Dietary supplementation with fermented prebiotics and probiotics can increase growth, immunity, and histological alterations in Pacific whiteleg shrimp (Litopenaeus vannamei) challenged with Vibrio parahaemolyticus

This study aimed to assess the water culture supplementation of fermented prebiotic (mannanoligosaccharide, MOS) and probiotic (Bacillus subtilis WB60) on water quality parameters, growth performance, feed utilization, immunity response, intestinal microbes, and histological investigations of Pacific whiteleg shrimp (Litopenaeus vannamei) challenged with Vibrio parahaemolyticus. Shrimp juveniles (4.98 +/- 0.11 g) were distributed into four experimental groups (twelve 1 m3 hapa, 25 shrimps/m3/each hapa, 3 triplicates/group). The first group (G0) used only fermented B. subtilis at a rate of 0.2 g/acre. The 2nd, 3rd, and 4th groups contained the same constant level of B. subtilis (0.2 g/acre) with three different levels of fermented MOS at 25, 50, and 75 g/acre (G1, G2, and G3, respectively). The results showed that TAN and NH3 values were significantly lower in all fermented groups compared to G0. Increasing the levels of fermented MOS led to significant improvements in growth performance, feed utilization, shrimp biomass, survival rate, crude protein, and ash content (p < 0.05). Compared to G0, the values of SOD, CAT, and IgM were significantly improved, while MDA levels were significantly decreased in all fermented MOS levels (p < 0.05). The G3 group exhibited the highest values of immune responses, including total hemocyte count, phagocytic activity, phagocytic index, respiratory burst activity, and lysozyme activity, as well as phenol oxide activity and total aerobic bacteria compared to the other groups (p < 0.05). Moreover, the G2 and G3 groups showed significantly lower mortality (30%) of shrimp challenged with V. parahaemolyticus infection compared to G0. In conclusion, the commercial scale recommends using fermented MOS and B. subtilis (50-75 g/acre) as water culture additives for shrimp L. vannamei due to the improvements in growth performance, feed utilization, immunological, and antioxidant indicators.