Production of Calves Derived from Embryos Produced by In Vitro Matured, Fertilized and Cultured Oocytes Recovered from Individual Cows

The objective of this study was to improve culture condition of in vitro produced bovine embryo cultured in CR1aa and to examine the developmental ability of the oocytes from a small number of oocytes per drop culture to blastocyst stage in vitro. Bovine cumulus-oocytes complexes (COCs) were matured, fertilized in a 100 μl-drop (10 presumptive COCs/drop) of medium. After insemination, zygotes were divided into three groups; (1) CR1aa: zygotes were cultured in 100 μl-drop of CR1aa (2) CR1aa+TCM: at 72 h after culture in CR1aa, embryos were cultured in TCM (3) TCM: zygotes were cultured in TCM. The blastocyst production rate was significantly higher (p<0.05, P<0.01) with CR1aa+TCM (42.4%) than those of CR1aa+CR1aa and TCM+TCM (31.3, 22.5%, respectively). To examine the effect of number of oocytes on the IVMFC, zygotes were cultured 2-9 or 10 embryos per 100 μl drop in CR1aa+TCM for 11 days. The proportion of embryos cleaved and blastocysts were not different between embryos derived from 10 embryos/drop and 2-9 embryos/drop (80.9% vs. 13.6% and 65.5% vs. 13.7%, respectively). Four blastocysts developed from 2-9 embryos per drop were transferred into recipients. One of the 4 recipients became pregnant. One male live calf was born at 286 day. These results indicate that CR1aa+TCM are effective media for IVC of a small number of embryos per drop, and embryos from a small number of embryos per drop have the developmental capacity to become calf.