Dietary prebiotic inulin benefits on growth performance, antioxidant capacity, immune response and intestinal microbiota in Pacific white shrimp (Litopenaeus vannamei) at low salinity

Dietary manipulation is a useful approach to improve production and health of farmed shrimp. However, no study has investigated the effect of prebiotic inulin on intestinal microbiota response and physiological status of shrimp at low salinity of 3 psu (practical salinity unit). The effects of dietary inulin additive at 0%, 0.1%, 0.2%, and 0.4% on growth performance, antioxidant capacity, immune response and intestinal microbiota of Pacific white shrimp (Litopenaeus vannamei) at a low salinity of 3 psu were evaluated after an 8-week feeding trial. Shrimp fed the 0.2% and 0.4% inulin diet significantly increased final weight, weight gain, specific growth rate compared to those fed the control diet. Body ash content tended to increases with the increasing level of inulin. Intestinal amylase and hepatopancreas superoxide dismutase (SOD) activity in 0.4% inulin group were higher than in control group. The acid phosphatase (ACP) and phenol oxidase (PO) activities of hepatopancreas were significantly increased in 0.2% and 0.4% inulin group, respectively, compared to control group. Shrimp fed the 0.2% and 0.4% inulin diet reduced hepatopancreas oxidative stress by increasing the catalase (CAT) activity and decreasing the malondialdehyde (MDA) content compared to those fed the control diet. Shrimp fed 0.4% inulin changed intestinal microbiota by increasing the relative abundance of Firmicutes phylum and Bacillus genus. PICRUSt analysis show that the KEGG pathway involved in aldosterone-regulated sodium reabsorption was significantly increased in shrimp fed 0.4% inulin. The shrimp fed 0.4% inulin exhibited more negative interspecies interactions than those fed the control diet. This study suggests that inulin can serve as a potential feed additive that helps shrimp to cope with low salinity stress.