Níveis de proteína bruta e lipídios em dietas para juvenis de tambatinga (Colossoma macropomum x Piaractus brachypomus)

Abstract

Protein is a high-cost nutrient essential for fish growth and its use as an energy source is undesirable. In this study, crude protein levels (200, 250, 300 and 350 g kg-1) and lipids (110 and 140 g kg-1) were evaluated in diets for tambatinga juveniles (Colossoma macropomum x Piaractus brachypomum) during 63 days. A total of 264 juveniles (15.2 ± 0.2 g) were distributed in aquariums of 160 liters (11 fish/aquarium), in a completely randomized 4x2 factorial design (n = 3). Diets were given three times daily until apparent satiety. The survival rate was 100% at the end of the experiment. The weight gain and the specific growth rate were influenced (p< 0.05) by crude protein and crude lipid and through the interaction between both. Feed intake was influenced by the lipid (p< 0.05) and protein (p< 0.05) concentrations in their feed, although the interaction between them was not significant (p> 0.05). The maximum feed efficiency was observed with 308 g kg-1 crude protein. Protein retention was inversely proportional (P< 0.05) to the dietary protein increment in diets with lower lipid concentration (110 g kg-1). The increase in dietary lipids decreased the demand for CP for maximum protein retention, estimated at 292.7 g kg-1 CP. Lipid concentrations affected (p<0.05) the concentration of moisture, protein, and body lipids. The minimum requirement for the mean final weight of juvenile tambatinga is 253 g kg-1 in diets with 140 g kg-1 of lipids and an energy: protein ratio of 13.8 g kcal ED g-1 CP.