A recent study of commercial chicken populations, bred for meat and eggs around the world, has revealed that at least 50 percent of the diversity of ancestral chicken breeds has now been lost.
Led by William M. Muir of Purdue University and fellow colleagues, the analysis of ‘Proceedings of the National Academy of Sciences’ sampled approximately 2,500 birds and studied the thousand instances of genetic variation in order to calculate what a hypothetical ancestral population looked like genetically. ‘Then we were able to say what is missing,’ in commercial birds, Dr. Muir added.
This loss in genetic diversity could now leave worldwide chicken production at much greater risks from disease outbreaks as resistant genes have now vanished.
The study found that the greatest loss of diversity occurred during the introduction of wide-scale commercial production in the 1950s, and that only a small number have been chosen for cross breeding to produce broiler chickens – raised for meat – and layer chickens – for laying eggs.
Dr. Muir spoke of the difficulties in restoring diversity, stating that it is not simply a matter of crossing with more breeds as this would mean producers would lose the improvements they have made in existing lines. On the other hand, one approach could be to implement genetic markers to aid in cross-breeding, ‘to select for the parts that are good, Muir said.
New York Times