Mad Cow Testing Act of 2004 - Amends the Federal Meat Inspection Act to require the post-mortem testing of cattle carcasses and parts intended for human consumption for bovine spongiform encephalopathy (mad cow disease). Requires that: (1) such tests be conducted only by Animal and Plant Health Inspection Service personnel; and (2) testing costs be covered through fees collected from slaughtering, meat-canning, salting, packing, rendering, and other establishments subject to such testing.
Authorizes the Secretary of Agriculture to delay such testing if an accurate test is not available for cattle under a certain age. Requires the Secretary to evaluate at least yearly during the course of any such delay whether a test has been developed.