Basic demographic data - a prerequisite for effective management of animal genetic resources

摘要

Demographic data describe the size, structure and -distribution of livestock populations and how these change over time. They are fundamental to determining the risk status of breed populations both on a national and a global scale. Currently, no population data are available for 36 percent of the breeds recorded in the Domestic Animal Diversity Information System (DAD-IS), and for many other breeds data are updated so infrequently that monitoring trends in risk status is difficult or impossible. Data on the geographical distribution of breeds are also generally inadequate. A baseline survey of the breed population needs to be followed by periodic monitoring. The required frequency of the monitoring activities will depend on the generation intervalof the species in question. Data maybe collected via breed-level censuses or surveys, or estimated based on species level data. It is important that national decision-making takes account of the global demographics of the breed; a classification system distinguishing breeds present only in one country from those present in several countries has been developed. Much remains to be done to improve the availability of demographic data. Moreover, methods need to be developed that account for the risks of genetic erosion associated with indiscriminate cross-breeding. A further key requirement is the development of methods for representative sampling of national animal populations to allow estimates of their total population size and other demographic data tobe obtained in a cost-effective manner.