title: Temporarily decreasing progesterone after timed artificial insemination decreased expression of interferon-tau stimulated gene 15 (ISG15) in blood leukocytes, serum pregnancy-specific protein B concentrations, and embryo size in lactating Holstein cows.
abstract: Our objective was to evaluate the effects of temporarily decreasing progesterone (P4) after timed artificial insemination (TAI) on embryonic growth in dairy cows. Lactating Holstein cows (n = 80) were submitted to a Double-Ovsynch protocol for first TAI and were assigned randomly to receive 12.5 mg of PGF2α5 d after the last GnRH treatment (LowP4) or remain untreated (control). Blood samples were collected thrice weekly from 5 to 29 d after TAI for all cows and from 32 to 67 d for pregnant cows, and were analyzed for P4 and pregnancy-specific protein B concentrations. Expression of interferon-tau stimulated gene 15 (ISG15) was assessed in blood leukocyte mRNA 18 and 20 d after TAI. Pregnancy diagnosis was performed weekly using ultrasound from 32 to 67 d after TAI, and embryonic crown-rump length was measured 32, 39, and 46 d after TAI. Data were analyzed by ANOVA and logistic regression using the MIXED and GLIMMIX procedures of SAS. The LowP4 cows had less P4 than control cows from 6 to 11 d after TAI; however, pregnancy outcomes 32 d after TAI and pregnancy loss from 32 to 67 d after TAI did not differ between treatments. Control cows diagnosed pregnant 32 d after TAI had greater expression of ISG15 20 d after TAI than LowP4 cows diagnosed pregnant 32 d after TAI, and pregnant control cows had greater pregnancy-specific protein B concentrations from 25 to 67 d after TAI than pregnant LowP4 cows. Embryo size did not differ between treatments 32 and 39 d after TAI, but control cows had larger embryos 46 d after TAI. In conclusion, temporarily decreasing P4 after TAI decreased embryonic growth during early pregnancy in lactating Holstein cows but did not affect pregnancies per artificial insemination or pregnancy loss.
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: P D
authors.initials: PD
authors.lastname: Carvalho
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: C C
authors.initials: CC
authors.lastname: Consentini
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: S R
authors.initials: SR
authors.lastname: Weaver
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: R V
authors.initials: RV
authors.lastname: Barleta
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: L L
authors.initials: LL
authors.lastname: Hernandez
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706. Electronic address: pmfricke@wisc.edu.
authors.forename: P M
authors.initials: PM
authors.lastname: Fricke
mesh_terms: D000034:Abortion, Veterinary; D000818:Animals; D002417:Cattle; D015237:Dinoprost / Q000494:pharmacology; D004973:Estrus Synchronization; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007315:Insemination, Artificial / Q000662:veterinary; D007774:Lactation / Q000187:drug effects; D007962:Leukocytes; D011247:Pregnancy; D011374:Progesterone / Q000097:blood*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D015237:Dinoprost
keywords: embryo size; interferon-tau stimulated gene 15; pregnancy-specific protein B; progesterone