There’s just one problem: ruminant tissue (including nervous tissue) is still fed to everything else. That means that chicken, farmed fish, and any other kind of meat might contain mad cow prions. To make matters worse, fish meal, chicken feces and the bodies of other animals can then be fed straight back to ruminants intended for human consumption. An extra step has been added, but the concentration of prions in animal flesh continues. Cooking does not destroy prions; even radiation leaves them untouched. Ultimately, the only way to reliably reduce your risk of mad cow disease is to avoid farmed meat products altogether.