title: Effect of temporary meiosis block during prematuration of bovine cumulus-oocyte complexes on pregnancy rates in a commercial setting for in vitro embryo production.
abstract: Ovum pick up (OPU) associated with in vitro production (IVP) of embryos has been shown as an important tool in cattle breeding to increase the number of descendants from animals of high genetic value. In herds maintained distant from the laboratory, collecting cumulus-oocyte complexes (COCs) and transporting them to the laboratory may take several hours and decrease COCs viability, representing a challenge for commercial settings. In this study, a prematuration culture to induce temporary meiosis block was evaluated in a commercial scale IVP setting as a strategy to transport bovine OPU-derived COCs from Nelore and Brangus donors. Effects on embryo yield and pregnancy rates were assessed. Viable COCs from each donor were destined to one of the experimental groups (control, blocks 1 and 2). Control group COCs were placed in cryotubes with 1 mL TCM199-HEPES. In block groups (1 and 2), COCs were placed in cryotubes with 300 μL TCM 199 + 12 μM butyrolactone I (block medium). All groups were gassed and kept in a thermos bottle for 4 hours at 36 °C. Next, COCs in the control group were transferred to IVM medium and block 1 group to block medium, and cultured for 22 hours and 15 hours, respectively, at 38.5 °C and 5% CO2 in air. Block 2 COCs were kept in the cryotubes and in the thermos bottle for another 15 hours at 36 °C to simulate long-term transport conditions. After meiosis block in prematuration culture, blocks 1 and 2 COCs were matured in vitro for 22 hours as for the control group. After IVM, COCs in all groups were submitted to IVF and IVC, and blastocyst rates were evaluated on day 7. Embryos were transferred and pregnancy rates evaluated at 60 days of gestation. The mean total number of COCs retrieved by OPU did not differ between Nelore and Brangus donors (16.8 and 17.2, respectively, P > 0.05), but Nelore donors produced more viable COCs than Brangus (10.1 and 7.6, respectively, P < 0.05) and more embryos/cow (3.8 and 2.7, respectively, P < 0.05). Blastocyst rates were similar for control (40.2% and 36.7%), block 1 (37.3% and 34.5%), and block 2 groups (34.7% and 33.6%) for Nelore and Brangus cattle, respectively (P > 0.05). Pregnancy rates did not differ regardless of breed or treatment (36.7%, P > 0.05). In conclusion, temporary meiosis block during prematuration culture did not affect embryo development or pregnancy rates; therefore, this strategy may be used to transport bovine COCs in a commercial IVP setting.
authors.affiliation: Central Avançada de Biotecnologia da Reprodução Animal (CENABRA), Agropecuária Laffranchi, Tamarana, Paraná, Brazil; Escola de Medicina Veterinária, Universidade Norte do Paraná, Arapongas, Paraná, Brazil.
authors.forename: Samuel
authors.initials: S
authors.lastname: Guemra
authors.affiliation: Central Avançada de Biotecnologia da Reprodução Animal (CENABRA), Agropecuária Laffranchi, Tamarana, Paraná, Brazil.
authors.forename: Eriko
authors.initials: E
authors.lastname: da Silva Santo
authors.affiliation: Central Avançada de Biotecnologia da Reprodução Animal (CENABRA), Agropecuária Laffranchi, Tamarana, Paraná, Brazil.
authors.forename: Renato
authors.initials: R
authors.lastname: Zanin
authors.affiliation: Central Avançada de Biotecnologia da Reprodução Animal (CENABRA), Agropecuária Laffranchi, Tamarana, Paraná, Brazil; Escola de Medicina Veterinária, Universidade Norte do Paraná, Arapongas, Paraná, Brazil.
authors.forename: Paulo Sergio
authors.initials: PS
authors.lastname: Monzani
authors.affiliation: Escola de Medicina Veterinária, Universidade Norte do Paraná, Arapongas, Paraná, Brazil.
authors.forename: Tobias Canan
authors.initials: TC
authors.lastname: Sovernigo
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Otávio Mitio
authors.initials: OM
authors.lastname: Ohashi
authors.affiliation: Departamento de Ciências Básicas, Universidade de São Paulo, Pirassununga, São Paulo, Brazil.
authors.forename: Cláudia Lima
authors.initials: CL
authors.lastname: Verde Leal
authors.affiliation: Central Avançada de Biotecnologia da Reprodução Animal (CENABRA), Agropecuária Laffranchi, Tamarana, Paraná, Brazil; Escola de Medicina Veterinária, Universidade Norte do Paraná, Arapongas, Paraná, Brazil. Electronic address: paulo_adona@yahoo.com.br.
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Adona
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D054885:Cumulus Cells / Q000502:physiology*; D046149:Embryo Culture Techniques / Q000662:veterinary; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D059471:In Vitro Oocyte Maturation Techniques; D008540:Meiosis / Q000502:physiology*; D009865:Oocytes / Q000502:physiology*; D011247:Pregnancy; D018873:Pregnancy Rate
keywords: Butyrolactone I; Maturation; Ovum pick up and oocytes; Transport