Role of preovulatory concentrations of estradiol on timing of conception and regulation of the uterine environment in beef cattle.

Role of preovulatory concentrations of estradiol on timing of conception and regulation of the uterine environment in beef cattle. Syst Biol Reprod Med. 2019 Dec 07;:1-14 Authors: Perry GA, Cushman RA, Perry BL, Schiefelbein AK, Northrop EJ, Rich JJJ, Perkins SD Abstract The ability to induce ovulation with an injection of GnRH facilitated the development of fixed-time artificial insemination (AI) protocols. However, animals that exhibit estrus prior to fixed-time AI have greater pregnancy success. Thus, the objectives of the present experiments were to determine the impact of estrus expression prior to fixed-time AI on timing of conception and to characterize the role of preovulatory estradiol in regulating changes in expression of uterine genes. In experiment 1, data were collected from 4,499 beef cows inseminated by fixed-time AI in 31 different herds. Animals that did not conceive to AI but exhibited estrus before timed-AI were more likely to conceive during cycle 1 after AI, and overall conceived earlier in the breeding season compared to animals that did not exhibit estrus. In experiment 2, beef cows were synchronized using a fixed-time AI protocol. Uterine horn biopsies and blood samples were collected on Day 0, 5, 10, or 16. Concentrations of estradiol on Day 0 did not influence expression of progesterone receptor, ER beta, or oxytocin receptor. Increased concentrations of estradiol on Day 0 increased expression of ER alpha f...
Source: Systems Biology in Reproductive Medicine - Category: Reproduction Medicine Authors: Tags: Syst Biol Reprod Med Source Type: research