Growth and body composition of juvenile curimata pacu (Prochilodus argenteus) fed diets with different protein: lipid ratios

Abstract

Promising species for aquaculture need to have their nutritional requirements defined. Considering that protein is the most expensive macronutrient in aquaculture diets, the present study aimed to estimate the protein requirement of curimata-pacu fed with diets containing two lipid levels. Thus, eight experimental diets were formulated to contain 20, 25, 30 and 35% of crude protein (CP) associated to 11 and 15% of crude lipids (CL) were formulated, constituting a completely randomized factorial design (4 CP x 2 CL) with three replicates per treatment. The juveniles (3.6 ± 0.01 g) were fed daily with 6% of the biomass, three times a day (08:00, 12:00 and 16:00 h) for 70 days. The protein requirement was estimated by the combination of the broken line and quadratic regression models. The CP concentration in the diets was the only factor influencing ( P 0.05) with the CL level of the diets. The requirement for weight gain and fish feed efficiency was estimated at 32.5 and 34.5% CP. Protein retention decreased ( P < 0.05) in proportion to CP elevation. Fish fed 15% CL had higher ( P < 0.05) body lipid deposition. On the other hand, the increase of CP of the diets decreased ( P < 0.05) lipid deposition in juveniles. Therefore, it is recommended that young curimata-pacu between 3 and 27 g in weight should be fed diets containing 32.5-34.5% CP and 11% of CL, equivalent to a protein: energy ratio of 22-23 mg kJ -1 .