Application study of developmental engineering for livestock production.

This paper describes several technical improvements in developmental engineering for livestock production, including their practical utility in the field. The artificial production of monozygotic twins via embryo splitting is shown to increase embryo productivity, while embryo sexing capability provides added value without compromising offspring productivity, with both techniques being adequate for practical field applications. It is also shown that: (1) the development of nuclear transfer utilizing oocytes collected from slaughtered ovaries and matured in vitro enables producing a large number of cloned embryos, (2) the intracytoplasmic injection of somatic cell improves the productivity of nuclear transplantation, and (3) the injection of sperm increases the rate of normal oocytes with male and female pronuclei allowing further preimplantation development. Finally, the removal of cytoplasmic lipid droplets from embryos following centrifugation alters an embryo's intrinsic sensitivity to low temperature allowing long-term preservation. Collectively, these techniques have clearly provided improvements in developmental engineering for livestock production.