EMBRYO MANIPULATION AND GENE-TRANSFER IN DOMESTIC-ANIMALS

The manipulation of reproduction through artificial insemination and embryo transfer has had a major impact on genetic strategies in animal production during the last 15 years. The advent of estrus synchronization, nonsurgical embryo collection and transfer, and embryo freezing have allowed a move from the laboratory to the farm. Other aspects of embryo manipulation which have a major impact on breeding strategies include embryo splitting to produce monozygotic twins, in vitro fertilization, cross species fertilization, embryo sexing, production of tetraparental animals (chimeras) and nuclear transfer. Genetically engineered animals are now being produced, although very little of the molecular biology and physiology of increased production efficiency is understood.