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Squires EL, Garcia RH, Ginther OJ, et al. Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares. Theriogenology. 1986;26(5):661-70doi: 10.1016/0093-691x(86)90174-3.
Squires, E. L., Garcia, R. H., Ginther, O. J., Voss, J. L., & Seidel, G. E. (1986). Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares. Theriogenology, 26(5), 661-70. https://doi.org/10.1016/0093-691x(86)90174-3
Squires, E L, et al. "Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares." Theriogenology vol. 26,5 (1986): 661-70. doi: https://doi.org/10.1016/0093-691x(86)90174-3
Squires EL, Garcia RH, Ginther OJ, Voss JL, Seidel GE. Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares. Theriogenology. 1986 Nov;26(5):661-70. doi: 10.1016/0093-691x(86)90174-3. PMID: 16726233.
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Theriogenology. 1986 Nov;26(5):661-70. doi: 10.1016/0093-691x(86)90174-3.

Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares.

Theriogenology

E L Squires, R H Garcia, O J Ginther, J L Voss, G E Seidel

Affiliations

  1. Animal Reproduction Laboratory Colorado State University Fort Collins, CO 80523 USA.

PMID: 16726233 DOI: 10.1016/0093-691x(86)90174-3

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 < 0.05) the number of follicles > 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 < 0.05) follicles 25 to 30 mm and > 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.

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