Coculture of bovine demiembryos prior to freezing.

Pregnancy rates after transfer of frozen/thawed bisected embryos, demiembryos, have until now been very low. In the present study it was attempted to improve the freezability rate of demiembryos by culturing them on a monolayer of bovine oviduct epithelial cells (BOEC) prior to freezing. The cultured frozen/thawed demiembryos showed a lower developmental rate than intact embryos. The pregnancy rate (23%) following transfer was not different from the pregnancy rate after transfer of unfrozen demiembryos (26%). The calving rate (4%), however, was significantly lower than the calving rate after transfer of fresh demiembryos (23%). Although the overall pregnancy rate achieved in this study was low, it can be concluded that a co-culture period upon BOEC prior to freezing does not improve the viability of frozen demiembryos.