Crescimento de alevinos de Oreochromis niloticus em sistema de bioflocos e submetidos a diferentes níveis protéicos

Abstract

Among the several ways of intensive production in aquaculture that have been highlighted through good results with limited water use and allowing higher densities in culture is the biofloc technology (BFT). This work evaluates the performance of the intensive cultivation of Nile tilapia - Oreochromis niloticus - with bioflocosis technology in the raising phase, with a mean weight of 2.9 ± 0.09 g, using different levels of crude protein (CP) (commercial). The experimental design was completely randomized, involving four levels of protein (28, 32, 36 and 45% of CP), with four replicates each. The work lasted 63 days, and was carried out in boxes of 40L of useful volume, with 10 fish in each box (250 alevinos / m³). We evaluated, Weight Gain, Daily Weight Gain, Specific Growth Rate, Survival, Biomass Gain, Food Conversion Factor and Productivity. Among the water quality variables, the temperature and pH were within the comfort range of the species (27 and 32 ° C, 6 and 8.5) respectively, the dissolved oxygen had averages above 6mg / L. Nitrogen from total ammonia as well as nitrite was within the acceptable level for the cultivation of the species (18.6 mgL -1 and 2.12 N-NO2). The performance variables were not affected by the different levels of dietary protein (P> 0.05). The final weight was about 35g for the treatments and survival was higher than 75% for all treatments, while the productivity ranged from 6.62 to 10.08kg / m³. The study showed that crude protein levels of the feed can be reduced up to the level of 28% of crude protein in the diet in the intensive cultivation of Nile tilapia fingerlings - Oreochromis niloticus - using the biofloc system, without compromising the weight final weight gain, daily weight gain, specific growth rate, food talk factor, survival and productivity.