A metabolomics perspective on 2 years of high-intensity training in horses

Abstract

The plasma metabolomic profile of elite harness horses subjected to different training programmes was explored. All horses had the same training programme from 1.5 until 2 years of age and then high-intensity training was introduced, with horses divided into high and low training groups. Morning blood samples were collected at 1.5, 2, 2.5 and 3.5 years of age. The plasma was analysed using targeted absolute quantitative analysis and a combination of tandem mass spectrometry, flow-injection analysis and liquid chromatography. Differences between the two training groups were observed at 2 years of age, when 161 metabolites and sums and ratios were lower (e.g. ceramide and several triglycerides) and 51 were higher (e.g. aconitic acid, anserine, sum of PUFA cholesteryl esters and solely ketogenic AAs) in High compared with low horses. The metabolites aconitic acid, anserine, leucine, HArg synthesis and sum of solely ketogenic AAs increased over time, while beta alanine synthesis, ceramides and indole decreased. Therefore high-intensity training promoted adaptations linked to aerobic energy production and amino acid metabolism, and potentially also affected pH-buffering and vascular and insulin responses.

Figure 1

Volcano plot of plasma metabolites present in higher (red), lower (blue) and unchanged (black) concentrations in plasma samples from the High group compared with the Low group of 16 Standardbred horses at 2 years of age. Upper left quadrant contains adjusted p values < 0.05 and fold change < − 0.5, upper right quadrant adjusted p values < 0.05 and fold change > 0.5. Abbreviations: aconitic acid (AconAcid), cholesteryl ester (CE), methionine-sulfoxide (Met.SO), ceramides (Cer), polyunsaturated fatty acids (PUFA), amino acids (AA), triglyceride (TG).

Figure 2

Volcano plot of plasma metabolites with Higher (red), lower (blue) and unchanged (black) values at (A) 2 years of age, (B) 2.5 years of age and (C) 3.5 years of age compared with 1.5 years of age for 16 Standardbred horses in training. Upper left quadrant contains adjusted p values < 0.05 and fold change < − 0.5, upper right quadrant adjusted p values < 0.05 and fold change > 0.5. Note different scale on the y-axis in panel A (0–10) compared with B and C (0–40). AconAcid aconitic acid, AA amino acids, AABA alpha-aminobutyric acid, b.Ala beta alanine, C0 carnitine, Cer ceramides, CE cholesteryl ester, DG diglyceride, ADMA asymmetric dimethylarginine, DiCA dodecanedioic acid, FA fatty acid, HexCer hexosylceramides, HArg homoarginine, Leu leucine, PC phosphatidylcholines, SDMA symmetric dimethylarginine, TG triglyceride, Val valine.