"Effect on Disposal of Cattle Mortalities
Sources of carcasses that will require non-feed disposal as a result of this final rule will be all
types of cattle producers except those whose cattle mortalities are picked up by or delivered
to rendering or pet food facilities where either the brains and spinal cords are removed or the
animals are verified to be less than 30 months of age. Those rendering and pet food
operations that remove the brain and spinal cord so that the remainder of the carcasses of
cattle mortalities can be used in animal feed without violating this final rule will have small
volumes of material requiring non-feed disposal."

"Similarly, pet food manufacturers are
expected to meet the requirement in the final rule to first remove CMPAF before subjecting
material to the mechanical separation process...

Effect on Disposal of Slaughter By-Products
Slaughter establishments have been routinely removing the brain and spinal cord from cattle
over 30 months of age to comply with USDA and FDA regulations that prohibit the use of
SRMs for human food. These parts are now commingled with other offal. As explained in
more detail later in this document, it is expected that to meet the requirements of this final
rule, federal and state inspected slaughter establishments that kill older cattle will modify
their animal killing operations to arrange for the separation of brain and spinal cord from
other offal and the delivery of the materials prohibited by the final rule to a non-feed disposal
operation. Under the final rule, the remaining offal would continue to be available for
rendering into non-ruminant animal feed."

from:
ENVIRONMENTAL ASSESSMENT
for
AMENDMENTS TO
21 CFR 589
SUBSTANCES PROHIBITED FROM USE IN
ANIMAL FOOD OR FEED
5 589.2001 Cattle Materials Prohibited in Animal Food or Feed to Prevent
the Transmission of Bovine Spongiform Encephalopathy
FINAL RULE
FOOD AND DRUG ADMINISTRATION

http://www.fda.gov/OHRMS/DOCKETS/98fr/FDA-2002-N-0031-ea.pdf

Or in a nutshell from the guidelines:

The regulation prohibits the use of certain cattle origin materials in the food or feed of all animals.
The following materials are prohibited in all animal feed by the new rule:
•
The entire carcass of BSE-positive cattle;
•
The brains and spinal cords from cattle 30 months of age and older;
•
The entire carcass of cattle not inspected and passed for human consumption that are 30 months of age or older from which brains and spinal cords were not effectively removed or otherwise effectively excluded;
•
Tallow that is derived from other materials prohibited by this rule that contain more than 0.15 percent insoluble impurities; and
•
Mechanically separated beef that is derived from the materials prohibited by this rule.