Effects of oregano essential oil on faecalmetabonomics in fattening sheepassessed using LC-MS/MS technology

Twelve Suffolk Ram × Small-tailed Han sheep with similar body weight (20.00 ± 1.27) kg were randomly assigned to 2 treatments (control, oregano essential oil group),6 sheep per group. The control group was fed a basic diet, the oregano essential oil group was fed a basic diet + 7 g·d⁻¹of oregano essential oil, to each sheep, separately. A pre-trial period of 10 d and formal period was 72 d was employed. The feces of the control and oregano essential oil groups were collected at the end of the trialfor screening of differential metabolites by liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology. The results identified multiple differential metabolites, including: 1) Heliangin, CE 22:5 (4Z,7Z,10Z,13Z,16Z), methylguanidine, acadesine, LysoPE (18:1 (9Z)/0:0), N-Acetyl-D-neuraminic acid, cyclohexanecarboxylic acid, 4-methoxyphenylacetic acid, DL-dopa, thymidine, demethoxycurcumin, 5'-methylthioadenosine, 3-hydroxybenzoic acid. A total of 15 differential metabolites were screened by positive and negative ion patternsin the feces of the two groups (∣log2FC∣ > 1,P < 0.01,VIP > 1). Compared with the control group, all metabolites were up-regulated in the oregano essential oil group. 2) The differential metabolite KEGG pathway analyses demonstrated that biosynthesis of terpenoids and steroids, microbial metabolism in diverse environments, phenylalanine, tyrosine and tryptophan biosynthesis, cysteine and methionine metabolism and degradation of aromatic compounds were enriched in the oregano essential oil group (Impact > 0.1). These pathways belonged to lipid metabolism, organic matter metabolism and amino acid metabolism, separately. In conclusion, oregano essential oil may take part in metabolism of lipids, organics and amino acids in fattening sheep, which plays the important role in maintaining health in sheep by regulating metabolic pathway.