I wouldnt call this proof but Ive found the same info twice:
'The Food and Drug Administration and the United States
Department of Agriculture realized a decade ago that feeding rendered
slaughterhouse waste to livestock should be completely banned, but to
appease the meat industry has not done so. Instead, five years ago the FDA
passed a poorly enforced regulation that all meat and bone meal from
ruminant animals (cattle, sheep, deer) should be labeled not to be fed to
other ruminants. However, the blood from ruminants is exempt, and in
Wisconsin and other states calves are fed raw cattle blood plasma as a
protein source in milk replacer and calf starter. Cattle meat and bone and
blood meal is fed to pigs, which are fed to cattle, by the billions of
pounds a year. Deer, elk and sheep known to be infected with mad cow-type
disease can legally be rendered and fed to pigs, and pigs are fed to pigs.
Deer and elk on game farms and in the wild are fed supplemental fat, protein
and minerals even to this day. In other words, the US is widely engaging in
practices almost guaranteed to spread TSE disease in the US.
In 1995 alone, more than 26,000 road killed deer were picked up off
Wisconsin roadways and rendered into meat and bone meal used for animal
feed. Itıs possible CWD has already been spread to deer, cattle and other
livestock via such feeding practices. (July 2002)
http://www.maddeer.org/madmadmad.htmlIn May 2003, the Food and Drug Administration finally drafted up proposed voluntary "suggestions" for the rendering industry, recommending that deer and elk infected with chronic wasting disease, or at high risk for the disease, be excluded from animal feed.[21] However, even if this proposal is enacted, it represents only non-binding, non-enforceable "guidance" recommendations for the industry. The FDA made these same kinds of "guidance" recommendations to pharmaceutical companies over a decade ago, discouraging the use of bovine-derived materials from countries with mad cow disease in manufacturing their vaccines,[22] only to learn 7 years later that major pharmaceutical manufacturers simply ignored the guidelines.[23]
Europe's Scientific Steering Committee met in 2003 and agreed that the United States should comply with the World Health Organization guidelines and ban the feeding of animals infected with chronic wasting disease to other animals.[24] The United States seems to remain the only country that knowingly allows prion infected animals to be fed to other animals, including those destined for the dinner plate.
http://organicconsumers.org/madcow/GregerBSE.cfm