Abstract: In this study, plasma metabolomics change features of Mongolian horses before and after endurance exercise were analyzed by ¹H-NMR technology. Six castrated Mongolian male horses, whose age, body height, body length, heart girth, cannon circumference were (5.33±0.82) years, (136.83±0.75) cm, (143.33±2.58) cm, (157.17±2.04) cm, (18.45±0.27) cm, respectively, were selected to do the endurance exercise of 15 and 30 km by trot pace. In total, 24 blood samples from the 6 Mongolian horses were collected before and after 15 and 30 km distance training, respectively. The spectrum information of plasma metabolite were measured by Bruker AV III ¹H-NMR spectrometer with the resonance frequency of 600.13 MHz. The metabolic patterns and differential metabolic markers between groups were identified using PLS-DA package of R programme and one-dimensional ANOVA test of SPSS 20.0 software, respectively. The results showed that 47 distinct plasma metabolites were identified in 6 Mongolian horses before and after two different loads (15 and 30 km) of exercise. In which, 21 differential plasma metabolites were observed before and after 15 km loading exercise. After 15 km loading exercise, the metabolite concentration of ethanol and mannose decreased; However, the metabolite concentration of glucose, acetoacetate, pyruvate, lactate, creatinine, glycerol, valine, alanine, leucine, tyrosine, phenylalanine, threonine, isobutyrate, methionine, 2-hydroxyisobutyrate, O-acetylcar-nitine, 3-hydroxyisobutyrate, 3-methyl-2-oxovalerat and 3-hydroxyisovalerate increased. Ten differential plasm metabolites were detected before and after 30 km loading exercise. After 30 km loading exercise, the metabolite concentration of ethanol, glucose, lysine, glycine, proline, glutamine, τ-methylhistidine and valine decreased; The metabolite concentration of methanol and creatine increased. Comparison of the metabolite concentration after 15 and 30 km loading exercise showed that alanine, citrate, acetate, lysine, malonate, acetone, 2-hydroxyisovalerate, 2-hydroxyisobutyrate, pantothen, betaine and isobutyrate decreased, lactate, dimethyl sulfone, pyruvate, N-phenylacetylglycine, hippurate, methanol and 3-hydroxyisovalerate increased. In total, 47 distinct plasma metabolites were identified and the types of differential metabolites were significantly different in 6 Mongolian horses before and after 15 and 30 km exercise. The energy supply mode of the 30 km exercise in Mongolian horses is mainly aerobic metabolism of fatty acids, whereas, that of the 15 km exercise is mainly anaerobic metabolism of glycolysis, while ketone body metabolism was a transitional stage of energy supply mode conversion. The results provided a theoretical basis for the training and breeding of endurance racehorses in China.

Key words: Mongolian horse, endurance exercise, metabolomics, ¹H-NMR