Use of different stocking densities of Litopenaeus vannamei juveniles using "synbiotics": effects on water quality, microorganisms, bioflocs composition and zootechnical performance.

In shrimp farming, the development of alternative production systems, such as fermented products, can help reduce the high dependence on artificial diets and ensure more sustainable growth. The "synbiotic system" typically uses low stocking densities in traditional earth ponds. To increase profitability, the tendency is to increase stocking densities, especially in small production units. The objective of the following work was to use the "synbiotic system" in different stocking densities, analyzing the water quality, the microorganisms present, the proximal composition of the formed bioflocs and the zootechnical performance. For this, 12 tanks with an area of 35 m2 each were used. Stocking densities were 30, 60, 90 and 120 shrimp/m2. Fertilization was carried out for seven days before the shrimp stocking and then every two days until the end of the experiment. The experiment lasted 45 days, and no water was renewed. Significant differences were observed in several quality parameters, including alkalinity, nitrate, total suspended solids, and turbidity. However, no significant differences were found in the proximal composition of the formed bioflocs. The presence of microorganisms throughout the experimental period indicated the effectiveness of adding fermented rice bran for nutrient assimilation. Furthermore, significant differences were observed in the final weight, feed conversion rate and productivity. The ability of the synbiotic system to provide food supplementation, control water quality and present satisfactory zootechnical performance was demonstrated, proving to be efficient in the cultivation of Litopenaeus vannamei. [ABSTRACT FROM AUTHOR]