Effects of two postbiotics (yeast culture and complex probiotics) on growth performance, body composition, liver and intestinal health, and fillet quality of rice field eel (Monopterus albus)

This study explored effects of yeast culture (YC) and complex probiotics (CP) on the growth performance, liver-intestinal health and fillet quality of rice field eel ( Monopterus albus ). 1200 healthy fish with initial weight (23.04 ± 0.04) g were selected and randomly divided into 5 groups (4 replies per group): control group, 0.3 % YC group, 0.6 % YC group, 0.3 % CP group and 0.6 % CP group. Results of 56-d experiment showed that postbiotics could significantly increase final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and reduced feed conversion rate (FCR) ( P < 0.05). Dietary postbiotics reduced the total lipid content in liver ( P < 0.05), increased protein deposition in whole body and muscle ( P < 0.05). Dietary postbiotics also improved liver and intestinal antioxidant ability (total superoxide dismutase, catalase, glutathione peroxidase, glutathione) ( P < 0.05), immune function (serum acid phosphatase, alkaline phosphatase and liver lysozyme activities) ( P < 0.05), and intestinal digestive ability (α-amylase, trypsin) ( P < 0.05). Meanwhile, dietary postbiotics significantly enhanced intestinal villi height and mucosal barrier integrity ( P < 0.05). High-throughput sequencing revealed that, intestinal microbial probiotics (Firmicutes and Bacteroidetes) abundance increased and pathogenic (Proteobacteria) abundance decreased in the postbiotic-treating group ( P < 0.05). It is worth noting that dietary postbiotics could improve muscle quality ( P < 0.05), reduce muscle fibers area and diameter ( P < 0.05), and promote protein deposition ( P < 0.05). In summary, dietary postbiotics can show beneficial effects on growth, liver and intestinal health, and muscle quality in this fish. • Dietary postbiotics (PBT) increased growth performance and protein contents in body. • PBT reduced lipid contents and improved antioxidant and immune activities in liver. • PBT improved intestinal digestive and antioxidant capacity, and mucosal integrity. • PBT regulated intestinal microbiota and permeability. • PBT promoted protein deposition in muscle and enhanced muscle texture properties.