The potential of cryopreservation and reproductive technologies for animal genetic resources conservation strategies

Many local breeds are currently at risk and allelic diversity within breeds declines due to the global use of a limited number of commercial breeds and inbreeding. As local breeds may be considered cultural heritage and genetic diversity is necessary for ongoing genetic improvement, prevention of further losses should have top priority. Genetic diversity of farm animals may be conserved by stimulating in situ use of local breeds and by taking breeding measures to limit inbreeding, but these efforts need to be complemented by gene banking; ex situ cryopreservation of germplasm. Gene banking may serve various purposes, which call for different strategies. Short term storage, with regular updates of gene bank stocks, may be actively used for breeding in small populations, to increase the virtual effective population size and minimize inbreeding. Longer term storage of germplasm may serve to secure the breeds and the alleles for any use in a more distant future, for instance to re-establish a lost breed and to restore genetic diversity within a breed to healthy levels, or to use specific genotypes to address new breeding goals. Semen and embryos are well suited for active use in breeding to support in situ conservation of rare breeds. Oocytes may be used as well to efficiently tap the gene pool of females. For re-establishment of lost breeds, embryo transfer would be the method of choice, as it would not require backcrossing during many generations. In birds, the use of cryopreserved primordial germ cells would have similar advantages. For securing genetic diversity and preservation of alleles for the long term and for research purposes, cryopreservation of somatic cells must be considered. As of 2002, the Centre for Genetic Resources, The Netherlands (CGN) receives government funding for various tasks related to conservation of genetic diversity of farm animals, including gene banking activities. The European Regional Focal Point for Animal Genetic Resources network plays an important role in exchanging experiences and good practices between countries. Moreover, the European Commission (AGRI GENRES program) recently funded two projects (HERITAGESHEEP, EURECA) that included cryopreservation components. The fact that breeds may be found in European regions that exceed national borders and the fact that considerable gene pools of a breed may be available in other countries than the country where the breed originated calls for further development of a joint European strategy for gene banking. However, the most important first step is to increase collaboration with regard to characterization and documentation, and to share knowledge and expertise between national programmes, with regard to storage and use of germplasm and of conservation genetics.