|Northrop, Emmalee - South Dakota State University|
|Rich, Jerica - South Dakota State University|
|Cushman, Robert - Bob|
|Mcneel, Anthony - Former ARS Employee|
|Soares, Emerson - Universidade Federal De Santa Maria|
|Brooks, Kelsey - University Of Missouri|
|Spencer, Thomas - University Of Missouri|
|Perry, George - University Of Missouri|
Submitted to: Biology of Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2018
Publication Date: 9/1/2018
Citation: Northrop, E.J., Rich, J.J., Cushman, R.A., McNeel, A.K., Soares, E.M., Brooks, K., Spencer, T.E., Perry, G.A. 2018. Effects of preovulatory estradiol on uterine environment and conceptus survival from fertilization to maternal recognition of pregnancy. Biology of Reproduction. 99(3):629-638. https://doi.org/10.1093/biolre/ioy086.
DOI: https://doi.org/10.1093/biolre/ioy086 Interpretive Summary: Early embryonic mortality is believed to be a risk factor for pregnancy failure in beef cows. Estradiol concentrations at the time of insemination impact embryonic survival, because cows with elevated concentrations of estradiol have improved fertility. To determine if this improved fertility was due to increased embryonic survival, we collected conceptuses on day 16 after insemination in beef cows differing in estradiol concentrations at insemination. There was no difference in conceptus survival to day 16 among beef cows with and without elevated preovulatory estradiol concentrations. From these results, we conclude that differences in failure to maintain pregnancy occur after day 16 of pregnancy in cows without elevated estradiol concentrations at insemination.
Technical Abstract: Preovulatory estradiol is known to impact embryo quality and survival. The objective of this study was to determine the effects of preovulatory estradiol on the uterine environment and conceptus survival through maternal recognition of pregnancy. Beef cows/heifers were AIed following induced ovulation. Cows were grouped into high and low preovulatory estradiol. Conceptuses were collected on day 16 nonsurgically (Rep 1; n = 20), or following slaughter (Rep 2; n = 29). Blood was collected to determine plasma glucose concentrations, and uterine luminal 'uid (ULF) was analyzed for protein, glucose, and interferon tau (IFNT) concentrations. Total cellular RNA was extracted from caruncular (CAR) and intercaruncular (INCAR) endometrial tissue. There was no effect of preovulatory estradiol on conceptus recovery rate (P = 0.38) or on apoptosis rate in the trophectoderm (P = 0.64). Cows in which a conceptus was recovered had greater concentrations of protein in the ULF (P = 0.04). Animals with elevated preovulatory estradiol had greater endometrial abundance of SLC2A1 (P = 0.05) and SLC5A1 (P = 0.04) in both INCAR and CAR tissue. Presence of a conceptus also tended to increase (P = 0.10) abundance of SLC5A1 in INCAR. In CAR tissue, cows with a conceptus had decreased SLC2A4 abundance (P = 0.05). In summary, conceptus recovery rates, apoptosis in the trophectoderm, IFNT, glucose, and protein concentration in ULF did not differ between cows that did or did not have an increase in preovulatory estradiol concentrations. Thus, there is no indication of increased conceptus survival to day 16 of pregnancy based on estradiol concentrations.