In vitro maturation and fertilization of ovine oocytes in a system with absence of 5% C02

Abstract

In vitro maturation and fertilization or ovine oocytes in system with absence or C02 was studied. The cumulus oocyte complexes (COCs) were matured in four different maturation medium, namely:a). TCM-199 only, b).TCM-199 +10 mM Hepes, c). TCM-199 + 20 mM Hepes and d). TCM-199 + 30mM Hepes. The COCs were incubated in the incubator with 5% CO2, incubator without 5% C02 and incubator with effervescent granule (EG) as the source of 5% C02 at38.50C for 24 hours. Four different time of incubation (20, 24,28 and 32 hours) in system without 5% CO2 was design to get the maturation rate. Treatments above were used to mature the oocytes for in vitro fertilization. The treatment of fertilization consists of the COCs fertilized for 18 hours In three incubator systems. The maturation rates of COCs in the incubator without 5% C02 or EG gradually increased by increasing of Hepes level from 0 mM to 20 mM, whereas the maturation rates in the incubator with 5% C0 was decreased by increasing Hepes level in medium.However, they were not significantly different among the treatments, but there was the interaction between using of Hepes and incubator system. The level of 0 mM Hepes in the incubator without 5% C0 and 30 mM Hepes in the incubator with 5% C01had the lowest maturation rate. The optimal maturation rate was obtained when COCs were incubated for more than 28 hours. The fertilization rate was not affected by incubator system. These results concluded that in vitro maturation and fertilization of ovine oocytes could be done in the incubator without 5% col by adding the 10-20 mM Hepes buffered into TCM-199 medium.