, specific growth rate, protein efficiency ratio and condition factor. Responses to the increasing values of Ulva fasciata meal were evaluated by regression analysis for performance parameters, and analyzed using the quadratic regression models, according to the best fit obtained for each variable. The results were submitted to the analysis of variance by means of the test of means (Tukey) at 5% probability of error, for the following parameters: body weight, viscera weight, liver weight, viscerosomal index (VSI), hepatosomatic index (HIS), body composition of eviscerated fish, catalase activities, glutathione S-transferase and morphometric measurements of the small intestine. The statistical program used was SISVAR. For the two evaluated periods, there was no significant difference for feed intake. In the other parameters evaluated there was a significant difference at 62 and 94 days of experimentation, and for all parameters the best inclusion percentage of the macroalga was 10%. There were differences for fish weight at 94 days and viscera weight. There was no difference for liver weight, VSI and HSI. There was a significant effect for mitochondrial and cytoplasmic catalase activity of the liver at 94. There were significant differences for body composition of eviscerated gossy juveniles. The moisture, ashes and protein of the body composition did not differ between the treatments. The percentage of lipids of the fish that did not receive the U. fasciata meal was significantly lower than the fish that received 10 and 15%. There was no difference for intestinal morphometry. The U. fasciata macroalga can be included in diets for cobia juvenile