Immunostimulation of Pacific white shrimp (Penaeus vannamei) through dietary NagroWall enhances resistance to Vibrio parahaemolyticus infection.

In intensive shrimp aquaculture, the primary challenge is enhancing shrimp innate immunity to increase resilience against Vibrio-caused diseases. NagroWall, a commercial product containing prebiotic compounds (mannan-oligosaccharides, β-glucans, nucleotides, and nucleosides) has been proposed as an alternative to antibiotics. This study evaluated the effect of adding NagroWall to Penaeus vannamei diet on growth and immune responses against Vibrio parahaemolyticus infection. 9600 juvenile shrimp (5.06 ± 0.10 g) were divided into four treatment groups in quadruplicates. Four treatment diets were formulated by adding 0, 1, 2, and 3 g 100 g-1 NagroWall to the basal diet (NW0, NW1, NW2, and NW3), and the feeding experiment spanned 60 days, with the respective diets administered three times daily at 06:00, 12:00, and 18:00H. The final weight, weight gain, and specific growth rate of shrimp fed NW2 were significantly higher than those of the other groups (P < 0.005). A better feed conversion ratio, increased digestive enzyme activities, and muscle protein retention were observed in shrimp fed the NW2 diet (P<0.005). The survival rate and muscle amino acid composition were not significantly different between the treatment groups (P ˃ 0.005). After 7 days challenge test, shrimp fed NW2 showed higher antioxidant enzyme activities than the other treatments. Non-specific immune parameters and relative mRNA expression of immune-related genes (LYZ, TLR, and IMD) were significantly higher in shrimp fed NW2 diets (P < 0.005). A reduced mortality rate following Vibrio infection was observed in NW2 compared to the other groups. In conclusion, supplementation with 2 g 100 g-1 NagroWall enhanced the growth performance and resistance of P. vannamei to V. parahaemolyticus by modifying the innate immunity.