By Dan Shapley
Chickens that live on farms that received feed tainted with melamine will not be kept off grocery store shelves, the Department of Agriculture has decided. Some farms use salvaged pet food - including food from brands that have since been recalled - to supplement their feed, so it's possible that small, but as yet undetectable amounts of melamine is in the feed fed to as many as 20 million chickens. Because there was no melamine detected in the feed, federal agents will allow the chickens to be processed and sold. Also, yesterday a laboratory investigating the pet deaths related to the tainted food said that a combination of two related chemicals - melamine and cyanuric acid - create a more toxic effect on kidneys, particularly in cats.