Effects of herbal extracts (Foeniculum vulgare and Artemisia annua) on growth, liver antioxidant capacity, intestinal morphology and microorganism of juvenile largemouth bass, Micropterus salmoides

The effects of diets supplement Foeniculum vulgare extract (FE) and Artemisia annua extract (AE), single or combined, on the growth, liver antioxidant capacity and intestinal flora immunity of Micropterus salmoides were investigated. Largemouth bass juvenile (10.77 +/- 0.02 g) were divided into 4 groups and each group was fed with diets supplemented with or without the medicinal herb extracts (additive quantity: 0.05%) for 8 weeks. The results showed that the largemouth bass fed with diets supplemented with AE or a combination of the FE and AE (FAE) significantly enhanced the specific growth rate (SGR) and feed intake (FI). Furthermore, the largemouth bass fed with two medicinal herbs alone or in combination significantly increased the antioxidant enzyme activities (SOD and CAT) and their gene expression levels, and decreased the malondialdehyde (MDA) content in the liver (P < 0.05). In addition, AE supplement also significantly increased the number of intestinal villus, affected the intestinal bacterial structure, increased the abundance of Lactobacillus and Enterococcus, and decreased the abundance of Plesiomonas in the intestine(P < 0.05). Bugbase phenotypic prediction analysis indicated that fish fed with AE remarkably upregulated gram-positive bacteria and downregulated gram-negative bacteria, while potential pathogenicity was obviously reduced (P < 0.05). All in all, this study revealed that AE can enhance the liver antioxidant capacity, improve intestinal morphology and regulate intestinal flora, thus promoting the growth of largemouth bass, and can be used as a feed additive to improve health and promote growth of fish.

Automated summary

This study investigated the effects of Foeniculum vulgare extract (FE) and Artemisia annua extract (AE), either alone or combined, on the growth, liver antioxidant capacity and intestinal flora immunity of Micropterus salmoides. The results showed that diets supplemented with AE or a combination of FE and AE significantly enhanced the growth and feed intake of largemouth bass. Furthermore, the use of these medicinal herb extracts increased antioxidant enzyme activities and decreased oxidative damage in the liver. AE also affected the intestinal bacterial structure, increasing beneficial bacteria and reducing potentially pathogenic bacteria.