|NORTHROP, E - South Dakota State University|
|AMUNDSON, OLIVIA - South Dakota State University|
|RICHARDSON, B - South Dakota State University|
|Cushman, Robert - Bob|
|PERRY, GEORGE - South Dakota State University|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2015
Publication Date: 7/1/2015
Citation: Northrop, E.J., Amundson, O.L., Richardson, B.N., McNeel, A.K., Cushman, R.A., Perry, G.A. 2015. Influence of estrus expression prior to fixed-time AI on embryo survival to maternal recognition of pregnancy [abstract]. Journal of Animal Science. 93 (Supplement s3):232.
Technical Abstract: Estradiol has been reported to play a critical role in pregnancy establishment and embryonic survival. Our objective was to focus on the role of preovulatory estradiol in embryo survival from fertilization to maternal recognition of pregnancy. Beef cows (n = 29) were synchronized with the CO-Synch protocol and AIed (d 0). Blood was collected to determine estradiol (d -2 to 0) and progesterone (d 0 to 16) concentrations. Cows were then divided into 2 groups based on expression of estrus (estrus and no estrus). On d 16 uteri were flushed to collect embryos. Total cellular RNA was extracted from blood leukocytes (d 16) to measure the expression of interferon-stimulated genes (ISG): ISG-15, OAS-1, and MX2. Flush media was also analyzed for protein and glucose concentrations. There was an effect of estrus, time, and estrus by time (P < 0.01) on circulating concentrations of estradiol, but there was no effect of estrus (P = 0.85) or estrus by time (P = 0.26) on circulating concentrations of progesterone. There was no difference in embryo recovery rate (P = 0.97; 45% vs 44%). When corrected for volume of flush media, there was no differences between estrus and no estrus for uterine flush protein (P = 0.51; 218 ± 94 vs 124 ± 104 mg/mL); or glucose (1960 ± 274 vs 2003 ± 304 mg/dL) content between estrus and no estrus. There was no difference (P > 0.20) in d 16 expression of ISG-15, OAS-1, or MX2 between estrus and no estrus animals, nor a difference between cows an embryo was or was not recovered from. However, there was a tendency for cows in which an embryo was recovered from to have greater concentrations of protein (P = 0.056; 314 ± 104 mg/dL) and glucose (P = 0.09; 2347 ± 303 mg/dL) in uterine flushes compared to cows in which an embryo was not recovered (28 ± 94 mg/mL and 1616 ± 274 mg/dL). In summary, there were no differences between cows that did or did not express estrus in ISG expression, or in protein or glucose concentration of uterine flushes. Therefore, the increased embryo survival to d 30 of gestation among cows that express estrus is not associated with embryo survival until maternal recognition.