S.K. Ho (1,2), E.E. Lister (2) and S.P. Touchburn (3)
(1)Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6
(2)Canadian Foundation for the Conservation of Farm Animal Genetic Resources,
Ottawa, Ontario, Canada K1Z 1A2
(3)McGill University, Ste. Anne de Bellevue, Québec, Canada H9X 3V9
*Presented at the International Conference on Animal Biotechnology, Beijing 100094, Peoples' Republic of China June 10-14, 1997
At the same time, people around the world are more concerned than ever with both the state of the environment and the security of the global food supply, of which farm animals account for 30 per cent (Hammond, 1994). This concern coincides with, and is driven in part by, a period of dramatic change enveloping the Canadian agri-food sector. Stakeholders of this sector - from farmers through to consumers - are experiencing unprecedented change in how food is produced, processed and marketed. Institutional change within the sector has meant changing roles for government, industry and non-governmental organizations. These changing roles have strengthened the need for increased cooperation. In the midst of such change, it is important to maintain a long-range vision and to ensure the basis on which we have built our food system.
There is broad agreement that a secure supply of food depends, in part, on viable populations and variety among our farm animals. The effort to promote sustainable agriculture, and to build a more secure food supply both in Canada and around the world, is based to an important extent on the genetic diversity of crop plants and farm animals used by breeders to respond to the challenges of this changing world. This paper provides an overview of where Canada stands in its effort to conserve vital farm animal genetic resources.
One of the key obligations for parties that have ratified the Convention is to prepare a national strategy. The Canadian Biodiversity Strategy (1995) is a response to this obligation and has been developed as a guide to the implementation of the Biodiversity Convention in Canada.
Protecting farm animal genetic resources is an issue that cuts across conceptual and international boundaries. Around the world, the conservation of farm animal genetic resources is a growing concern. In November 1996, commitments were made to address this concern at both the Conference of the Parties to the UN's Convention on Biodiversity and the World Food Summit, held under the auspices of the UN's Food and Agriculture Organization (FAO). At the Conference of the Parties, governments undertook a commitment to preserve agro-biodiversity, recognizing farm animal genetic resources as an element important to sustainable agriculture. At the World Food Summit, Canada joined the majority of world governments in recognizing the importance of sustainable agriculture to food security and to rural development. In the Summit's Plan of Action, Canada joined other nations to promote the conservation and sustainable utilization of both crop and farm animal genetic resources as part of the overall effort to combat environmental threats to food security.
In December 1996, Canada participated in an FAO ad hoc meeting of a group of donor countries and other stakeholders in animal genetic resources. The meeting's report noted that 30 per cent of global genetic resources are considered to be at risk. Through the FAO, Canada has supported the development and the implementation of the Global Initiative for Domestic Animal Diversity and the strategy to involve stakeholder groups at both the national and international level.
In Canada, with the support of Agriculture and Agri-Food Canada, there is a national framework of an Experts Board and a Steering Committee for animal genetic resources conservation both of which have been operating for the past five years. The Canadian Agri-Food Research Council has farm animal genetic resources conservation on its list of national priorities. The Canadian Foundation for the Conservation of Farm Animal Genetic Resources (CFCFAGR) has been formed recently with the goal to serve as the catalyst in research, educational and other relevant efforts.
Canada continues to be an active partner in the area of farm animal genetic resources conservation. A continuing commitment is being maintained to research and technology transfer efforts which protect the safety of our food supply and the sustainability of the resource base. Conservancy efforts and the animal genetics industries are both addressed by Agriculture and Agri-Food Canada in its Biodiversity Action Plan which is in its final stages of preparation. The call from both the biodiversity discussions and the World Food Summit has been for national governments to seek out partners - at all levels of government, within the private sector and academia - to find solutions to pressing environmental and food security issues. In Canada, this has been happening.
Husbandry practices for conservancy herds and flocks differ from those used in the continuous selection for farm animal productivity improvement. Blake and Price-Jones (1994), for example, published a manual on conservation breeding of heritage poultry. Agriculture and Agri-Food Canada, working with Rare Breeds Canada Inc. developed a producers' guide for livestock and poultry conservation (Chiperzak, 1994). This manual presents the philosophy, framework, strategy and the "how-to" of conservation breeding. As well, producer manuals and a computer monitoring system were created as tools for the further development of the satellite on-farm breeding network for conservation of animal genetic resources. In addition, data management systems for use by conservancy groups have been developed to track and assure parentage of rare breeds held on many farms, particularly where there is no national breed association and recording system.
Another aspect of live animal conservation is that some means of taking emergency response actions needs to be developed so that rare farm animal breeds at immediate risk can be protected until evaluated and, if appropriate, a long term home found for them. Again, with the support of Agriculture and Agri-Food Canada, plans have been drawn up for such a Rare Breeds Rescue Network in Canada (Chiperzak and Crawford, 1997). Rescue is defined as obtaining legal possession/ownership of the endangered animals, relocating them to a safe haven, and placing them permanently in a secure situation perhaps under new ownership. It is anticipated that the Network will rescue small breeding groups of recognized breeds that have become rare, as well as unique lines or strains of recognized breeds where the breeds per se are at the present not necessarily rare. The restructuring of the roles of industry and government that has been taking place in Canada adds further impetus to the implementation of measures to address this issue.
Data base establishment and access are areas of concern shared by everyone involved in conservation efforts. One of the key objectives in conservation is the rapid dissemination of information on animal genetic resources. In 1993, the work to establish Canadian animal genetic resources data bases for domestic animal breeds began at Agriculture and Agri-Food Canada. Surveys of individual breeders of goats, sheep, swine, cattle, horses and poultry have now been completed. These detailed inventories of breeds of farm animals in Canada can be a basis for establishing which populations are at risk. The data bases for goat, sheep and swine are available on both hard copy as well as in the electronic format at the CFCFAGR's homepage http://infoweb.magi.com/~cfcfagr/homepage.html.
Research and development efforts to date have concentrated on cryopreservation of bull semen (Coulter, 1992). Reliable methods for the cryostorage of bull semen have allowed the establishment and rapid growth of an artificial insemination industry for both dairy and beef cattle. Frozen bull semen is used, together with herd testing and sire selection, to improve Canadian dairy cattle productivity. The application of this technology has also resulted in the rapid growth in exports of Canadian dairy stock. The freezing of ram semen is feasible but the technology can be improved (Fiser et al., 1987). Canadian researchers (Fiser, 1995) have made excellent strides towards the cryopreservation of boar semen and the technology is approaching commercial viability. Although cryopreserved poultry semen has significant reductions in post-thaw survival (Reedy et al., 1995), it could be useful as a backup for conservation.
While embryo cryopreservation technology for cattle has been well developed for commercial use, methodology for freezing swine embryos is not yet adequate (Niemann, 1991). Poultry embryos, included in the egg with its massive supply of nutrients, are considered impossible to freeze successfully in their normal state. A Canadian group (Kino et al., 1997) has recently reported the successful cryopreservation of chicken blastodermal cells and the use of these cells, after thawing and injection into recipient eggs, to generate chimeric offspring. Indeed, this approach is currently being used to establish a gene bank of valuable chicken lines which were developed at Agriculture and Agri-Food Canada.
The efficacy of reproductive technologies such as cryopreservation, in vitro fertilization and embryo transfer would be improved by the existence of a sensitive, reliable, noninvasive test for embryo viability so that the healthiest embryos could be identified and allocated for transfer or cryostorage (Overstrom, 1996). At present, embryos are classified based only on morphology. However, this characteristic may not always be indicative of their subsequent ability to establish pregnancies and produce healthy offspring. This is especially true for embryos which have undergone significant in vitro manipulation. Carnegie (1997) and her co-workers are presently exploring the potential use of Alamar Blue, a fluorometric/colorimetric growth indicator, to identify individual embryos which are developing at an optimal rate. A culture system has been designed using this dye in which it exerted no detrimental effect on subsequent live birth rates and was able to detect the metabolic activity of as few as two healthy blastocysts. The results of initial experiments are promising.
Accurate rapid methods for determining or proving parentage of pedigreed animals are important for the breeding industry and conservancy efforts. DNA fingerprinting has replaced traditional methods. As knowledge of specific alleles that relate to superior production traits increases, these alleles could be screened as part of the same testing process. The methodology developed at Agriculture and Agri-Food Canada on the bovine kappa-casein genomic variants (Denicourt et al., 1990) is being applied through private laboratories for use by the industry.
Measuring genetic distance between populations is now a reality using modern technology. DNA fingerprinting is a valuable technique for finding the degree of relationship between populations. Other technologies include the micro-satellite technique, which is probably more accurate than DNA fingerprinting although it takes more time and resources. These techniques are useful tools in determining relative priorities for conservation efforts. There is currently a collaborative study between the University of Manitoba and Agriculture and Agri-Food Canada in measuring the genetic distance within rare breeds of domestic animals (Hansen, 1997).
Improvement in the performance of farm animals has been through selection of animals for reproduction based on their performance, often referred to as phenotype. Of course it is the collection of genes or genotype which is inherited and creates, along with environment the phenotypic performance of the progeny. Since molecular geneticists now have tools to actually identify many DNA gene codes, modern breeders would like to select genes or DNA markers which directly influence a trait.
Agriculture and Agri-Food Canada has been collaborating with United States Department of Agriculture (at East Lansing, Michigan) in research efforts to identify DNA markers which influence production traits in chickens. When analyses are completed, those DNA markers found to have a major influence on production traits can then be used in selection to improve performance. It is underscored that this work was feasible only because of the availability of well characterized chicken populations with well known backgrounds. Hence, the availability of such populations typifies the need for preservation of genetic stocks.
Genetic engineering, especially the cloning of animals, has potential as a means to conserve farm animal genetic resources. Not only will this allow the cloning of elite lines of animals - breeds with the desirable traits - but also identical animals containing, for example, a rare gene. These new techniques enable the rapid increase in numbers of rare animals through multiple ovulation and embryo transfer to same species recipients. The latest developments in the cloning of sheep using adult animal cells (Wilmut et al., 1997) could make animal genetic engineering more amenable since there is the potential to make genetic alterations to adult cells rather than just embryo cells.
However, there are really only limited advantages to a technique such as cloning to be used in livestock breeding. The issue of genetic vulnerability needs to be considered. Breeding populations rely on genetic diversity to make constant improvement. The uniqueness of individuals derives from the random mixing of genes when males and females combine to form new progeny. The possibilities are endless and it is this diversity that to date has allowed constant increases in animal productivity. Creating herds of genetically identical farm animals could be beneficial in the short term, but such herds could be particularly vulnerable, for example, to new strains of existing diseases. Cloning could be one more tool to be added to the current assembly of reproductive techniques but would require judicious use.
Agriculture and Agri-Food Canada at one time was involved in research to clone cattle by splitting embryos and implanting them into surrogate mothers and, the more sophisticated techniques of transferring nuclei from embryonic cells to enucleated eggs, with the aim of further accelerating breeding programs. This research had not advanced to the recent development of using adult cell nuclei. Agriculture and Agri-Food Canada is no longer involved in this area due to recent rationalization and establishment of new priorities of research programs. Genetic engineering research programs that are still ongoing include, for example, the trans-somatic approach of introducing genes into cattle that direct the production of value-added proteins in milk.
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