Effects of dietary fermented Chinese herbal medicines on growth performance, digestive enzyme activity, liver antioxidant capacity, and intestinal inflammatory gene expression of juvenile largemouth bass (Micropterus salmoides)

This study aimed to evaluate the effects of fermented Chinese herbal medicines (FCHM) on growth performance, digestive enzyme activity, antioxidant capacity and intestinal inflammatory gene expression of juvenile largemouth bass (Micropterus salmoides). Four trial diets H0 (basal diet), H1, H2, and H3 (added 1 %, 3 %, and 5 % FCHM to the basal diet, respectively) were prepared. Fish were randomly divided into 4 treatment groups of 3 replicates per treatment (20 fish/replicate) and reared for 8 weeks. The results of the test showed that: 1) Feeding 1 % FCHM significantly increased the weight gain rate (P < 0.01) and specific growth rate (P < 0.05) of juvenile largemouth bass compared with the control group. 2) Compared with the control group, FCHM had no significant effect on the body composition of juvenile largemouth bass (P > 0.05) but could result in an overall decreasing trend in muscle drip loss, steaming loss, and freezing loss. 3) FCHM significantly increased the activity of SOD, GSH-PX and CAT in the liver of juvenile largemouth bass and decreased the MDA compared to that of the control group (P < 0.01). (4) Compared with the control group, FCHM significantly increased the relative mRNA expression of the intestinal anti-inflammatory factors TGF-β and IL-10 (P < 0.01) and decreased the pro-inflammatory factors IL-8, IL-15 (P < 0.01) and TNF-α (P < 0.05) of juvenile Largemouth bass. In summary, a 1 % FCHM addition amount can improve the growth performance, liver antioxidant and immune capacity of juvenile largemouth bass.