Effects of Solid-State Fermented (SSF) Pelleted Feed with Lactobacillus plantarum on Tachysurus fulvidraco: Growth, Digestion, Antioxidant, Immunity, Intestinal Morphology, and Microbiota

This study aimed to evaluate the effects of solid-state fermented commercial pelleted feed with Lactobacillus plantarum on growth performance, digestive physiology, antioxidant, and immune capacity, as well as morphology and microbiota in intestinal of Tachysurus fulvidraco. A total of 420 fish (49.96 +/- 7.10 g) were randomly allocated to twelve 300 L buckets for a 60 d farming trial. The diets of three treatments were established: the untreated commercial diet (UCD), the commercial diet mixed with fermented liquid (MFLD), and the solid-state fermented commercial diet (SSFD). The results indicated that SSFD treatment had a significant positive effect on the growth performance of T. fulvidraco, with an increase of 15.69% to 16.57% (p < 0.05) compared with UCD and MFLD treatments. MFLD and SSFD treatments also showed higher total anti-oxygen capacity, catalase, and glutathione peroxidase activities in the intestine significantly compared with UCD treatment (p < 0.05). Furthermore, the activities of alkaline phosphatase and lysozyme activities both in the liver and intestine were significantly higher in MFLD and SSFD treatments than in UCD treatment (p < 0.05). The villus height in the midintestine was also greater in MFLD and SSFD treatments compared with UCD treatment (p < 0.05). Regarding the intestinal microbiota, the dominant bacteria in UCD treatment was Cetobacterium, with the highest abundance in whole intestinal segments. However, in MFLD and SSFD treatments, the abundance of Cetobacterium in the foreintestine significantly decreased (p < 0.05). In conclusion, this study elucidates that solid-state fermentation feed may not only improve the digestive capacity, antioxidant ability, immune function, and intestinal morphology of T. fulvidraco to enhance growth performance but also influence intestinal microbial composition. These findings provide beneficial proof for developing fermented feed of T. fulvidraco.