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Impact of moderate exercise on ovarian blood flow and early embryonic outcomes in mares.
Abstract: The advent of embryo transfer has allowed horses to continue to train and compete during the breeding season. However, the associated stress of exercise may be detrimental to reproduction. The objectives of this study were to evaluate differing exercise protocols on reproductive blood flow and embryonic outcomes in mares. Light-horse mares were randomized into control (n = 4), partial-exercised (n = 6), and full-exercised (n = 6) groups. Partial-exercised mares were moderately exercised 30 min daily during the periovulatory period and rested after ovulation for 7 d. Full-exercised mares were exercised for 30 min daily throughout the reproductive cycle. Mares were artificially inseminated during estrus and subjected to uterine flush for embryo recovery on d 7 post ovulation. Blood flow through both ovarian arteries and vascular perfusion of the wall of the preovulatory follicle were examined by color Doppler ultrasonography. Results indicated exercise induced greater serum cortisol concentrations (P < 0.05). Embryo recovery rates were reduced in exercised (20/46, 43%) compared with control (14/21, 67%) mares (P < 0.10). When examined separately, embryo recovery rates for partial-exercised (11/25, 44%) and full-exercised (9/21, 43%) mares were not significantly different. Additionally, fewer quality Grade 1 embryos were recovered from partial-exercised mares compared with both control and full-exercised mares (P < 0.05). Blood flow through both ovarian arteries was greater in both exercised groups in the days leading up to ovulation (P < 0.05). However, vascular perfusion of the wall of the preovulatory follicle on the day before ovulation was less in both partial-exercised (45.9 ± 3.0%) and full-exercised (44.8 ± 3.4%) mares vs. control (54.9 ± 3.6%; P < 0.05). In exercised mares, vascular perfusion of the follicle wall was greater when an embryo was recovered (P < 0.01). No differences were found in follicle ovulatory diameter among exercised and non-exercised mares. When groups were combined, follicle diameter was greater when an embryo was recovered (44.9 ± 1.0 mm) compared with an unsuccessful embryo recovery attempt (42.8 ± 0.7 mm; P < 0.05). In conclusion, these data demonstrated that exercise increased ovarian arterial blood flow leading up to ovulation and decreased vascular perfusion of the wall of the preovulatory follicle. Mares given rest the day after ovulation up until an embryo collection attempt did not improve embryo recovery rates.
Publication Date: 2012-06-04 PubMed ID: 22665656DOI: 10.2527/jas.2011-4713Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Randomized Controlled Trial
Summary
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The study explores the effects of different exercise regimes on the reproductive capacity of mares, particularly in relation to ovarian blood flow and embryonic outcomes. It concludes that exercise has a noticeable impact on ovarian arterial blood flow and the vascular perfusion of preovulatory follicles, and even a rest period after ovulation doesn’t improve embryonic recovery rates.
Study Design and Methodology
The mares involved in the study were divided into three groups: control (no exercise), partial exercise, and full exercise. The partial exercise group engaged in 30 minutes of moderate exercise daily during the periovulatory period and then were rested for seven days after ovulation. The full exercise group engaged in 30 minutes of daily exercise throughout the reproductive cycle. Both of these exercise regimes were compared to a control group that didn’t exercise.
All the mares were artificially inseminated during estrus and subjected to a process called uterine flush for embryo recovery approximately seven days post ovulation. Researchers used color Doppler ultrasonography to evaluate blood flow through the ovarian arteries and to assess vascular perfusion of the wall of preovulatory follicles.
Findings
The results of the study revealed several key findings:
- Exercise resulted in higher serum cortisol concentrations (a hormone linked to stress response).
- The rate of embryo recovery was reduced in exercised mares compared to the control group.
- There was no significant difference in embryo recovery rates between the partially and fully exercised mares.
- Quality Grade 1 embryos were recovered less frequently from the partially exercised mares compared to control and fully exercised mares.
- Exercise increased blood flow through both ovarian arteries leading up to ovulation.
- Vascular perfusion of the wall of the preovulatory follicle was reduced in both fully exercised and partially exercised mares compared to control group.
- When an embryo was successfully recovered, vascular perfusion of the follicle wall was found to be greater.
- There was no significant difference in follicle ovulatory diameter among exercised and non-exercised mares.
- When groups were combined, follicle diameter was greater when an embryo was recovered compared to unsuccessful recovery attempts.
Conclusion
The results showed that moderate exercise can increase ovarian arterial blood flow and, at the same time, decrease vascular perfusion of the wall of the preovulatory follicle. Contrary to expectations, resting mares after ovulation did not improve embryo recovery rates. This study suggests that exercise could have potential negative effects on equine reproduction, particularly the production and harvesting of quality embryos.
Cite This Article
APA
Smith RL, Vernon KL, Kelley DE, Gibbons JR, Mortensen CJ.
(2012).
Impact of moderate exercise on ovarian blood flow and early embryonic outcomes in mares.
J Anim Sci, 90(11), 3770-3777.
https://doi.org/10.2527/jas.2011-4713 Publication
Researcher Affiliations
- Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
MeSH Terms
- Animals
- Female
- Horses / embryology
- Horses / physiology
- Ovary / blood supply
- Ovulation
- Physical Conditioning, Animal
- Pregnancy
Citations
This article has been cited 5 times.- Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB. Heat stress in horses: a literature review. Int J Biometeorol 2023 Jun;67(6):957-973.
- Miller N, Pasternak Y, Herzberger EH, Gluska H, Dorenstein C, Rahav R, Hemi R, Zada N, Wiser A. High physical activity and ovarian reserve: a prospective study of normo-ovulatory professional athletes. J Ovarian Res 2022 Sep 16;15(1):107.
- Yousefi B, Baradaran R, Mokhtari T, Semnani V, Sameni H. Maternal aerobic running during mid or late gestation improves the quality of oogenesis and folliculogenesis in the ovary of neonatal rats: An experimental study. Int J Reprod Biomed 2021 Sep;19(9):811-820.
- 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).
- Campbell ML. Embryo transfer in competition horses: Managing mares and expectations. Equine Vet Educ 2014 Jun;26(6):322-327.
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