Effects of yam (Dioscorea oppositifolia L.) on growth performance, serum biochemical level and liver metabonomics of rainbow trout (Oncorhynchus mykiss)

Yam (Dioscorea oppositifolia L.), as an important traditional medicinal herb, has a functional impact upon anti-disease and strengthens immunity. In the present study, we conducted growth performance, serum biochemical level, metabonomics analysis of liver in rainbow trout (Oncorhynchus mykiss) fed diets including yam extract (0, 0.2 %, and 0.4 %) for 56 days, to identify yam extract-affected growth performance, serum biochemical level, liver metabolites and metabolic pathways. After the feeding experiment, there were no significant changes in weight gain rate (WGR) and specific growth rate (SGR) in yam-supplemented groups. Albumin (ALB) and total protein (TP) contents, and superoxide dismutase (SOD) and acid phosphatase (ACP) activities were increased, while alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities were decreased in yam extract groups. Using VIP- values > 1 and P-value < 0.05 as the threshold, a total of 29 and 78 metabolites were significantly up-regulated in 0.2 % and 0.4 % yam extract group, respectively, while 14 and 74 metabolites were significantly down-regulated. Moreover, 18 overlap significantly discriminating metabolites in two comparisons were annotated to 8 metabolic pathways in KEGG analysis, 7 top significantly enriched pathways terms (P < 0.05) include Glycosylphosphatidylinositol (GPI)-anchor biosynthesis, Autophagy-other, Autophagy-animal, Ferroptosis, Glutathione metabolism, Glycerophospholipid metabolism, and Cysteine and methionine metabolism. Results showed that yam extract has certain antioxidant and protective effects on liver of rainbow trout, and the mechanism of this effect may be related to the conversion of Glycerophosphoethanolamine to glycerophosphocholine, down-regulation of canavanine, glutathione metabolism and Cysteine and methionine metabolism pathways.