An eight-week feeding trial was conducted to investigate the effects of dietary
andrographolide on the growth performance,
antioxidant capacity in the liver, intestinal inflammatory response and microbiota of Monopterus albus. A total
of 900 health fish (25.00 ± 0.15 g) were randomly divided into five groups: AD1 (the basal diet) as the control, and AD2, AD3, AD4 and AD5 groups, which were fed the basal diet supplemented with 75, 150, 225 and 300 mg/kg
andrographolide, respectively. The results showed that compared with the control group, dietary
andrographolide supplementation (1) significantly increased
trypsin and
lipase activities in the intestine, and increased the
weight gain rate but not significantly; (2) significantly increased the levels of
glutathione reductase (GR),
glutathione (GSH) and
glutathione peroxidase (GPx) and the content of in the liver; significantly decreased the contents of
reactive oxygen species (ROS) and
malondialdehyde (MDA); remarkably upregulated the Nrf2, SOD1, GSTK and GSTO
mRNA levels in the liver; downregulated the Keap1
mRNA level; (3) significantly increased the villi length and goblet cell numbers in the intestine, remarkably upregulated the
Occludin mRNA level in the intestine, downregulated the
Claudin-15 mRNA level; (4) remarkably upregulated the
IL-10, TGF-β1 and TGF-β3
mRNA levels in the intestine; downregulated the IL-12β and TLR-3
mRNA levels; (5) significantly decreased the richness and diversity of the intestinal microbioma, increased the percentages of Fusobacteria and Firmicutes and significantly decreased the percentages of Cyanobacteria and Proteobacteria. In conclusion, these results showed that dietary low-dose
andrographolide (75 and 150 mg/kg) promoted growth and
antioxidant capacity, regulated the intestinal microbioma, enhanced intestinal physical and immune barrier function in rice field eel.