Genetic improvement in poultry

Modern genetics was conceived based on observations of heritable morphological traits of chickens. The next 100 years saw the development and application of quantitative genetics and molecular sciences, which has resulted in the many modern poultry products available in the marketplace. One must recognize that not only has the performance of poultry changed over time, but many other aspects of the world have also changed that affect production and performance including feeds/nutrition, population, and consumer preference. The greatest single boost to poultry efficiency, however, has come from the application of quantitative genetics for the selection of faster growing meat-type animals, and for the selection of improved table egg layers. These efforts resulted in birds with vast improvements in growth, and other traits that were relatively easy to measure. However, quantitative genetics was not useful to improve traits that were difficult or expensive to measure such as disease resistance, which required a molecular approach. The modern era of avian genomics can be traced to the development of genetic linkage maps based on molecular markers in the 1990s. Since the first chicken genome sequence was published in 2004 the availability of genetic markers for use in breeding is no longer a limitation. Modern genomic selection has accelerated the progress of trait improvement and provided breeders with tools to rapidly select products for specific market demands including varied rearing environments, body compositions, and disease resistance