The present invention provides a method for producing cloned cows by employing in vitro maturation of oocytes and nuclear transfer techniques. The method comprises collecting donor somatic cell lines from cows; maturing oocytes extracted from an ovary in vitro; enucleating the oocyte by cutting a portion of the zona pellucida and squeezing out a portion of the cytoplasm, including the first polar body; inserting the donor somatic cell into the oocyte; electrofusing the cells to produce embryos; post-activating the embryos; transferring them into surrogate cows to produce cloned calves.
