Use of probiotic in the super-intensive cultivation of white shrimp (Litopenaeus vannamei) in a system without water renewal
The present study aimed to evaluate the effect of the probiotic both on water quality and on the growth and feed conversion of Litopenaeus vannamei grown in a super-intensive system without water renewal in the presence of microbial flakes. Therefore, during 30 experimental days, juveniles of L. vannamei with initial average weight of 0.047 ± 0.024g were grown in 8 rectangular concrete tanks painted with epoxy paint (1.43 m2, 750 L) in a density of 300 shrimp / m2 in 2 treatments with 4 replicates. In the Probiotic treatment (P) an initial dose of 2 ppm was applied followed by daily doses of 0.5 ppm of probiotic (a commercial product composed of 5.0 x 105ufc / g of Bacillus subtilis and Bacillus licheiniformis; ProW INVE®). In the control treatment tanks (C) the prawns were grown without the addition of a probiotic.For the development of the microbial flake, all tanks were fertilized with an initial application of molasses and wheat bran as carbon sources to encourage the growth of heterotrophic bacteria. In addition, during the experimental period, the concentration of total ammoniacal nitrogen (TAN) was monitored to calculate the amount of molasses to be added, assuming that 6 g of carbon are necessary to convert 1 g of TAN into bacterial biomass. At the end of the experiment, the suspended material (microbial flake) was collected for analysis of chemical composition. There was no significant difference between the water quality parameters monitored in both treatments during the experimental period. Survival and feed conversion did not show significant differences between treatments.Likewise, survival and feed conversion factor did not show significant differences between treatments. However, the prawns grown in the Probiotic treatment showed significantly higher final average weight (p <0.05) (0.78 ± 0.32 g) compared to the control (0.66 ± 0.21 g). The chemical composition of the microbial flake in the treatment with probiotic showed protein and ether extract significantly higher than the control, which may have provided the best performance of the shrimp. Therefore, the use of probiotics in a heterotrophic medium can be recommended as an alternative to improve the nutritional quality of the microbial flake and the performance of the shrimp.