A similar situation exists for modern pig populations, and, in the temperate regions, the Holstein dairy cow is rapidly becoming the preeminent, and in many cases exclusive, dairy breed. Thus, industrial stocks of chickens and turkeys have experienced no outside contributions from other breeds in more than 35 years. Although large numbers of locally adapted, relatively low-productive breeds of poultry and swine still exist globally, the elite global breeds have become so differentiated from these stocks that there is now thought to be minimal opportunity for these breeds to contribute genetic material to the elite global breeds through traditional breeding methods. Aggressive and widespread sampling and comparative evaluation of breeds in the mid-twentieth century led to the establishment of today's global breeds and to the replacement of many of the mid level, often dual-purpose, breeds that were widely represented in commercial production a few decades ago. The utilizationists have, to some extent, become victims of their successes, especially in poultry, dairy cattle, and pig production. Synthesis and rectification of the utilizationist and preservationist views is badly needed but has yet to fully occur in the animal breeding community. Retention and continued use of existing breeds in their traditional environments and production systems is promoted, even if public subsidies are required to ensure that use. Blending of breeds to generate improved, adapted commercial populations is acknowledged to be necessary and desirable, but only against a backdrop of secure and relatively stable populations of the contributing breeds. The preservationist view emphasizes the unique history and presumed genetic distinctness of individual breeds and takes breed preservation per se as its goal. In contrast to this position is a more “preservationist view” which tends to accord individual breeds a position similar to that of an endangered species and proposes similar management strategies to sustain them. In the utilizationist view, there may well be a need for a few dozen different pig breeds to meet the demands of different global production environments and markets, but a commitment to maintain all of the 656 currently recorded pig breeds ( FAO, 2010b) would be seen as excessive and counterproductive. ![]() This viewpoint, described as the “utilizationist view” by the US National Academy of Sciences ( NRC, 1993), emphasizes the potential value of the unique genes and gene combinations found in the various breeds as raw material for breed evolution and emphasizes the value in maximizing that evolution. The existing array of livestock breeds is recognized as potentially valuable but primarily as a consumable resource to be integrated into elite populations as appropriate and molded into ever-improving commercial populations. Improvement-oriented animal breeders view global genetic diversity as a resource to be used in pursuit of improved animal productivity. Despite these successes, demands for further increases in rates of animal production to supply an expanding human population continue to increase, and pressure to utilize the highly productive global breeds to meet these demands is tremendous. In other species, such as the grazing ruminants, successes have been more modest, largely because these animals are generally produced under extensive conditions and required to interact closely with their environment to harvest forages, but still have been substantial. The global proliferation of industrial production systems has relied primarily on these species because of their greater efficiency of use of harvested feeds. Successes of modern animal breeding programs have, in some cases, been spectacular, as exemplified by the emerging global breeds of poultry, swine, and dairy cattle. Indeed, most of the accomplishments of modern animal breeding have resulted from improving the accuracy of genetic evaluation of prospective parents and increasing the number of offspring of these selected parents by use of artificial insemination (AI), embryo cloning and transfer, and other advanced reproductive technologies. Thus, propagation of small numbers of elite parents yields greater rates of progress than retention of larger numbers of less-desirable individuals. Rates of genetic improvement are generally proportional to the intensity of selection. On the one hand, maximizing livestock productivity relies on the identification and propagation of superior genetic types. ![]() ![]() Irene Hoffmann, in Encyclopedia of Biodiversity (Second Edition), 2013 Conservation Planning: Coordinating the Use and Conservation of Livestock Genetic ResourcesĪnimal breeders are often confronted by an apparent dilemma in the design of livestock breeding programs.
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