关键词: 杜仲叶; 绵羊; 生化指标; 代谢组学; 特征代谢物

Abstract:

In order to study the effects of Eucommia ulmoides leaves (EUL) on nutrient metabolism and physiological function in sheep,thirty Hu sheep of 70-80 days old and 25-30 kg body weight were chosen and randomly divided into three groups:Control group (diets without EUL,CTL),low level of EUL group (diets with 10% EUL,EUL1) and high level of EUL group (diets with 20% EUL,EUL2).The experiment was last for 90 d with 15 d of adaption.When the experiment approached to the end,the sheep blood sample was collected via jugular vein with 5 mL vacuum tubes of anticoagulant and coagulant,respectively,to extract plasma and serum. The plasma was used to test biochemical indexes, and the serum was used to metabonomics determination base on liquid chromatography-mass spectrometry (LC-MS). The results showed that the level of glucose (GLU),non-esterified fatty acid (NEFA),high density lipoprotein (HDL) and very low density lipoprotein (VLDL) in EUL1 and EUL2 groups were increased at different degree,and these indexes showed significant or extremely significant difference between EUL2 and CTL groups (P<0.05;P<0.01),but there was no significant difference between EUL1 and CTL groups (P>0.05). The cholesterol (TG) in EUL1 and EUT2 groups was significantly increased compared with CTL group (P<0.05),while the urea level was extremely significantly decreased (P<0.01),and there was no significant difference between EUL1 and EUL2 groups (P>0.05). Metabonomics determination of LC-MS found 593 features under positive mode and 1 570 features under negative mode using the serum samples.After analyzing with SIMCA-P software (V.13.0),principal component analysis (PCA),partial least squares discriminant analysis(PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the score plot of the three groups separated markedly meant that the metabolites among the three groups contribute to differentiate them. Further analysis with t test for the features of variable importance in the projection (VIP) value larger than 1.0 (VIP>1.0) found that there were 24 characteristic metabolites were significantly different (P<0.05).These metabolites were involved in metabolism of glucose,fat and protein,most of them were related with the pathway of TCA (tricarboxylic acid) cycle, and some of them were concerned with improving of animal health and immune.In conclusion, this study demonstrated that some special ingredients in Eucommia ulmoides leaves affected metabolism of sheep and altered nutrient metabolic pathway greatly.Eucommia ulmoides leaves was not only a kind of high quality of forage, but also a functional feed regulated animal metabolic and healthy status.

Key words: Eucommia ulmoides leaves; sheep; biochemical indices; metabonomics; characteristic metabolites