title: Comparison of embryo yield and pregnancy rate between in vivo and in vitro methods in the same Nelore (Bos indicus) donor cows.
abstract: To investigate why the preferred means to produce bovine embryos in Brazil has changed from in vivo to in vitro, we compared these two approaches in the same Nelore cows (n=30) and assessed total embryo production and pregnancy rates. Without a specific schedule, all cows were subjected to ultrasound-guided ovum pick up (OPU)/in vitro production (IVP) and MOET, with intervals ranging from 15 to 45 d between procedures, respectively. To produce in vivo embryos, cows were superovulated and embryos were recovered nonsurgically from 1 to 3 times (1.4+/-0.6), whereas OPU/IVP was repeated from 1 to 5 times (3.2+/-1.2) in each donor cow during a 12-mo interval. Embryos obtained from both methods were transferred to crossbred heifers. On average, 25.6+/-15.3 immature oocytes were collected per OPU attempt. The average number of embryos produced by OPU/IVP (9.4+/-5.3) was higher (P<0.05) than the MOET method (6.7+/-3.7). However, pregnancy rates were lower (P<0.05) following transfer of IVP (33.5%) versus in vivo-derived embryos (41.5%) embryos. Embryonic losses between Days 30 and 60 and fetal sex ratio were similar (P>0.05) between in vivo and in vitro-derived embryos. We concluded that in Nelore cows, with an interval of 15 d between OPU procedures, it was possible to produce more embryos and pregnancies compared to conventional MOET.
authors.affiliation: In vitro Brasil Ltda. Mogi Mirim SP, 13800-970 Brazil.
authors.forename: J H F
authors.initials: JH
authors.lastname: Pontes
authors.forename: I
authors.initials: I
authors.lastname: Nonato-Junior
authors.forename: B V
authors.initials: BV
authors.lastname: Sanches
authors.forename: J C
authors.initials: JC
authors.lastname: Ereno-Junior
authors.forename: S
authors.initials: S
authors.lastname: Uvo
authors.forename: T R R
authors.initials: TR
authors.lastname: Barreiros
authors.forename: J A
authors.initials: JA
authors.lastname: Oliveira
authors.forename: J F
authors.initials: JF
authors.lastname: Hasler
authors.forename: M M
authors.initials: MM
authors.lastname: Seneda
mesh_terms: D000818:Animals; D002417:Cattle; D004624:Embryo Transfer / Q000662:veterinary*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D011247:Pregnancy; D018873:Pregnancy Rate; D013480:Superovulation