Negative Impact of High Doses of Follicle-Stimulating Hormone During Superovulation on Ovulatory Follicle Function in Small Ovarian Reserve Dairy Heifers.

When women with small ovarian reserves are subjected to assisted reproductive technologies (ART), high doses of gonadotropins are linked to high oocyte and embryo wastage and low live birth rates. We hypothesized that excessive FSH doses during superovulation are detrimental to ovulatory follicle function in individuals with a small ovarian reserve. To test this hypothesis, heifers with small ovarian reserves were injected twice daily for four days beginning on Day 1 of the estrous cycle with 35 IU, 70 IU, 140 IU, or 210 IU doses of Folltropin-V (FSH). Each heifer (n = 8) was superovulated using a Williams Latin Square Design. During each superovulation regimen, three prostaglandin F2α injections were given at 12 h intervals starting at the 7th FSH injection to regress the newly formed corpus luteum (CL). Human chorionic gonadotropin (hCG) was injected 12 h after the last (8th) FSH injection to induce ovulation. Daily ultrasonography and blood sampling were used to determine number and size of follicles and CL, uterine thickness, and circulating concentrations of estradiol, progesterone, and anti-Mullerian hormone (AMH). The highest doses of FSH did not increase AMH, progesterone, ovulatory-size follicle number, uterine thickness, or number of CL. However, estradiol production and ovulation rate were lower for heifers given high FSH doses compared to lower doses, indicating detrimental effects on ovulatory follicle function.