Effect of the Combined Supplementation of Nucleotides and Mannan Oligosaccharides as Feed Additives in the Diet of Penaeus vannamei in a Synbiotic System

The use of functional feeds in aquaculture has increased due to the reduction in fishmeal and the need to improve the gut health of farmed organisms. This study evaluated the effects of supplementing nucleotides (NT) and mannan oligosaccharide (MOS) in the diet of juvenile Penaeus vannamei reared in a synbiotic system for 60 days. Four treatments were tested: a control diet without additives (RC); a diet supplemented with 2 g NT kg−1 (NT); a diet supplemented with 2 g MOS (MOS); and a diet supplemented with 1 g NT kg−1 and 1 g MOS kg−1 (NT/MOS). Water quality, zootechnical performance, gut morphology, microbiota indicators, and economic benefits were evaluated. There were no significant differences in water quality or production performance among treatments. However, additive supplementation improved economic efficiency and net revenue, with the NT/MOS treatment showing a 7.06% economic gain relative to the control. MOS supplementation increased the proportion of Bacillus spp. to 13.9 × 107 CFU g−1, suggesting a prebiotic effect and potential control of Vibrio spp. Morphologically, supplemented shrimp exhibited shorter mucosal folds and thicker gut walls. NT and MOS supplementation appeared to be an economically promising strategy for shrimp production in synbiotic systems.