title: Embryo Mortality Around the Period of Maintenance of the Corpus Luteum Causes Alterations to the Ovarian Function of Lactating Dairy Cows.
abstract: Objectives were to identify cows with embryo mortality (EM) around the period of corpus luteum maintenance by interferon tau (IFNT) and to characterize ovarian function in cows that underwent EM. Lactating Holstein cows received artificial insemination (AI) (Day = 0) with semen or extender only. From Day 14 to 42 transrectal ultrasonography was performed daily to monitor ovarian dynamics and uterine contents whereas blood was collected every 48 h to determine ISG15 and MX2 mRNA abundance in blood mononuclear cells (Day 14 to 22 only) and determination of hormone concentrations. Cows were classified in the following reproductive status groups: cyclic (inseminated with extender; n = 15), pregnant (embryo present on Day 42; n = 23), no embryo (n = 23), and EM (n = 14). EM was defined as the presence of an embryo based on interferon-stimulated genes (ISG) mRNA abundance and concentrations of pregnancy-specific protein B (PSPB) above specific cutoff points but no embryo visualized by ultrasonography. Within the EM group, early EM (up to Day 22) was when ISG fold changes were above specific cutoff points from Day 18 to 22 and PSPB below 0.7 ng/ml on and after Day 24, whereas late EM (after Day 22) was when PSPB was above 0.7 ng/ml on or after Day 24 regardless of ISG expression. This experiment provided evidence that the combination of ISG expression patterns and PSPB concentrations is a reasonable method to determine EM around the period of corpus luteum maintenance by IFNT because cows with evidence of EM had patterns of ISG expression more similar to pregnant than cyclic cows or cows with no embryo. Within the EM group, only cows with late EM had delayed luteal regression and longer interovulatory intervals. No major alterations in follicular function were observed after the onset of luteolysis. Our results suggest that embryo development needs to continue beyond 22 days after AI to effectively prevent luteolysis and extend the luteal phase.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York.
authors.forename: Robert
authors.initials: R
authors.lastname: Wijma
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York.
authors.forename: Matias L
authors.initials: ML
authors.lastname: Stangaferro
authors.affiliation: Department of Animal Science, Center for Reproductive Biology and Health, Huck Institutes of the Life Sciences, Pennsylvania State University, State College, Pennsylvania.
authors.forename: Manasi M
authors.initials: MM
authors.lastname: Kamat
authors.affiliation: Department of Animal Science, Center for Reproductive Biology and Health, Huck Institutes of the Life Sciences, Pennsylvania State University, State College, Pennsylvania.
authors.forename: Sreelakshmi
authors.initials: S
authors.lastname: Vasudevan
authors.affiliation: Department of Animal Science, Center for Reproductive Biology and Health, Huck Institutes of the Life Sciences, Pennsylvania State University, State College, Pennsylvania.
authors.forename: Troy L
authors.initials: TL
authors.lastname: Ott
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York jog25@cornell.edu.
authors.forename: Julio O
authors.initials: JO
authors.lastname: Giordano
mesh_terms: D000818:Animals; D002417:Cattle; D003338:Corpus Luteum / Q000000981:diagnostic imaging / Q000502:physiology*; D020964:Embryo Loss / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000662:veterinary*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary*; D007774:Lactation / Q000502:physiology; D003341:Luteolysis / Q000502:physiology; D010053:Ovary / Q000000981:diagnostic imaging / Q000502:physiology*; D011247:Pregnancy; D014463:Ultrasonography
keywords: dairy cow; embryo mortality; interferon-stimulated genes; ovarian function; pregnancy-specific protein B