Effect of commercial probiotics addition in a biofloc shrimp farm during the nursery phase in zero water exchange

In biofloc technology systems (BFT) the bacterial community plays the most important role at recycling the organic matter and metabolizing the toxic nitrogenous compounds. The aim of this study was to evaluate the effect of two groups of commercial probiotics on the abundance of viable heterotrophic bacteria (VHB), ammonia oxidizing bacteria (AOB) and Vibrio-like (VLB), nitrogenous compounds and productive parameters of whiteleg shrimp Litopenaeus vannamei in a commercial farm. The study was developed during nursery phase in zero water exchange. Two groups of probiotics (PB1 and PB2) and one control (PBN; no probiotic) were evaluated in three replics. Shrimp postlarvae (7.3 mg) were stocked in ponds (70 m3) at densities of 500 in./m2. Commercial probiotics (Efinol PT-Lab. Robles and Epicin ponds-Epicin hatcheries) were incubated for 36 h in bioreactors (1 m3) and supplied every 3 d in PB1 and PB2 treatments. Basic variables of water quality, nitrogenous compounds and bacterial groups were monitored. At the beginning of the experiment, the abundance of VHB was lower in the PBN treatment, but as the bioassay progressed, the densities were similar to PB1 and PB2. In general VLB showed similar tendency to VHB, but significant difference were determined among treatments. The AOB abundance was similar in all treatments. Nitrogenous compounds and productive parameters of shrimp did not show significant differences between treatments. In the PBN ponds the zero water exchange could have promoted benefical bacteria of the natural biota. The addition of probiotics did not improve the water quality nor productive response of L. vannamei.