title: The use of steroid hormones in superovulation of Nelore donors at different stages of estrous cycle.
abstract: The objective of the present study was to evaluate the superovulatory response and ova/embryo recovery from Nelore donors following treatment with a controlled internal drug releasing device and estradiol benzoate (CIDR-B program) at different stages of the estrous cycle. The control group (TI; n=40) received a standard superovulation protocol with females of this group being between days 9 and 12 of the estrous cycle (estrus = day 0). The donors that received a CIDR-B program containing 1.9 g progesterone and an intramuscular injection of estradiol benzoate (2 mg) were at day 0 (TII; n=30), between days 2 and 6 (TIII; n=30), days 7 and 12 (TIV; n=30), days 13 and 16 (TV; n=30) and days 17 and 20 (TVI; n=30) of the estrous cycle. Superovulation was induced with 400 IU of p-FSH, divided into eight decreasing doses (80/80; 60/60; 40/40; 20/20) at intervals of 12h. The donors received PGF2alpha (Cloprostenol) 48 h after beginning the treatment and CIDRs were removed 12h later. Artificial inseminations (AI) were performed 12 and 22 h after the initiation of estrus and embryos were collected 7 days after AI. The mean numbers (+/-S.E.M.) of total ova and embryos, viable (transferable) and degenerated embryos were 14.2+/-11.3, 7.4+/-6.9 and 3.2+/-3.5 (TI), 13.3+/-10.4, 7.1+/-6.2 and 3.3+/-4.3 (TII), 13.5+/-7.0, 8.1+/-6.7 and 2.3+/-3.0 (TIII), 17.4+/-9.9, 9.4+/-6.9 and 4.0+/-4.4 (TIV), 16.9+/-8.8, 9.8+/-8.1 and 2.7+/-2.5 (TV) and 13.0+/-7.8, 7.2+/-6.9 and 2.3+/-2.5 (TVI), with no significant differences (P>/=0.05) among groups. Pregnancy rates of 67.1% (TI; n=86/128), 60.8% (TII; n=59/97), 62.5% (TIII; n=73/115), 64.1% (TIV; n=84/131), 72.3% (TV; n=81/112) and 60.6% (TVI; n=63/104) were obtained with embryos transferred from these collections and did not differ significantly (P>/=0.05) among groups. The results of the present study allow us to conclude that a combination of steroid hormones may be used prior to superovulation in Nelore donors, at any stage of the estrous cycle without affecting the efficiency of embryo transfer programs.
authors.affiliation: Programa de Pós-Graduação em Ciência Veterinária, UFRPE, Av. D. Manoel de Medeiros s/n, Dois Irmãos, CEP 52171-900 Recife-PE, Brazil.
authors.forename: J C O
authors.initials: JC
authors.lastname: Andrade
authors.forename: M A L
authors.initials: MA
authors.lastname: Oliveira
authors.forename: P F
authors.initials: PF
authors.lastname: Lima
authors.forename: S I
authors.initials: SI
authors.lastname: Guido
authors.forename: C C
authors.initials: CC
authors.lastname: Bartolomeu
authors.forename: F
authors.initials: F
authors.lastname: Tenório Filho
authors.forename: V M R
authors.initials: VM
authors.lastname: Pina
authors.forename: T C
authors.initials: TC
authors.lastname: Iunes-Souza
authors.forename: N R O
authors.initials: NR
authors.lastname: Paula
authors.forename: J C C
authors.initials: JC
authors.lastname: Freitas
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D002417:Cattle; D002452:Cell Count; D004624:Embryo Transfer / Q000662:veterinary; D004622:Embryo, Mammalian / Q000502:physiology; D004958:Estradiol / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D030762:Estrous Cycle; D005260:Female; D007273:Injections, Intramuscular; D007315:Insemination, Artificial / Q000662:veterinary; D010063:Ovum; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage*; D013480:Superovulation; D020858:Tissue and Organ Harvesting / Q000662:veterinary
chemical_list: C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol