Effect of fetal calf serum on production and crytolerance of in vitro bovine embryos from ecuadorian creole heifers

In the Ecuadorian Andes there is a Creole bovine biotype whose population is disappearing. In vitro embryo production and cryopreservation is an important biotechnology that allows the conservation of animals threatened with extinction. The objective of this study was to determine the in vitro production and cryopreservation of embryos from creole heifers raised in the highlands of Ecuador. Immature cumulus-oocyte complexes (COC´s) were retrieved by ovum pickup from 10 Creole heifers (OPU) and from abattoir ovaries (control). The experiment was completed within 8 replicates. COC´s were cultured in a maturation medium following IVF and in vitro culture. After denudation (Day 1 after IVF), presumptive embryos from each oocyte source were split into 2 groups: with (FCS+) and without (FCS-) FCS (2,5%), which was added on day 5 after IVF. On day 7, embryos were evaluated, and those with quality I were vitrified. After warming embryo re-expansion at 2h and embryo re-expansion and hatching at 24 and 48h were evaluated. Regardless of the oocyte source, the addition of 2,5% FCS decreased embryo re-expansion at 2h and reduced embryo hatching at 48h in the OPU group. In conclusion, FCS did not improve embryo production and adversely affected the cryotolerance of embryos produced in vitro from Ecuadorian creole heifers.