Embryo Transplantation and Preservation

Effective techniques for embryo transplantation in some laboratory and farm animals are now well established. Methods for collection and transfer of embryos in the pig were first developed in the early 1960s (Hancock and Hovell, 1962; Dziuk, Polge and Rowson, 1964; Vincent, Robison and Ulberg, 1964) and since then they have been applied mainly in research. Embryo transplantation has proved to be a valuable experimental tool in a number of studies concerned with early embryonic development, the survival of embryos in vivo or in vitro, migration and spacing of embryos within the uterus and factors affecting the maintenance of pregnancy. Future research is also likely to be concerned increasingly with cellular and genetic manipulation of eggs and embryos in vitro and the application of these techniques depends to a large extent on having reliable methods for the culture of embryos and their subsequent transfer. Practical applications, particularly in farm animals, are also important and the best example is in cattle where methods developed for research have now been extended very successfully into the practice of animal breeding. Applications in pig husbandry have so far been on a relatively small scale. The high fecundity and reproductive rate in pigs compared with cattle will never provide the same economic incentive to apply such methods for the purpose of genetic improvement or to get more offspring from a few superior animals. On the other hand, strict control of disease, especially in large intensive units, is a most important aspect of modern pig husbandry and embryo transplantation should provide the safest method of introducting new genetic material into closed herds. It is mainly for this reason, and perhaps also for the possibility of transporting embryos between countries, that embryo transplantation in pigs is likely to be applied as a practical measure.