Plasma metabolomic profiling during peri-parturition in healthy Thoroughbred mares.

Background: Accurate prediction of the timing of parturition is crucial to ensure the health and well-being of both mares and foals. However, equine pregnancies are characterised by significant variability in gestation length, unique endocrine mechanisms, and subtle physiological changes before parturition.

Objectives: To investigate the characteristic changes in the peripheral metabolites of mares before and after parturition using metabolomic approaches.

Study design: Longitudinal in vivo metabolic study.

Methods: Plasma samples (n = 95) were collected from successfully foaling Thoroughbred mares (n = 9) from 4 days before to 7 days after parturition, and a non-targeted metabolomic analysis was performed using GC-MS. PCA and hierarchical clustering analysis were used to compare different groups. Repeated measures ANOVA (RMANOVA) was employed to identify the various metabolites. Enrichment analysis was performed to find the related metabolomic pathways.

Results: PCA and hierarchical clustering analysis demonstrated cluster separation between pre-parturition, parturition, and post-parturition. RMANOVA revealed significant differences in 62 metabolites across all time points (False Discovery Rate <0.05). These metabolites were significantly enriched in multiple metabolic pathways, including valine, leucine, and isoleucine biosynthesis; galactose metabolism; arginine biosynthesis; valine, leucine, and isoleucine degradation; alanine, aspartate, and glutamate metabolism; glyoxylate and dicarboxylate metabolism; and pantothenate and CoA biosynthesis. Among these metabolites, glycerol-3-phosphate (G3P) showed interesting changes that increased 3 days before parturition.

Main limitations: The number of animals and samples included in this study was limited, and the reproductive history of the mares was not considered. In addition, this study did not conduct quantitative research to determine the specific concentrations and ranges of the key metabolites.

Conclusions: G3P is a potential biomarker for predicting parturition. This research provides new insights into mares' periparturition blood metabolic changes.