Differential metabolites in serum samples before and after VE injection in yak.

(a) Volcano plots of the difference metabolites. Each point in the volcanic map represents a metabolite, red and green dots indicate up-regulated and down-regulated metabolites respectively. Metabolites with no difference are shown in gray. (b) Metabolites are ranked by variable importance in projection analysis (VIP) of respective groups. The top 20 important metabolites were arranged from top to bottom according to intracellular concentration. The red box represents a high concentration of the molecule and the green box represents low concentration.