Genetic diversity takes a beating

Sunday, January 4, 2009

The tremendous increase in the productivity of poultry over 50 years has come at a cost: genetic diversity. That may come back to haunt an industry susceptible to avian influenza, says a study published in November in the Proceedings of the National Academy of Science.

The study, conducted by an international group of scientists, including those at the U.S. Department of Agriculture's Avian Disease and Oncology Laboratory in East Lansing, Mich., and the Department of Animals Sciences, Purdue, West Lafayette, Ind., compared thousands of genetic markers in standard bird flocks and those from commercial breeders.

It found that commercial poultry flocks have lost half their genetic diversity over time as companies selected for desired traits. A smaller number of companies further reduced the diversity of chickens. Reports about the study indicated that commercial broilers today descend from about three lines of birds.

Egg-producing layers come from only one specialized line.

The study's authors suggested greater diversity could be restored by interbreeding commercial chickens with indigenous or still existing varieties from different commercial flocks. BF