The Impact of Preovulatory Estradiol on the Oviductal and Uterine Environments, and Profit per Pregnancy Associated with the Detection of Estrus

The expression of estrus and preovulatory estradiol concentrations influence pregnancy success in beef cattle; however, it is not clear how estrus and/or estradiol impact oviductal and uterine environments. The goals of this dissertation were to evaluate how preovulatory estradiol impacts oviductal gene and protein expression, how physiological estradiol exposure with/without estrus impacts pregnancy-associated factors, and how utilizing the detection of estrus with timed-artificial insemination (TAI) impacts expense and profit per pregnancy. In Chapter II, oviducts (n=6) were collected from synchronized beef cows with High (10.12±0.62 pg/ml, n=3) or Low (5.97±0.62 pg/ml, n=3) estradiol concentrations at fixed-time artificial insemination (FTAI), and differentially expressed genes were identified. Oviductal gene expression was hormonally regulated, with differential gene expression between High and Low cows. In Chapter III, oviducts and ovaries were collected from synchronized beef cows with High (≥6.0 pg/mL; n=4) or Low (≤4.5 pg/mL; n=5) estradiol concentrations. Oviducts were fixed and embedded for localization of prostaglandin E2 synthase (PTGES) and prostaglandin E2 receptor 2 (PTGER2) localization by immunofluorescence. There was no difference in immunoreactivity of PTGER2 protein; however, immunoreactivity of PTGES protein tended to be more intense in oviducts from High compared with Low cows. In Chapter IV, beef cows (n=603) were synchronized and grouped based on estrus by FTAI (day 0), or the administration of gonadotropin-releasing hormone (GnRH) and/or exogenous estradiol, and estrus by day 7. While estrus or physiological estradiol did not impact pregnancy or interferon-stimulated gene expression by day 19, pregnancy rate and pregnancy-associated glycoprotein abundance by day 24 differed between cows that did or did not express estrus by day 7. Differences in day 55 and 90 pregnancy were observed due to estrus by day 7, but not due to estradiol exposure without estrus. In Chapter V, beef cows and heifers were synchronized using a TAI protocol with (6d; n=437) or without (7d; n=429) estrus detection. Pregnancy rates did not differ; however, decreased expense and increased profit per pregnancy were observed with the 6d compared with the 7d protocol. These data indicate estrus supports pregnancy through maternal environment changes, and utilizing detection of estrus with TAI is more economical.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physiology of Reproduction

Grantor

Texas A&M University

Year dc:date.issued

2024

Author dc:creator

• Quail, Lacey Kay

Advisor dc:contributor.advisor

• Perry, George

Committee members dc:contributor.committeemember

• Cushman, Robert
• Geary, Thomas
• Anderson, David

• Biology, Animal Physiology
• Economics, Agricultural

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/1588963

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F1588963