Methods of conserving gametes and embryos of farm mammals

There are several methods of preserving domestic animal genes. In the present paper methods using frozen germ plasm are considered. Except in the mare, birth rates of more than 50% are obtained from deep-freezing spermatozoa. The freezing of oocytes has not been used yet in all domestic animals, but the techniques of freezing cattle, sheep, goat, rabbit and recently horse embryos are being developed. It is not yet possible to use these techniques in the pig. The success of gene preservation programmes depends not only on the technique used, but also on the efforts made by breeders and official organizations.