Reproductive Innovations for Swine Production: Future Impacts of Gender Pre-selection, Embryo Transfer and Cloning

It is estimated that in the past five years, flow cytometric sorting of gender pre-selected sperm using DNA as the marker has produced over 30,000 offspring. The majority of these offspring were cattle for two reasons: 1) The cattle industry has accepted the use of gender specific sperm for commercial reproduction and 2) Cattle have a distinct advantage over swine in requiring a significantly lower number of spermatozoa for fertilization. In the swine industry, using gender pre-selected sperm has not progressed at the same pace. Nevertheless, the ability to pre select gender of the offspring in the pig is one of the most sought after reproductive innovations because it would have a huge economic impact on pork production by reducing animal maintenance costs and supporting production goals. However, the current methods for producing gender pre-selected sperm and then delivery to the uterus require development to make them more productive, efficient and cost effective in swine production. While porcine embryo transfer (ET) has been practiced for about 50 years in a research setting, it has been employed more recently to salvage a specific genotype from a disease scenario or for international transfer of valuable genetics. While ET is a practical application for modern genetic propagation, it has not received wide acceptance as a method of choice for reproduction because it requires skillful surgical embryo recovery and transfer. Further development of embryo recovery technique and non-surgical embryo transfer will lower the cost of ET and make the technology more user friendly in swine production. While one considered the future of animal reproduction, cloning (-via embryo splitting-) and nuclear transfer (embryo from somatic cell DNA) are now the reality of today. When the lamb “Dolly”, was born in 1996 as the first domestic animal cloned from an adult animal somatic cell, the fascination and fervor for the potential benefits resulting from the cloning process were launched. Since then, nuclear transfer has been successfully used to produce clones in many different species. Cloning technology will not replace traditional population genetic approaches to swine reproduction but will augment the potential to further genetic progress, increase production efficiency and improve protein quality for consumers throughout the world.