Genetic diversity bred out of chickens

February 23, 2009 7:30:16 PM PST
In Dr. Mary Delaney's office at the University of California, Davis there is a basket of chicken eggs on one of the tables. They are not the kind you buy in a store or crack for breakfast, but the variety tells a story.

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"They could be reflective of the gene pool; you see the diversity in color, size, shape," Delaney said.

Consumers rarely see such eggs because of the demand for uniformity, but according to Delaney, that comes with a liability. She has just published the first experimental analysis for an entire agricultural commodity - chickens.

Her results are a little unnerving.

"We have narrowed the gene pool," Delaney said.

Poultry producers have spent the last 70 years improving on nature. Today's industrial breeds are not the same chickens your great-grandmother raised in her backyard. Those were not nearly as meaty or productive.

"They were pushed in a particular direction," Delaney said.

A bird that produces 300 eggs a year, all year long, is not natural. It was a product of selected breeding.

The question is now: what traits have been bred out of chickens?

"We lose what we don't even know about," Delaney said.

It helps to think of genes as building blocks with specific functions. Delany worries that by selecting away from chickens that lay wrinkled, eggs, for example, commercial breeds may not have the genetic latitude left over for future adaptations if we need them.

"We have accelerated selections for particular traits in particular lines," Delaney said.

In scientific terms: this may not be significant, at all. Or maybe it will, as a price of perfection.

A possible downside to your sunny side up.

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