Ovarian superstimulatory response and embryo production in mares treated with equine pituitary extract twice daily.
Abstract: Equine pituitary extract (EPE), has been reported to induce multiple ovulation in mares, however ovulation rates are poor in comparison to those obtained in other species. Attempts to improve the effectiveness of EPE for induction of superovulation in cyclic mares has focused on daily frequency of EPE treatment. Two experiments were performed to compare the ovarian response of cyclic mares given EPE once or twice-daily. Mares were assigned to one of two treatment groups 6 to 8 days after ovulation: prostaglandin was given once and EPE (25 mg) was given once daily (Group 1) or twice daily (Group 2). In Experiment 1, more (P or = 35 mm were detected in mares treated with EPE twice daily (6.1 +/- 3.1) than in mares treated once a daily (2.0 +/- 0.6). In a second experiment, the embryo recovery rates of mares given the two EPE protocols used in Experiment 1 were compared. The number of ovulations per mare was higher (P < 0.05) for mares treated twice-daily (7.1 +/- 5.1, range 3 to 18) than for mares treated once daily (2.4 +/- 1.8, range 1 to 6). The number of embryos produced per mare was higher (P < 0.05) in mares in Group 2 (3.5) than in Group 1 (1.6). Although it is not clear whether the increased ovulation rate is due specifically to dose or frequency, twice-daily administration of a high dose of EPE significantly improved follicular development, ovulation and embryo recovery over the standard treatment of once-daily injection.
Publication Date: 2001-10-23 PubMed ID: 11665889DOI: 10.1016/s0093-691x(01)00615-xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research explores the effects of giving equine pituitary extract (EPE) to mares once versus twice daily and found that twice-daily dosage results in better ovulation and embryo production rates.
Introduction
- This study focuses on testing the effects of an equine pituitary extract (EPE) treatment on the ovulation and embryo production rates among mares.
- EPE has been recognized as an inducer of multiple ovulatory responses, yet its effectiveness when compared with those observed in other species has been lower.
- The research was designed to see if increasing the frequency of EPE treatment on a daily basis could improve its effectiveness.
Methods
- Two experiments were carried out, with mares receiving EPE treatment once or twice a day after ovulation.
- Experiment 1 measured the ovarian response of the mares in terms of follicles exceeding 35mm.
- Experiment 2 compared the embryo recovery rates following the same two EPE treatment plans used in Experiment 1.
Results
- Results from Experiment 1 showed that the mares which received the twice-daily treatment had more large follicles compared to the group receiving once-daily treatment.
- In Experiment 2, the mares provided with EPE twice a day had higher ovulations per mare as well as greater embryo counts as compared to those treated once a day.
Conclusion
- Although the study couldn’t precisely identify whether the improved ovulation rate was due to the dosage or the frequency of the treatment, it was clear that the twice-daily administration of a high dose of EPE significantly improved the follicular development, ovulation, and embryo recovery rate over the standard once-daily injection regimen.
Cite This Article
APA
Alvarenga MA, McCue PM, Bruemmer J, Neves Neto JR, Squire EL.
(2001).
Ovarian superstimulatory response and embryo production in mares treated with equine pituitary extract twice daily.
Theriogenology, 56(5), 879-887.
https://doi.org/10.1016/s0093-691x(01)00615-x Publication
Researcher Affiliations
- Department of Animal Reproduction and Veterinary Radiology, School of Veterinary Medicine and Animal Science, UNESP Botucatu, SP, Brazil. malvarenga@fmvz.unesp.br
MeSH Terms
- Animals
- Blastocyst / physiology
- Chorionic Gonadotropin / administration & dosage
- Embryo, Mammalian / physiology
- Female
- Horses / embryology
- Horses / physiology
- Morula / physiology
- Ovarian Follicle / anatomy & histology
- Ovarian Follicle / physiology
- Pituitary Gland / physiology
- Pregnancy
- Superovulation
- Tissue Extracts / administration & dosage
- Tissue Extracts / pharmacology
Citations
This article has been cited 1 times.- Tsukada T, Sato K, Moriyoshi M, Koyago M, Sawamukai Y. Treatment with a High Dose Combination of PMSG/hCG Preparation of Mares Clinically Diagnosed with Ovarian Quiescence during the Breeding Season (Investigation from 1975 to 2000).. J Equine Sci 2008;19(2):35-8.
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