Efeito de diferentes níveis de proteína na alimentação de Macrobrachium rosenbergii cultivado em sistemas intensivos de produção

Abstract

With the increase in population and the need to supply it with high quality animal protein there is a need for greater efficiency in aquaculture activities, aiming at better use of water and lower effluent emissions, associated with higher productivity and profitability. The concern with sustainability is one of the biggest challenges on the innovation agenda in aquaculture. Cultivation systems dependent on the constant renewal of water that produce toxic effluents are no longer in line with the global water crisis and require alternative production systems. Thus, the present research aimed to evaluate the zootechnical performance of Macrobrachium rosenbergii farmed in heterotrophic and autotrophic systems, fed with different crude protein contents in the nursery (35 and 40%) and grow-out (30 and 35%) phases. The nursery phase lasted 21 days, in which the combinations were tested: AUT 35, AUT 40, HET 35 and HET 40, with four repetitions. The data were submitted to the Shapiro-Wilk normality and Levene homogeneity tests, and then the water quality results were submitted to repeated measures analysis of variance; the zootechnical performance, basic costs, and microbiological analysis results were submitted to two-way analysis of variance; and when significant differences were observed, the data were submitted to the Tukey test. To evaluate the non-parametric data, the Mann-Whitney (U), Kruskal-Wallis, and Friedman tests were performed. The data were analyzed adopting the 5% significance level, using the Statistica 12.5 program. The zootechnical performance of the shrimp and the centesimal composition of the feed used and biofloc, the culture water quality and the basic production costs were determined. The fattening experiment lasted 42 days, consisting of the combinations: RAS 30, RAS 35, HET 30 and HET 35, with three repetitions. For this purpose, the zootechnical performance of the farmed animals, water quality and microbiological analysis of the animal tissue and farm water were determined. No significant differences were found for temperature, dissolved oxygen and pH, as well as for zootechnical performance indices in the nursery phase; and for temperature, dissolved oxygen, pH, alkalinity, total ammonia nitrogen and nitrite nitrogen and settleable solids, final weight, weight gain, specific growth rate, feed conversion factor and survival in the fattening phase. Significant differences were detected among the different culture systems for: NAT, N-NO2, N-NO3, total alkalinity, total hardness and PO43- during nursery; and for N-NO3, PO43-, total hardness during fattening, as well as for productivity, biomass gain and final biomass, with the autotrophic system showing the highest results. It was concluded that it is possible to reduce the protein content of the feed, in both phases of culture, without