Induction of twinning in Korean native cattle by transfer of nuclear transplanted embryos II. Nuclear transfer using donor embryos originated from ovum pick-up(OPU) and activated recipient cytoplasts

핵이식 기법을 이용한 한우 쌍태생산에 관한 연구 II. Ovum pick-uo(OPU) 유래 공여핵 및 활성화 유도 수핵난자의 핵이식

The efficiency of nuclear transfer using donor embryos originated from ovum pickup(OPU) and activated recipient cytoplasts were examined for induction of twinning in Korean native cattle(KNC). After aspiration of follicle by OPU, regardless of the vacuum applied, we obtained same result in proportions of recovered cumulus-oocyte complex (COCs) with compact cumulus. Under electric stimulation(1.0kV/cm DC for $40{\mu}s$), most of activated oocytes proceed to anaphase II/telophase II within 3h(84.7%). In the treatment of oocyte activation, the preactivation which was performed before fusion had significant effect on the developmental rates to morula/blastocyst stage(9.4 vs 4.0%). In embryo transfer of nuclear transferred embryos, we obtained 2 twins from KNC recipients and 1 twin from a Holstein recipient. Our results showed that it is possible to obtain twins using nuclear transfer technique in KNC.