Macleaya cordata extract improves the growth performance and intestinal health of American eels (Anguilla rostrata) farmed in intensive system.

The present study was conducted to evaluate the effects of dietary Macleaya cordata extract (MCE) supplementation on growth performance and intestinal health of American eels (Anguilla rostrata) farmed in intensive system. A total of six cement tanks of fish were randomly divided into a control group fed a commercial diet and an MCE group fed the commercial diet with 100 mg/kg MCE, respectively. There were three replicates in each group. The results suggested that 100 mg/kg MCE could improve the growth performance and intestinal health of the American eels by strengthening the barrier function and antioxidative ability in the intestine and beneficially modulating intestinal microbiota with the higher relative abundance and more species of the potential probiotics and the lower relative abundance of potentially pathogenic bacteria.

Grape seed proanthocyanidin extract regulates lipid metabolism of the American eel (Anguilla rostrata).

The current study was aimed to examine the effect of grape seed proanthocyanidin extract (GSPE) on regulating lipid metabolism of American eels. A total of six cement tanks of fish were randomly divided into a control group fed with a commercial diet and a GSPE group fed with a commercial diet supplemented 400 mg/kg GSPE. There were three replicates in each group. Results suggested that GSPE could decrease the levels of total cholesterol, triglycerides, and low-density lipoprotein cholesterol, and increase the high-density lipoprotein cholesterol level in serum. GSPE might regulate lipid metabolism through upregulating linoleic acid metabolism and arachidonic acid metabolism along with downregulating metabolisms of phenylalanine, tyrosine, and tryptophan biosynthesis and valine, leucine, and isoleucine biosynthesis.

Effects of Dietary Supplementation of Peanut Skin Proanthocyanidins on Growth Performance and Lipid Metabolism of the Juvenile American Eel (Anguilla rostrata).

As a functional feed additive, grape seed proanthocyanidin extract has received a lot of attention due to its biological activity in the health of aquatic animals, but its high cost limits the application of this feed additive in the diet of many fish species. It is thus urgent to develop a new resource of proanthocyanidin extract. We aimed to investigate the effects of dietary supplementation with peanut skin proanthocyanidins (PSPc) on growth parameters and lipid metabolism of juvenile American eel (Anguilla rostrata). Four hundred and fifty juvenile eels were randomly divided into five groups fed diets with five PSPc supplementation levels. The trial lasted for 8 weeks. Dietary PSPc supplementation significantly improved weight gain and feed utilization, and the best growth performance was found in the group fed with 900 mg/kg PSPc. PSPc supplementation significantly affected the crude protein level of whole fish and serum lipid parameters, and the best lipid-lowering effect was found in the fish fed with 900 mg/kg PSPc. Dietary PSPc supplementation increased lipolytic enzyme activities and decrease lipid synthase levels in the liver. The lipid metabolites affected by 900 mg/kg PSPc in the liver were mainly upregulated phosphatidylethanolamine in autophagy, downregulated ceramides in sphingolipid metabolism, upregulated phosphatidylcholine and phosphatidylethanolamine, downregulated 2-lysophosphatidylcholine in glycerophospholipid metabolism, and upregulated phosphatidylcholine in linoleic acid metabolism. In conclusion, an appropriate level of PSPc might effectively improve growth performance and regulate the lipid metabolism of the juvenile American eel, and 900 mg/kg PSPc is recommended in the diet of this fish species.