Effects of short feed restriction cycles in Piaractus brachypomus juveniles

Abstract

This work aimed to evaluate the effects of short feed restriction cycles on Piaractus brachypomus juveniles during the initial growth phase. A total of 750 fish (average initial weight of 2.4 g and density of 1 fish per 2 l of water) were distributed in 15 rectangular tanks maintained in a recirculation aquaculture system for 35 days. Fish were divided into three treatments: Control, fish continuously fed; 6F/1R, fish fed for six days and subjected to feed restriction for one day (on Sundays); and 5F/2R, fish fed for five days and subjected to feed restriction for two days (on Saturdays and Sundays). Fish were fed until apparent satiation two times a day (09 h00 and 16 h00) using an extruded commercial diet (2.6 mm diameter and 36% crude protein). There were no significant differences in survival among treatments (P > 0.05). Treatment 5F/2R had lower final weight, length, weight gain and specific growth rate compared to the control (P < 0.05), while these variables did not differ significantly from the control for the 6F/1R treatment. Food intake for both treatments submitted to feed restriction (6F/1R and 5F/2R) was lower compared to control. Feed conversion rate and protein efficiency ratio did not differ significantly among treatments (P > 0.05), nor did hematocrit and hemoglobin concentration (P > 0.05). Treatment 5F/2R had lower triglycerides than the control, while the other parameters (glucose and cholesterol) did not differ. Liver lipids, muscle lipids and the mesenteric fat index did not differ significantly among treatments (P > 0.05), however, the hepatosomatic index for 5F/2R was significantly lower than the control (P < 0.05). The adoption of short cycles of one day of feed restriction per week (treatment 6F/1R) appears to be a very satisfactory strategy in the production of juvenile P. brachypomus with an initial average weight of 2.4 g, as these animals showed good growth performance responses and did not experience changes in their hematological, biochemical and tissue parameters.