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Home / Equine Research Bank / PLoS One / Ejaculate Characteristics Depend on Social Environment in th...
PloS one2015; 10(11); e0143185; doi: 10.1371/journal.pone.0143185

Ejaculate Characteristics Depend on Social Environment in the Horse (Equus caballus).

Abstract: Sperm competition theory predicts semen characteristics to be affected by the social environment. We used the polygamous horse (Equus caballus) to experimentally study within-subject plasticity in response to different social environments. Stallions were sequentially exposed, over a period of 8 weeks each, to other stallions and then singly to mares, or vice versa (in adjacent boxes separated by grills). Ejaculates were collected to determine semen characteristics. Highest sperm numbers were found in stallions that were first exposed to other stallions and then to mares, while lowest sperm numbers were observed in stallions that had been exposed to mares but not yet to other stallions. One of three sperm velocity measures (curvilinear velocity) was consistently elevated in stallions that were first exposed to stallions and then to mares. Sperm number after exposure to mares and curvilinear sperm velocity after exposure to stallions were both positively correlated to average blood testosterone levels during the corresponding period of exposure. We conclude that ejaculate characteristics are plastic traits affected by the social environment in horses.
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Publication Date: 2015-11-24 PubMed ID: 26599821PubMed Central: PMC4658062DOI: 10.1371/journal.pone.0143185Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

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 study shows that the characteristics of a horse’s semen, including sperm numbers and velocity, change depending on the horse’s social environment, particularly the sequence of exposure to other stallions and mares.

Objective of the Study

The study had two main goals:

  • To provide evidence to support sperm competition theory, which predicts that semen characteristics would be influenced by the animal’s social environment
  • To investigate the within-subject plasticity in horses in response to different social environments

    • Methods

    To achieve these goals, the researchers:

    • Used a polygamous horse species (Equus caballus) as the subject of their study
    • Exposed these horses to different social environments. Specifically, the horses were exposed, for eight weeks each, first to other stallions and then to mares, or vice versa
    • Collected and analyzed the horses’ ejaculates during these exposure periods to determine semen characteristics

      • Findings

      The results of the study were as follows:

      • The highest sperm numbers were found in stallions that were first exposed to other stallions and then to mares
      • The lowest sperm numbers were seen in stallions that were exposed to mares but had yet not been exposed to other stallions
      • One of the three sperm velocity measures (curvilinear velocity) was consistently higher in stallions that were first exposed to stallions and then to mares
      • The number of sperm after exposure to mares, and curvilinear sperm velocity after exposure to other stallions, both showed a positive correlation with average blood testosterone levels during the corresponding exposure period

        • Conclusion

        Based on the findings, the researchers concluded that:

        • Ejaculate (semen) characteristics are plastic traits – traits that can change according to the environment – in horses
        • Social environment, particularly the order of exposure to mares and stallions, influences these characteristics
        • The study’s results support the sperm competition theory

Cite This Article

APA
Burger D, Dolivo G, Wedekind C. (2015). Ejaculate Characteristics Depend on Social Environment in the Horse (Equus caballus). PLoS One, 10(11), e0143185. https://doi.org/10.1371/journal.pone.0143185

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 10
Issue: 11
Pages: e0143185
PII: e0143185

Researcher Affiliations

Burger, Dominik
  • Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland.
Dolivo, Guillaume
  • Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland.
Wedekind, Claus
  • Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland.

MeSH Terms

  • Animals
  • Ejaculation
  • Horses
  • Male
  • Semen
  • Sexual Behavior, Animal
  • Social Environment
  • Sperm Count
  • Sperm Motility
  • Testosterone / blood

Conflict of Interest Statement

The authors have declared that no competing interests exist.

References

This article includes 52 references

Citations

This article has been cited 7 times.
  1. Gacem S, Valverde A, Catalán J, Yánez Ortiz I, Soler C, Miró J. A New Approach of Sperm Motility Subpopulation Structure in Donkey and Horse. Front Vet Sci 2021;8:651477.
    doi: 10.3389/fvets.2021.651477pubmed: 34113670google scholar: lookup
  2. Ponthier J, Rigaux G, Parrilla-Hernandez S, Egyptien S, Gatez C, Carrasco Leroy C, Deleuze S. Case Report: Suppression of Harem Stallion Behavior and Fertility Following Anti-Gonadotropin-Releasing Hormone Vaccination of a Captive Wild Przewalski's Horse (Equus ferus przewalskii). Front Vet Sci 2020;7:569185.
    doi: 10.3389/fvets.2020.569185pubmed: 33330690google scholar: lookup
  3. Rubessa M, Feugang JM, Kandel ME, Schreiber S, Hessee J, Salerno F, Meyers S, Chu I, Popescu G, Wheeler MB. High-throughput sperm assay using label-free microscopy: morphometric comparison between different sperm structures of boar and stallion spermatozoa. Anim Reprod Sci 2020 Aug;219:106509.
    doi: 10.1016/j.anireprosci.2020.106509pubmed: 32828395google scholar: lookup
  4. Jeannerat E, Janett F, Sieme H, Wedekind C, Burger D. Quality of seminal fluids varies with type of stimulus at ejaculation. Sci Rep 2017 Mar 13;7:44339.
    doi: 10.1038/srep44339pubmed: 28287188google scholar: lookup
  5. García-Vázquez FA, Gadea J, Matás C, Holt WV. Importance of sperm morphology during sperm transport and fertilization in mammals. Asian J Androl 2016 Nov-Dec;18(6):844-850.
    doi: 10.4103/1008-682X.186880pubmed: 27624988google scholar: lookup
  6. Burger D, Dolivo G, Marti E, Sieme H, Wedekind C. Female major histocompatibility complex type affects male testosterone levels and sperm number in the horse (Equus caballus). Proc Biol Sci 2015 May 22;282(1807):20150407.
    doi: 10.1098/rspb.2015.0407pubmed: 25904670google scholar: lookup
  7. Hurd JA, Watanabe YL, Toben GJ, Ford AK, Miller CA, Sergott CE, Kelley D, Donaldson ZR, McCullagh EA. Exposure to novel females increases fecundity in adult male prairie voles. bioRxiv 2024 Dec 20;.
    doi: 10.1101/2024.12.18.627569pubmed: 39763992google scholar: lookup
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