Optimization of protein requirements and feed restriction in Penaeus vannamei (Boone, 1931) biofloc culture

The production of Penaeus vannamei faces multiple challenges, from environmental constraints and disease outbreaks to the need for sustainable and improved farming practices, essential for responsible production. Biofloc technology offers a sustainable approach by enhancing water quality and serving as a complementary nutritional source. However, protein requirements in biofloc-based shrimp culture systems remain insufficiently defined despite their economic relevance. This study aimed to optimize dietary protein levels and feeding regimes for P. vannamei cultured under biofloc technology, while assessing the nutritional contribution of bioflocs through stable isotope analysis. A two-phase factorial experiment was conducted. In the juvenile stage, five diets containing 30–46% crude protein (CP) were tested under three feeding regimes (70, 85, and 100% of average daily ration). Shrimp fed 38% CP at 70% feeding achieved growth comparable to higher CP and feeding levels, indicating this combination as optimal for juveniles. In the grow-out phase, shrimp were fed 34–42% CP diets at a fixed 70% feeding rate. Growth was maintained even at 34% CP, suggesting lower protein requirements for larger shrimp. Growth performance, nutrient composition, and isotopic signatures (δ13C and δ15N) were evaluated to estimate carbon and nitrogen assimilation from feed and biofloc sources. Stable isotope analysis confirmed that biofloc contributed significantly to nitrogen and carbon assimilation, especially under reduced dietary protein. Results also demonstrate that a permanent 70% feeding strategy sustained shrimp performance under biofloc conditions. This outcome underscores the role of biofloc as a nutritional supplement, contributing to a more sustainable and cost-effective shrimp farming.