Aspiration of oocytes from transitional, cycling, and pregnant mares.
Abstract: The aim of this study was to compare the efficacy of three approaches for recovering equine oocytes via transvaginal ultrasound-guided follicular aspiration. Fourteen mares were used as oocyte donors during the spring transition period and physiologic breeding season, and 11 mares were bred for use as oocyte donors during early gestation. In all mares, large (>20 mm) and small (10-20 mm) follicles were aspirated in eight rounds every 10-11 days. In each of the four rounds during the transition period, half the mares received 12.5 mg eFSH once daily for 4 days prior to aspiration. For each of the four rounds during the cycling season, half the mares received 12.5 mg eFSH twice daily for 3 days prior to aspiration. Pregnant mares were aspirated on days 25, 40 and 55 of gestation and received no eFSH. There were more large (>20 mm) follicles in cycling controls (2.25+/-0.27) and cycling FSH-treated (2.64+/-0.27) mares than in transitional FSH-treated mares (1.18+/-0.27). The number of oocytes recovered from small (10-20 mm) follicles varied by mare (P<0.05) and averaged 1.08+/-0.22 per aspiration for transitional mares and 1.23+/-0.22 per aspiration for cycling mares (P>0.1). The number of oocytes per aspiration from large follicles was greater in cycling FSH-treated mares (0.46+/-0.09) than in transitional control mares (0.11+/-0.09). In pregnant mares, more large follicles were present at day 25 than at any other time, and the number of oocytes per aspiration from large follicles was greater at day 25 (0.73+/-0.16) than at day 55 (0.04+/-0.18). When compared across all seasons and treatments, the day 25 pregnant mares yielded the greatest number of oocytes per aspiration (2.91+/-0.66 per mare).
Publication Date: 2006-08-30 PubMed ID: 16938415DOI: 10.1016/j.anireprosci.2006.07.009Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study examined the effectiveness of three oocyte (egg cell) recovery methods from mares during different stages such as transition period, breeding season, and early gestation. The highest retrieval rate was achieved from pregnant mares on the 25th day of their gestation period.
Understanding the Research
In the attempt to understand the optimal period for the recovery of equine oocytes, the study used different time frames and hormonal treatment methods:
- A total of 14 mares were utilized as oocyte donors during the spring transition period and the physiological breeding season, while 11 mares were bred to donate during early gestation.
- Both small and large follicles were aspired in eight repeated rounds every 10-11 days from all the mares.
- Half of the mares in each group were treated with daily doses of the FSH (Follicle Stimulating Hormone) for a certain period before the oocyte aspiration.
Outcomes of the Study
The study found varying results based on the stage at which the oocyte collection was done and the FSH treatment:
- There were more large follicles in the control mares during the cycling season and those treated with FSH, than in transitional FSH-treated mares.
- Results showed a significant difference in the number of oocytes recovered from the small follicles between individual mares but the difference between the aspiration averages for the transitional and cycling mares was not statistically significant.
- The number of oocytes from large follicles was greater in mares treated with FSH during the cycling season than in the control group during the transition period.
- In pregnant mares, more large follicles were found at day 25 than at any other time, and the number of oocytes per aspiration from large follicles was greater at day 25 than at day 55.
- The highest number of oocytes per aspiration (2.91±0.66 per mare) was recorded in pregnant mares on the 25th day of gestation.
Conclusion
The findings of this study suggest that the time of aspiration and hormonal treatment can have significant impacts on the number of oocytes retrieved from mares. Most notably, it was observed that pregnant mares on day 25 of gestation yielded the greatest number of oocytes, indicating that this might be the optimal time for oocyte harvesting from mares. Future research could further explore this finding and its practical implications in equine reproduction.
Cite This Article
APA
Purcell SH, Seidel GE, McCue PM, Squires EL.
(2006).
Aspiration of oocytes from transitional, cycling, and pregnant mares.
Anim Reprod Sci, 100(3-4), 291-300.
https://doi.org/10.1016/j.anireprosci.2006.07.009 Publication
Researcher Affiliations
- Animal Reproduction and Biotechnology Lab, Colorado State University, Fort Collins, CO 80523-1683, USA.
MeSH Terms
- Animals
- Estrous Cycle / physiology
- Female
- Horses / physiology
- Oocytes / physiology
- Ovarian Follicle / physiology
- Pregnancy
- Tissue and Organ Harvesting / methods
- Tissue and Organ Harvesting / veterinary
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