Animal genetic resource trade flows: The utilization of newly imported breeds and the gene flow of imported animals in the United States of America

Animal germplasm exchange has recently received attention as a product of the FAO's State of the World's Animal Genetic Resources effort. Some have advocated a need to explore policies and regulations on the exchange of germplasm (e.g., Hiemstra, S.J., Drucker, A., Tvedt, M., Louwaars, N., Oldenbroek, J., Awgichew, K., Kebede, S., Bhat, P., da Silva Mariante, A. 2006. Exchange, use and conservation of animal genetic resources: policies and regulatory options. Centre for Genetic Resources. Wageningen Univ., the Netherlands, pp. 1-43). However, there has been little comprehensive assessment of either the economic or genetic impact of introduced germplasm into national populations. As a result, much of the discussion of gene flows has been based on assumptions and generalizations. The objective of this paper is to evaluate the genetic impact of germplasm imported into the United States during the last 25 to 50 years. The paper considers both new breeds (Meishan pigs, Tuli cattle, and Boer goats) and new animals within existing breeds (Limousin and Jersey cattle). Of the new breeds recently imported only one had an impact on US animal agriculture. Neither the Tuli nor the Meishan has impacted the US livestock industry. It appears that these breeds were initially viewed as attractive because of single traits, but producers did not find it attractive to adopt the new breeds based on these specific traits. In the end, these breeds did not prove competitive in the US under the current set of market conditions. This result would indicate that importation of new genetic resources due to a single trait of interest is not a viable importation strategy. By contrast, the Boer goat exhibited a number of production characteristics which made it desirable to US producers and thereby allowed the breed to become well established. A second portion of the study evaluated the importation and parentage pattern of Limousin cattle as they became established in the U. S. and the gene flow of imported Jersey cattle since the 1950's. In both cases, the study relied on pedigree analysis. Over the past fifty years, Jersey cattle have been sporadically imported from various countries, but no imported animal has had an overpowering effect on the population. It appears that by the great-grand progeny level, the genes from imported animals are diminishing rather than increasing in the population. In evaluating the predicted transmitting abilities for imported cattle relative to high and moderately ranked domestically bred cattle, there were significant differences between these groups for milk production. This would be sufficient to explain why the impact of the imported cattle diminished. The results of our analysis at both the breed and individual level underscore the speculative nature of germplasm importation -- even within breeds where there is a great deal of information available about production characteristics. From this analysis, we conclude that successful importation of new breeds into the US must be based on a large number of production characteristics; importation for a single characteristic (e.g., high prolificacy) while the breed is deficient in other areas does not lead to the breed's adoption. While not fully explored in this work, it appears that initial interest and acceptance from the private sector is crucial for breed acceptance, as the Boer goat demonstrates. Within an existing breed, importation of individual animals still appears to have a relatively high degree of risk and is dependent upon the importer's ability to pick viable candidates. However, once animals are imported their progeny must effectively compete with the domestic population, or else their genetic contribution will rapidly diminish.