title: Effect of estradiol cypionate and GnRH treatment on plasma estradiol-17β concentrations, synchronization of ovulation and on pregnancy rates in suckled beef cows treated with FTAI-based protocols.
abstract: Two experiments were conducted to evaluate the effect of different ovulation inducers on E-17β plasma concentrations, synchronized ovulations and pregnancy rates. In Experiment 1, cows received a progesterone intravaginal device (PID) with 1 g of progesterone (P4) plus 2 mg of estradiol benzoate (EB) (day 0). At PID removal (day 8), cows received 0.150 mg of D-cloprostenol and were randomly assigned to four treatment groups (n = 10/treatment): Group ECP: 1 mg of estradiol cypionate at PID removal, Group EB: 1 mg of EB 24 hr after PID removal, Group GnRH: 10 μg of GnRH 48 hr after PID removal, Group ECP-GnRH: 1 mg of ECP at PID removal plus 10 μg of GnRH 48 hr later. Ultrasonographic examinations were performed to detect the dominant follicle and ovulation. GnRH-treated cows ovulated later (p < .05) compared to ECP- and ECP+GnRH-treated cows. There were effects of treatment, time and their interaction on E-17β concentrations (p < .05). ECP treatment affected plasma E-17β concentration, which increased earlier and decreased later compared to treatments without ECP. In Experiment 2, cows received (i) ECP: n = 126; (ii) EB: n = 126; (iii) GnRH: n = 136; (iv) ECP+GnRH: n = 139; FTAI was performed 48-50 hr after PID removal. Pregnancy rates did not differ among ovulation inducers (p > .05; ECP: 54.0%, 68/126; EB: 49.2%, 62/126; GnRH: 40.4%, 55/136; ECP+GnRH: 43.9%, 61/139). In conclusion, ECP administration (ECP and ECP+GnRH treatments) affected E-17β concentrations, determining its earlier increase and later decrease compared to treatments without ECP (EB and GnRH treatments). ECP+GnRH-treated cows achieved the best distribution of ovulations without affecting pregnancy rates.
authors.affiliation: CONICET fellowship (CIVETAN), Campus Universitario, Tandil, Buenos Aires, Argentina. uslenghi@vet.unicen.edu.ar.|Área de Reproducción, Centro de Investigación Veterinaria de Tandil, (CIVETAN, CONICET-CICPBA), FISFARVET, Fac. de Cs. Veterinarias, U.N.C.P.B.A, Tandil, Buenos Aires, Argentina. uslenghi@vet.unicen.edu.ar.
authors.forename: G
authors.initials: G
authors.lastname: Uslenghi
authors.affiliation: Private practice, Buenos Aires, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Vater
authors.affiliation: Private practice, Buenos Aires, Argentina.
authors.forename: S
authors.initials: S
authors.lastname: Rodríguez Aguilar
authors.affiliation: Área de Reproducción, Centro de Investigación Veterinaria de Tandil, (CIVETAN, CONICET-CICPBA), FISFARVET, Fac. de Cs. Veterinarias, U.N.C.P.B.A, Tandil, Buenos Aires, Argentina.
authors.forename: J
authors.initials: J
authors.lastname: Cabodevila
authors.affiliation: Área de Reproducción, Centro de Investigación Veterinaria de Tandil, (CIVETAN, CONICET-CICPBA), FISFARVET, Fac. de Cs. Veterinarias, U.N.C.P.B.A, Tandil, Buenos Aires, Argentina.
authors.forename: S
authors.initials: S
authors.lastname: Callejas
mesh_terms: D000818:Animals; D002417:Cattle; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000494:pharmacology; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007774:Lactation; D010060:Ovulation / Q000187:drug effects*; D011247:Pregnancy; D018873:Pregnancy Rate
chemical_list: D003271:Contraceptive Agents, Female; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol