The prohibition affects so-called downer cattle when they are presented for pre-slaughter inspection. FSIS officials said the inability to stand or walk can be a clinical sign of bovine spongiform encephalopathy, which is also called mad cow disease.

Under the rule announced Thursday, cattle that are injured after they pass pre-slaughter inspection will be re-evaluated to determine their eligibility for slaughter. Veal calves that cannot stand because they are tired or cold may be set apart and held for treatment and re-inspection.

The U.S. Department of Agriculture's FSIS rule, published in the July 13 Federal Register, makes permanent what had been an interim final rule prohibiting slaughter of non-ambulatory cattle in the United States. The final rule becomes effective Oct. 1.