Introduction
The production of Penaeus vannamei represents the main sector of global aquaculture; however, its intensification raises sustainability challenges, particularly related to fishmeal use and nitrogen waste management. Biofloc technology (BFT) has emerged as an alternative based on nutrient recycling into microbial biomass, improving water quality and providing a complementary nutritional source. However, its performance depends on multiple interrelated factors that have traditionally been studied in isolation. This study adopts an integrated approach, evaluating system optimization, nutritional efficiency, microbiota, and product quality to support more sustainable shrimp production.
Material & Methods
A series of experiments were conducted under super-intensive conditions in BFT systems. The following aspects were evaluated: (i) the effect of carbon sources (molasses, yeast, and polymers) and C:N ratios (10:1, 18:1, 26:1) on water quality, microbial dynamics, and growth; (ii) nutritional efficiency through different protein levels (30–46%) and feeding regimes (70–100%), including stable isotope analysis to estimate biofloc contribution; (iii) fishmeal replacement using isoproteic and isolipidic diets with alternative protein sources; (iv) characterization of biofloc and gut microbiota through 16S rRNA gene sequencing; and (v) preservative-free post-harvest quality, assessing slaughter methods and their effects on microbial load, spoilage, and sensory properties during refrigerated storage.
Results & Discussion
Results demonstrated that biofloc system performance is strongly influenced by carbon source and C:N ratio, affecting water quality, microbiota, and shrimp growth. Molasses, particularly at low to intermediate C:N ratios, emerged as the most suitable strategy, promoting a balanced and functional microbial community. This is likely due to greater carbon availability stimulating heterotrophic bacteria compared to slow-release sources such as polymers, despite better nitrogen control and higher diversity . In contrast, yeast treatment showed higher phosphate accumulation and a more dominated bacterial composition, limiting their productive advantage . These results indicate that heterotrophic activity is more relevant than diversity per se . Stable isotope analysis confirmed that biofloc contributes ~40% to shrimp nutrition allowing a 30% reduction in feeding rate without affecting growth and saving ���0.95/kg biomass, confirming overestimated requirement by conventional feeding tables . Dietary protein was optimized to 38% in juveniles and 34% in grow-out, consistent with reduced requirements as shrimp grow . Up to 92% FM replacement using alternative protein sources was feasible without compromising performance, confirming the compensatory role of biofloc and supporting reduced FM use . Diet also influenced product quality, with mixed diets providing the best balance between sensory attributes and reduced melanosis. Microbiota analysis revealed clear differentiation between biofloc and gut communities, mainly driven by system maturation and shrimp growth , rather than diet. Finally, slaughter methods affected preservative-free post-harvest quality, the most suitable method consist of a 5-minute immersion in chilled seawater with 50 ppm sodium hypochlorite followed by thermal shock in ice slurry. Overall, these results demonstrate that BFT can be optimized through an integrated approach that improves efficiency, reduces feeding costs, enhances sustainability, and improves product quality.
Acknowledgment
This abstract is part of the "BioFlango" project (PID2020-114574RB-C21) and "ZeroFloc" project (PID2023-149570OB-I00), funded by MICIU/AEI/10.13039/501100011033 and by the European Union and NextGenerationEU/PRTR respectively. S. Ferrando-Juan is the recipient of a predoctoral grant (PRE2021-098367) funded by MICIU/AEI/10.13039/501100011033.
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