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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #373222
Research Project: Improving Livestock Production by Developing Reproductive and Precision Management Technologies

Location: Livestock Bio-Systems

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

Author
item PERRY, GEORGE - South Dakota State University
item Cushman, Robert - Bob
item PERRY, BRANDI - South Dakota State University
item SCHIEFELBEIN, AMANDA - South Dakota State University
item NORTHROP, EMMALEE - South Dakota State University
item RICH, JERICA - South Dakota State University
item PERKINS, STEPHANIE - South Dakota State University

Submitted to: Systems Biology in Reproductive Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2019
Publication Date: 12/7/2019
Citation: Perry, G.A., Cushman, R.A., Perry, B.L., Schiefelbein, A.K., Northrop, E.J., Rich, J.J., Perkins, S.D. 2019. Role of preovulatory concentrations of estradiol on timing of conception and regulation of the uterine environment in beef cattle. Systems Biology in Reproductive Medicine. 66(1):12-25. https://doi.org/10.1080/19396368.2019.1695979.
DOI: https://doi.org/10.1080/19396368.2019.1695979

Interpretive Summary: Estradiol from the ovary plays a critical role in uterine function and recognition of pregnancy. In the present study, we investigated how estradiol influences timing of conception and recognition of pregnancy in beef cows. Cows that did not respond properly to a hormonal synchronization protocol and had low circulating concentrations of estradiol were less likely to have a normal estrous cycle and conceived very late in the breeding season or were not pregnant. Biochemical analysis of uterine tissues demonstrated that the biological clock was disrupted in the uterus of heifers that had low circulating concentrations of estradiol. To improve fertility in beef cows, management strategies that maximize estradiol production by the ovary at the start of the breeding season should be investigated.

Technical 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 from Days 0 to 5 of the estrous cycle. Furthermore, cows with increased concentrations of estradiol on Day 0 had increased expression of inhibin beta A, and uterine milk protein precursor. Thus, animals that do not exhibit estrus prior to fixed-time AI had decreased breeding season pregnancy success and conceived later in the breeding season, and preovulatory concentrations of estradiol likely play a major role in this establishment of pregnancy, not only directly by regulating uterine gene expression, but also indirectly throughout the subsequent estrous cycle.