Pregnancy Rate of In Vitro Produced Korean Cattle Embryos according to Transport Time Course

This study was to investigate pregnancy rate of IVM/IVF/IVC Korean cattle (registered in government) embryos according to transport time course. For the production of embryos, oocytes recovered from slaughtered excellent grade cow and highly motile frozen-thawed bull semen (purchased from LIMC, KPN#497) was used. In vitro produced embryos were cultured in CR1aa medium for 8 days and some of them were frozen. The rate of average cleavage (>2-cell) was 83.0% (308/371) and blastocyst rate at day 8 was 34.7% (107/308). Among in vitro produced blastocyst embryos at day 8, most healthy embryos were freshly transferred on production day and some frozen embryos were direct transferred on appropriate day. These embryos were produced in a laboratory, embryo transfer (ET) was planned in 10 areas of the remote island (Jeju) from the laboratory by airplane. Thus, we examined the pregnancy rate in recipient cow according to embryo of transport time course before ET. From embryo transferred 44 recipient cows, overall pregnancy was 40.9% (18/44), these 18 cows were all calved [single, 94% (17/18); twin, 6% (1/18)] and total embryo implantation rate was 26% (19/66). Comparing transport time in the base of 6 hr, pregnancy rate in ET group required less 4 hr (60%, 9/15) was significantly higher than that required more 6 hr (26.3%, 5/19). In direct ET of freezing embryos, the pregnancy rate was 40% (4/10). However, it was difficult to find the meaning of temperature, pH and corpus luteum quality of recipients on comparison of pregnancy rate. When the cell death level of embryos according to storage time in thermos (straw container) before ET was measured by TUNEL staining, apoptotic index was increased with storage time-dependent. These results demonstrated that long distance transfer of IVM/IVF/IVC embryos is possible and the time of embryo transport is very important for the pregnancy rate on field trial.