OAK BROOK, Ill. (CBS) — The animal rights group that prodded McDonald’s into dropping a major egg supplier now wants the fast-food giant to take a stand on the conditions in which the chickens are kept.

“Our concern is that McDonald’s has simply shifted the abuse from this supplier, that has been investigated and exposed, to another factory farm that is engaging in the same abusive behavior that hasn’t been exposed,” said Nathan Runkle, the executive director of the group Mercy for Animals.

In a letter dated Saturday, Runkle asked to speak directly with McDonald’s CEO Jim Skinner on such issues.

He said he wants the fast-food giant to agree to prod suppliers into abandoning the small “battery” cages used by Sparboe Farms, the supplier McDonald’s dropped Wednesday.

The group also wants McDonald’s to demand a cage-free atmosphere in which chickens can nest and can have perches and scratching posts. It also wants an end to the practice of burning off the beaks of young chicks without painkillers.

“McDonald’s is the largest egg purchaser in the United States and they have incredible power,” he said.

Runkle said McDonald’s has forced suppliers in other areas to change their practices to eliminate practices considered inhumane, and said McDonald’s in Europe already has moved to cage-free suppliers as part of an EU-wide effort.

McDonald’s had not received the group’s letter as of mid-afternoon Saturday, but spokesperson Lisa McComb said that the fast-food provider is already involved in a “giant” study of hen-housing practices and methods. She said each has its advantages and drawbacks.

Since the Food and Drug Administration issued its warning letter to Sparboe Farms Wednesday, both McDonald’s and Target Corp. have dropped it as a supplier. FDA conducted inspections at several Sparboe facilities April-June of this year, while Mercy for Animals used hidden cameras, infiltrating some of the same factory farms, May-August.

McComb said the Sparboe farm in Vincent, Ia., is the only one that provided eggs to McDonald’s, and said it was not one of the targets of the Wednesday FDA warning or the videotaping.

But McComb said it did not matter where the practices called into question by Mercy for Animals occurred.

“That’s completely unacceptable,” McComb said. “We’re not going to work with a company that is okay with that.”

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