Metabolomics of stallion seminal plasma: Identification of potential fertility biomarkers based on differences between high and low pregnancy stallions.

BACKGROUND

The seminal plasma (SP), a fluid originating from the testes, epididymis, and accessory sex glands, represents 98 % of the volume of stallion ejaculate. Metabolomic analysis enables the identification of final products of metabolic pathways, providing insights into reproductive physiology.

OBJECTIVE

This study aimed to investigate the metabolomic profile of stallion seminal plasma and to investigate metabolic differences between stallions with high and low pregnancy rates, in order to identify potential biomarkers associated with fertility.

METHODS

Twenty-four Criollo stallions, were sampled for molecular biology once during the breeding season.

RESULTS

Pregnancy rates at day 16 post-insemination ranged from 20.2 % to 95.6 %, forming two groups: High Pregnancy (HP; ≥60 %) and Low Pregnancy (LP; ≤50 %). Semen was evaluated for concentration, kinetics, morphology, and membrane integrity. Metabolic profiling using UHPLC-QTOF-MS identified 18 metabolites, including acetyl carnitine, carnitine, isoleucine, methylbutanoyl carnitine, ornithine, phenylalanine, tryptophan, taurine, palmitate, lactate, phosphate, oleate, stearate, citrate, fructose, hippurate, 1,3-dioxan-5-ol, and melatonin. Oleate showed higher abundance in LP stallions (P < 0.05), whereas taurine and phosphate were enriched in HP stallions (P < 0.05). Pearson correlation analysis revealed 13 metabolites significantly associated with reproductive outcomes, with phosphate and 1,3-dioxan-5-ol emerging as the most relevant. Phosphate, in particular, was highlighted as a potential fertility biomarker due to its essential role in sperm energy metabolism via pyrophosphate breakdown.

CONCLUSION

These findings elucidate molecular mechanisms underlying subfertility and support the identification of biomarkers for fertility prediction, offering potential applications in reproductive management and optimization strategies for stallions.