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Different strategies have been adopted aiming to improve either performance, water quality and health on intensive shrimp farming, including the manipulation of the bacterial community in biofloc technology (BFT) systems. The experimental design was completely randomized, with three treatments in triplicate developed in BFT without water exchange; CONT (control, only BFT without external addition of bacteria); NIT (addition of nitrifying bacteria in BFT water); LACT (BFT with addition of Lactobacillus rahamnosus in the pelletized feed). The experiment was carried out under controlled conditions, with juveniles of white shrimp Litopenaeus vannamei (0.56 g / ind as initial weight). During the bioassay (35 days), the basic variables of water and nitrogenous compounds (TAN, NO2-N and NO3-N) were monitored. At the end of the experiment, the abundance of ammonium oxidizing bacteria AOB), heterotrophic bacteria and Vibrio-like bacteria, the proximal composition of the biofloc and the shrimp tissue were analyzed. There were significant differences in the levels of DO, pH, TSS and alkalinity. In the NIT treatment, the minimum amount of TAN and NO2-N was recorded, and the nitrification curves occurred in less time. In terms of bacteria profile, the highest abundance of heterotrophic bacteria in water was recorded in the LACT treatment (36.8 × 106 CFU / mL) and the highest amount of OAB and Vibrio-like bacteria (yellow colonies) occurred in the NIT treatment (7.5 × 106 and 10.6 × 103 CFU / mL, respectively). The proximal composition of biofloc was different, the protein varied from 20.04 to 25.59%, the highest corresponded to CONT. Similarly, the proximal composition of shrimp was different, the protein varied from 69.61 to 71.42%, the maximum was recorded in LACT. The best productive parameters were registered in the LACT and NIT treatments, (specific growth 5.31, 5.18% / day; survival 99.6, 99.0% and FCR: 0.94, 1.00, respectively). In our experimental conditions, the addition of external bacteria (nitrifying and Lactobacillus rhamnosus) had a significant positive impact on the quality of the water, proximal composition and productive parameters of the shrimp, as well as on the abundance of bacteria. |
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