title: Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer.
abstract: The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus x Bos taurus indicus) nonlactating cows and heifers (n=259) were treated with the following protocol: 2mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F(2alpha) (PGF(2alpha)) and CIDR withdrawal (Day 8); and 1mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n=90) or in vitro-produced (n=87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P<0.001). Mean (+/-SD) plasma progesterone (P(4)) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2+/-5.0 vs. 3.8+/-2.4 ng/mL; P=0.02). Mean pixel values (71.8+/-1.3 vs. 71.2+/-1.1) and pixel heterogeneity (14.8+/-0.3 vs. 14.5+/-0.5) were similar between pregnant and nonpregnant recipients (P>0.10). No significant relationship was detected between pregnancy outcome and plasma P(4), corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.
authors.affiliation: Federal University of Viçosa, Av. P.H. Rolfs s/n, Viçosa, Minas Gerais, Brazil. lgbsiqueira@yahoo.com.br
authors.forename: L G B
authors.initials: LG
authors.lastname: Siqueira
authors.forename: C A A
authors.initials: CA
authors.lastname: Torres
authors.forename: E D
authors.initials: ED
authors.lastname: Souza
authors.forename: P L J
authors.initials: PL
authors.lastname: Monteiro
authors.forename: E K N
authors.initials: EK
authors.lastname: Arashiro
authors.forename: L S A
authors.initials: LS
authors.lastname: Camargo
authors.forename: C A C
authors.initials: CA
authors.lastname: Fernandes
authors.forename: J H M
authors.initials: JH
authors.lastname: Viana
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D002417:Cattle / Q000502:physiology*; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D003338:Corpus Luteum / Q000033:anatomy & histology / Q000502:physiology*; D015237:Dinoprost / Q000008:administration & dosage; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary*; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D010053:Ovary / Q000000981:diagnostic imaging; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood; D013480:Superovulation; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D006063:Chorionic Gonadotropin; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost