Submitted to: International Symposium on Porcine Reproduction on Artificial Insemination
Publication Type: Proceedings
Publication Acceptance Date: 5/20/2001
Publication Date: N/A
Interpretive Summary: Implementation of methodologies for long-term embryo preservation and transfer in swine would provide a foundation for effective utilization of the world's most valuable genetic resources on a global basis while modernizing production and enhancing genetic improvement programs. Methods exist to produce and preserve sperm, oocytes and/or embryos from genetically superior animals of most of our livestock species except the pig. Recently, there have been reports of live offspring production following transfer of frozen/thawed and vitrified/warmed pig embryos. Highlighted is the global progress in pig embryo cryopreservation. Cellular and molecular biology was used to understand the hypothermic sensitivity of pig embryos. Development of delipation technology provided the first evidence that intracellular lipid was linked to hypothermic sensitivity. Cytoskeletal stabilization and vitrification produced live offspring from vitrified/warmed and transferred embryos. Further, technology has been developed for cryopreservation of pig morula. Although improvements and refinements of the technologies will continue, the time is here for the swine industry to consider pig embryo cryopreservation as a tool for swine production and propagating select herd genetics while maintaining germplasm resources for the future.
Technical Abstract: Conservation of genetic resources is essential for availability to desirable genes and germplasm in meeting the varying needs of the future. Banking of germplasm from desirable animals of unique genetic, production and disease resistance traits will facilitate acquisition and characterization of potentially useful germplasm, ensure genetic variation thru preservation of selected stocks, and facilitate utilization of germplasm in research and industry in the future. Implementation of methodologies for long-term embryo preservation and transfer in swine would provide a foundation for effective utilization of the world's most valuable genetic resources on a global basis while modernizing production and enhancing genetic improvement programs. Methods exist to produce (in vivo and in vitro) and preserve sperm, oocytes and/or embryos from genetically superior animals of most of our livestock species. While methods exist to produce pig embryo in vitro and preserve boar sperm, there has been little success until recently in preserving pig oocytes and embryos. The use of embryos enables preservation of maternal genetic information, and in addition to sperm, represents a major increase in the efficiency of transmitting improved genetic potential in a form other than the live animal (Dobrinsky, 1999a). Surgical embryo collection and transfer methods are routine procedures in many pig reproduction laboratories. As perishable entities, embryos can survive in vitro for only a short period of time. Although embryos can be cultured up to seven days, the longer the culture period in vitro, the less likelihood of individual embryo development in vivo after transfer. The problem is related to embryo culture, as there is no medium available which will support in vitro mammalian embryo development equivalent to the in vivo environment provided in the uterus. If indefinite embryo preservation were available, the factor of culturing embryos in vitro would be minimized and embryos could be transferred shortly after recovery from long term preservation.