ALBANY, N.Y. (AP) - The U.S. Department of Agriculture will offer schools choice in ground beef buys amid growing concern over an ammonia-treated filler critics call "pink slime."
    
Under the change to be announced Thursday, schools will be able to choose between beef patties made with the filler or bulk ground beef without it.

The policy will affect food at schools this fall because of existing contracts.
    
A USDA official with knowledge of the decision says the agency wanted to be transparent and school districts wanted choices.

The official spoke to The Associated Press on condition of anonymity ahead of the official announcement.
    
The USDA buys about a fifth of the food served in schools.
    
The controversy centers on a processed ingredient common in ground beef that is exposed to ammonium hydroxide gas to kill bacteria.