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Reproduction (Cambridge, England)2023; 165(6); M1-M10; doi: 10.1530/REP-22-0490

Temporal trends in equine sperm progressive motility: a systematic review and meta-regression.

Abstract: Adverse trends in reproductive function are a concern in humans, companion, livestock, and wildlife species. This study indicates that equine populations are at risk of a comparable decline in sperm progressive motility. There is increasing evidence reporting geographically sensitive adverse trends in human semen quality, with parallel trends observed in the dog sentinel. Despite significant economic and welfare complications associated with poor testicular function, trends in current equine populations are undetermined. Given the predictive value of sperm progressive motility (PMOT) in male factor infertility and fertilisation potential, research determining trends in this parameter is warranted. This research analysed trends in stallion sperm PMOT through systematic review and meta-regression. Using a comprehensive search strategy, Scopus, Embase (Ovid), Medline (Ovid), and VetMed (CAB direct) were scoped for eligible data. Using best practices, 230 meta-data points from 229 articles published from 1991 to 2021 were collated for meta-regression analysis. Sperm PMOT declined significantly between 1984 and 2019 (simple linear regression: b -0.340, P = 0.017; meta-regression: b -0.610, P ≤ 0.001). Overall and yearly PMOT declines were predicted at 33.51 and 0.96%, respectively (1984: 63.69 ± 5.07%; 2019: 42.35 ± 3.69%). Trends remained consistent irrespective of sensitivity analyses. Yearly and overall declines were stronger in western (yearly: 0.75%, overall: 26.29%) compared to non-western (yearly: 0.46%, overall: 10.65%) populations. Adverse trends contribute vital data to the debate surrounding declining semen quality, supporting the use of equines as novel comparative models for human reproduction. Results could have significant economic, health, and welfare consequences for equine breeding sectors. A comparable decline in human, dog, and horse sperm quality is indicative of a common environmental aetiology, indicating the need for a holistic One Health approach in determining causes and developing preventative strategies.
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Publication Date: 2023-05-02 PubMed ID: 37000597PubMed Central: PMC10235923DOI: 10.1530/REP-22-0490Google Scholar: Lookup
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  • Systematic Review
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research examined trends in horse sperm progressive motility over time and found a significant decrease, suggesting potential environmental causes and implications for horse breeding and human reproductive research.

Introduction and Goal

  • The researchers set out to explore trends in horse sperm progressive motility (the ability of sperm cells to move forward) which is an indicator of fertility and has implications on successful breeding.
  • Decreases in sperm quality have been observed in humans and canine species, and this study aimed to identify if a similar trend is present in horses.
  • The importance of this endeavour is underscored by it’s impact on economic and welfare issues in the equine industry, while also providing valuable data for human reproductive studies.

Methodology

  • The research was conducted using a systematic review and meta-regression methodology, which involved using extensive search strategies to gather relevant data from Scopus, Embase (Ovid), Medline (Ovid) and VetMed (CAB direct).
  • A substantial database of 230 meta-data points collected from 229 articles published between 1991 and 2021 were utilized for the meta-regression analysis.

Findings

  • Analysis showed a significant decline in sperm progressive motility in stallions between 1984 and 2019.
  • Projected overall and yearly declines were 33.51% and 0.96%, respectively.
  • These adverse trends remained consistent irrespective of sensitivity analyses, and were stronger in Western populations.
  • The data corroborates theories of decreasing semen quality across different species, supporting the potential use of horses as comparative models for studying human reproduction.

Implications and Conclusion

  • This worrying trend could have far-reaching economic and welfare impacts on the equine breeding industry.
  • The presence of a similar decline across humans, dogs, and horses suggests a common environmental factor which should be further investigated to develop preventative strategies.
  • This research further highlights the importance of adopting a comprehensive ‘One Health’ approach – viewing human and animal health as interconnected, in studying causes and solutions for declining reproductive health.

Cite This Article

APA
Harris IT, Maddock C, Farnworth M, Nankervis K, Perrett J, Pyatt AZ, Blanchard RN. (2023). Temporal trends in equine sperm progressive motility: a systematic review and meta-regression. Reproduction, 165(6), M1-M10. https://doi.org/10.1530/REP-22-0490

Publication

Reproduction (Cambridge, England)
ISSN: 1741-7899
NlmUniqueID: 100966036
Country: England
Language: English
Volume: 165
Issue: 6
Pages: M1-M10

Researcher Affiliations

Harris, I T
  • HE Equine, Hartpury University and Hartpury College, Hartpury House, Gloucester, UK.
Maddock, C
  • HE Equine, Hartpury University and Hartpury College, Hartpury House, Gloucester, UK.
Farnworth, M
  • The Jeanne Marchig International Centre for Animal Welfare Education, The Royal (Dick) School of Veterinary Studies, Midlothian, UK.
Nankervis, K
  • HE Equine, Hartpury University and Hartpury College, Hartpury House, Gloucester, UK.
Perrett, J
  • International Office, Veterinary Medicines Directorate, Addlestone, UK.
Pyatt, A Z
  • International Office, Veterinary Medicines Directorate, Addlestone, UK.
Blanchard, R N
  • School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Loughborough, UK.

MeSH Terms

  • Male
  • Horses
  • Animals
  • Humans
  • Dogs
  • Semen Analysis / veterinary
  • Semen
  • Sperm Motility
  • Spermatozoa
  • Infertility, Male
  • Sperm Count

Conflict of Interest Statement

The authors declare that there is no conflict of interest.

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