The present invention provides data to demonstrate that the re-fusion, of a mammalian karyoplast to an enucleated in vivo ovulated oocyte, following an unsuccessful initial simultaneous electrical fusion and activation event offers an additional alternative and improvement in the creation of activated and fused nuclear transfer-capable embryos for the production of live offspring in various mammalian non-human species including goats, pigs, rodents, primates, rabbits and cattle. Additionally, multiple electrical pulses offers an alternative and more efficient activation method in a simultaneous fusion and activation methodology for viable offspring production in a animal nuclear transfer program.