Embryo manipulation in research and animal production.

Research in developmental biology has resulted in techniques to accelerate changes in gene frequency and to interfere directly in the genome. Procedures already in use or being adapted to livestock include embryo transfer, chimera production, embryo splitting, gene transfer and nuclear transplantation. Experiments with mouse embryos are revealing the principles governing embryonic development and differentiation and illustrate the need for these investigations to be extended to embryos of livestock. The optimal combination of these technologies in animal production strategies will depend upon further research and the role of animal products in society.