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Theriogenology2011; 76(4); 615-622; doi: 10.1016/j.theriogenology.2011.03.014

Exercise affects both ovarian follicular dynamics and hormone concentrations in mares.

Abstract: The objectives were to evaluate the effects of exercise on ovarian folliculogenesis and related hormones in mares. Mares (n = 11) were randomly assigned into a control (non-exercised) or treatment (exercised) group. Treatment mares (n = 5) were moderately exercised for 30 min, 6 d/wk. All mares underwent daily transrectal ultrasonographic examinations and ovarian follicles > 6 mm were measured. Blood samples were collected during the first (Cycle 1) and last (Cycle 4) cycle, and serum concentrations of cortisol, LH, and FSH were determined. Mean cortisol concentrations were elevated (P < 0.05) in exercised mares, 6.29 ± 0.22 compared with 5.62 ± 0.16 ng/dL (mean ± SEM), 30 min post exercise. There were no significant differences between groups in mean FSH concentrations; however, exercised mares had lower (17.3 ± 6.4 vs 41.1 ± 5.5 ng/mL; P < 0.05) peak LH concentrations. Furthermore, exercised mares experienced a longer (24.7 ± 0.8 vs 22.2 ± 0.8 d; P < 0.05) mean interovulatory interval for all cycles combined, fewer (P < 0.05) follicles 6 to 20 mm in diameter, and an increased (P 20 mm following deviation. The dominant and largest subordinate follicle in exercised mares had a greater (P < 0.05) mean diameter on the day of deviation, suggesting delayed deviation. Exercised mares also tended (P = 0.06) to have an increased number of cycles with at least two dominant follicles compared to control (62 vs 36%, respectively), indicating a decreased ability of the largest follicle to assert dominance. Under the conditions of this study, moderately exercising mares induced higher cortisol concentrations, lowered peak LH concentrations, and altered ovarian follicular dynamics.
Copyright © 2011 Elsevier Inc. All rights reserved.
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Publication Date: 2011-04-16 PubMed ID: 21497892DOI: 10.1016/j.theriogenology.2011.03.014Google Scholar: Lookup
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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 investigates the effects of exercise on the ovarian function and associated hormone levels in mares. It demonstrates that moderate exercise can influence stress hormone levels and interrupt normal ovarian activities, specifically by extending the interovulatory interval, reducing the number of small and medium-sized follicles, and increasing larger follicles.

Research Methodology

  • The study involved 11 mares, which were randomly divided into two groups – a control group which did not undergo exercise, and a treatment group that was exposed to moderate exercise for 30 minutes, six days a week.
  • Both groups underwent daily transrectal ultrasonographic exams, with ovarian follicles larger than 6mm being measured.
  • Blood samples were collected during the first and last cycle of the experiment. These were used to determine the serum concentrations of cortisol, luteinizing hormone (LH), and follicle-stimulating hormone (FSH).
  • The outcomes were then compared between the groups to determine the effects of exercise on ovarian follicular dynamics.

Research Findings

  • The cortisol levels (stress hormones) were significantly higher in the exercised mares. However, there was no significant change in the FSH levels between the two groups.
  • The levels of LH were found to be lower in the exercised mares, suggesting that exercise could impact the standard ovulatory process.
  • Exercised mares showed a longer average interovulatory interval, implying that exercise had extended the usual period between two ovulations.
  • There was a decrease in the number of 6-20mm follicles and an increase in the number of larger (>20mm) follicles in the exercised mares, suggesting that exercise had led to abnormal follicle growth and development.
  • There was a tendency for increased incidences of multiple dominant follicles in exercised mares, indicating a decrease in the normal dominance of the largest follicle in the ovary.

Conclusion

  • The study concludes that moderate exercise can significantly affect ovarian function and related hormone concentrations in mares.
  • The findings indicate that exercise can induce higher cortisol levels, lower LH concentrations, and alter ovarian follicular dynamics. This could potentially influence fertility and reproductive performance in mares.

Cite This Article

APA
Kelley DE, Gibbons JR, Smith R, Vernon KL, Pratt-Phillip SE, Mortensen CJ. (2011). Exercise affects both ovarian follicular dynamics and hormone concentrations in mares. Theriogenology, 76(4), 615-622. https://doi.org/10.1016/j.theriogenology.2011.03.014

Publication

Theriogenology
ISSN: 1879-3231
NlmUniqueID: 0421510
Country: United States
Language: English
Volume: 76
Issue: 4
Pages: 615-622

Researcher Affiliations

Kelley, D E
  • Department of Animal Sciences, University of Florida, Florida, USA. dekelle@ufl.edu
Gibbons, J R
    Smith, R
      Vernon, K L
        Pratt-Phillip, S E
          Mortensen, C J

            MeSH Terms

            • Animals
            • Chi-Square Distribution
            • Estrous Cycle / physiology
            • Female
            • Follicle Stimulating Hormone / blood
            • Horses / blood
            • Horses / physiology
            • Hydrocortisone / blood
            • Luteinizing Hormone / blood
            • Ovarian Follicle / diagnostic imaging
            • Ovarian Follicle / physiology
            • Ovulation / physiology
            • Physical Conditioning, Animal
            • Random Allocation
            • Ultrasonography

            Citations

            This article has been cited 5 times.
            1. Benammar A, Derisoud E, Vialard F, Palmer E, Ayoubi JM, Poulain M, Chavatte-Palmer P. The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?. Animals (Basel) 2021 Aug 4;11(8).
              doi: 10.3390/ani11082304pubmed: 34438761google scholar: lookup
            2. Satué K, Fazio E, Muñoz A, Medica P. Endocrine and Electrolyte Balances during Periovulatory Period in Cycling Mares. Animals (Basel) 2021 Feb 17;11(2).
              doi: 10.3390/ani11020520pubmed: 33671405google scholar: lookup
            3. Rahayu FK, Dwiningsih SR, Sa'adi A, Herawati L. Effects of different intensities of exercise on folliculogenesis in mice: Which is better?. Clin Exp Reprod Med 2021 Mar;48(1):43-49.
              doi: 10.5653/cerm.2020.03937pubmed: 33648044google scholar: lookup
            4. Campbell ML. Embryo transfer in competition horses: Managing mares and expectations. Equine Vet Educ 2014 Jun;26(6):322-327.
              doi: 10.1111/eve.12182pubmed: 25977596google scholar: lookup
            5. Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM. Effect of breeding season and age on follicular dynamics and hemodynamics in embryo donor mares subjected to luteolysis after embryo flushing. Open Vet J 2024 Mar;14(3):852-865.
              doi: 10.5455/OVJ.2024.v14.i3.13pubmed: 38682132google scholar: lookup
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