ATLANTA -- The Georgia Department of Education has ordered more than two dozen school districts across the state to stop serving beef supplied by a California slaughterhouse under federal investigation for mistreating animals.

Georgia Schools Superintendent Kathy Cox says 28 districts, including Clayton, Cobb, DeKalb, Fulton and Gwinnett counties, have pulled the meat after the U.S. Department of Agriculture alerted state officials that it could be tainted. Cox says officials won't know for sure whether the meat was tainted until Feb. 19 when federal authorities finish their investigation into the Chino, Cal.,-based Westland/Hallmark Meat Company.

LIST: Of Schools That Pulled Meat

"We have no evidence any of the meat was tainted," Cox said in a hastily called news conference at the Department of Education offices in downtown Atlanta. "I believe the cautious approach was the right approach."

Federal officials are looking into whether the slaughterhouse shipped meat from disabled animals -- known as "downer" cows because they are considered too sick or injured to walk. Federal regulations call for keeping downer cows out of the food supply because they may pose a higher risk of E. coli, salmonella contamination or mad cow disease.

The facility is a major supplier to a USDA program that distributes beef through the National School Lunch Program.

Georgia officials do not know if the suspect meat was served to students. Cox says there are no reports of students feeling sick.

Once the results of the federal investigation come out, Cox said state officials will decide whether to keep the 178,000 pounds of meat or destroy it. If the meat is cleared, schools might still be able to use it if they have stored it properly, she said.

States have been banning the Westland meat in schools since the USDA alerted states to the potentially tainted beef on Jan. 31. Those states include Idaho, South Dakota, Hawaii, Montana, Minnesota, Oregon, Iowa and Washington state.