USDA : Cattle must be able to walk to slaughter ; slaughter is for ` ` . '' Rule was instituted to protect food supply from spread of mad cow disease . Critics say no downer cattle should be introduced into food supply .
USDA : Cattle must be able to walk to slaughter ; reinspection required for `` downers '' Rule was instituted to protect food supply from threat of mad cow disease . Critics say no downer cattle should be allowed into food supply .