The agency said its final rule further protects animals and consumers against bovine spongiform encephalopathym, or BSE -- also known as "mad cow disease."

The materials that can no longer be used in animal feed are the tissues that have the highest risk for carrying the agent thought to cause BSE. Such high risk cattle materials are the brains and spinal cords from cattle 30 months of age and older.

In addition, the rule also prohibits use of the entire carcass of cattle not inspected and passed for human consumption unless the cattle are less than 30 months of age or their brains and spinal cords have been removed.

The risk of BSE in cattle less than 30 months of age is considered to be exceedingly low, officials said.

The regulation finalizes a proposed rule the FDA issued for public comment in October 2005. The FDA said the new rule is effective April 23, 2009, in order to give the livestock, meat, rendering, and feed industries time to adapt their practices to comply with the regulation.