Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares.
Abstract: Sixty light-horse, nonlactating mares were used to compare the efficacy of equine pituitary extract versus follicle stimulating hormone (FSH-P) for inducing multiple ovulations. On Day 12 of diestrus, mares were assigned to receive 1) no treatment, controls; 2) subcutaneous injections of 750 Fevold rat units of equine pituitary extract once daily; or 3) intramuscular injection of 150 mg of FSH-P twice daily. Ultrasound was used twice daily to visualize follicular changes and ovulation. For mares in Groups 2 and 3, treatment was initiated when two or more follicles > 20 mm were detected, and it continued until all large follicles (> 30 mm) had ovulated or regressed. Five milligrams of prostaglandin F(2)alpha (PGF(2)) were administered to mares in Groups 2 and 3 on the first day of treatment. Human chorionic gonadotropin (3,300 IU) was given to all groups of mares during estrus when a 35-mm follicle was detected. Ovulation rate was greater (P < 0.05) for mares treated with pituitary extract (2.2) compared to FSH-P treatment (1.6) or no treatment (1.0). Thirteen of 18 mares treated with the extract had more than one ovulation versus only four of nine FSH-treated mares. Mares in the pituitary extract group were given injections for an average of 6.4 d compared to 6.8 d (13.7 injections) for FSH-treated mares. Intervals to estrus and ovulation from initial injection of extract were 2.9, 7.6; and 2.6, 9.2 d for FSH-treated mares. The mean number of medium-sized follicles (25 to 30 mm) was greater (P < 0.05) in extract-treated mares compared to the FSH-treated mares. Both extract and FSH increased (P 30 mm and the size of the second largest follicle 1 and 2 d prior to ovulation when compared to controls. Overall, mares with multiple ovulations had more (P 30 mm on Day -6 through -1 (Day 0 = day of ovulation) than single ovulating mares. Those mares that had multiple ovulations had less (P < 0.05) size difference between the largest and second largest follicle when compared to single ovulating mares. In summary, FSH-P at the one dose studied was less effective than equine pituitary extract in inducing follicular activity and multiple ovulation in the mare.
Publication Date: 1986-11-01 PubMed ID: 16726233DOI: 10.1016/0093-691x(86)90174-3Google Scholar: Lookup
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Summary
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The research study investigates the effectiveness of equine pituitary extract and follicle stimulating hormone in inducing multiple ovulations in light-horse, nonlactating mares, and concludes that equine pituitary extract was more effective than follicle stimulating hormone in producing such results.
Methodology
- For the study, sixty light-horse, nonlactating mares were categorized into three groups: a control group receiving no treatment, a group receiving daily subcutaneous injections of 750 Fevold rat units of equine pituitary extract, and another group receiving 150 mg of Follicle Stimulating Hormone (FSH-P) twice daily.
- Ultrasound technology was utilized twice a day to monitor changes in follicular activity and the occurrence of ovulation. Treatment began when the presence of two or more follicles greater than 20mm was detected and continued until all large follicles (greater than 30mm) had either ovulated or regressed.
- On the first day of treatment, mares in the second and third groups were given 5 milligrams of prostaglandin F(2)alpha (PGF(2)) injections. Upon detection of a 35-mm follicle during estrus, all groups were administered with Human chorionic gonadotropin (3,300 IU).
Results
- The ovulation rate observed was considerably higher for mares treated with pituitary extract (2.2) compared to those treated with FSH-P (1.6) or no treatment (1.0). The number of mares that had more than one ovulation was significantly larger in the group treated with pituitary extract than in the FSH-treated group.
- The report also highlights the overall duration of treatment, with the mares in the pituitary extract group undergoing injections for an average of 6.4 days compared to 6.8 days for FSH-treated mares. The intervals to estrus and ovulation from the first injection of extract were also recorded.
- Furthermore, the mean number of medium-sized follicles (25 to 30 mm) was found to be higher in mares treated with pituitary extract than in those treated with FSH. Both treatments increased the number of follicles greater than 30mm and the size of the second largest follicle one and two days before ovulation compared to the control group.
- Mares with multiple ovulations had more follicles of 25 to 30mm and greater than 30mm size from Day -6 through -1 (Day 0 representing the day of ovulation) compared to single ovulating mares. Moreover, these mares exhibited a smaller size difference between the largest and second largest follicle relative to single ovulating mares.
Conclusion
- The research study concludes that at the one dose studied, FSH-P was less effective than equine pituitary extract in inducing follicular activity and multiple ovulation in mares.
Cite This Article
APA
Squires EL, Garcia RH, Ginther OJ, Voss JL, Seidel GE.
(1986).
Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares.
Theriogenology, 26(5), 661-670.
https://doi.org/10.1016/0093-691x(86)90174-3 Publication
Researcher Affiliations
- Animal Reproduction Laboratory Colorado State University Fort Collins, CO 80523 USA.
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