Guemra S.,Central Avancada de Biotecnologia da Reproducao Animal CENABRA |
Guemra S.,University of Northern Parana |
da Silva Santo E.,Central Avancada de Biotecnologia da Reproducao Animal CENABRA |
Zanin R.,Central Avancada de Biotecnologia da Reproducao Animal CENABRA |
And 7 more authors.
Theriogenology | Year: 2014
Ovum pick up (OPU) associated with invitro 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 1mL TCM199-HEPES. In block groups (1and 2), COCs were placed in cryotubes with 300μL TCM 199 + 12μM butyrolactone I (block medium). All groups were gassed and kept in a thermos bottle for 4hours at 36 °C. Next, COCs in the control group were transferred to IVM medium and block 1 group to block medium, and cultured for 22hours and 15hours, 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 15hours at 36°C to simulate long-term transport conditions. After meiosis block in prematuration culture, blocks 1 and 2 COCs were matured invitro for 22hours 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 60days 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. © 2014 Elsevier Inc. Source