- CWD belongs to the family of diseases know as transmissible spongiform encephalopathies (TSE). Mad cow disease is the best-known TSE, and it's believed that England's cattle developed mad cow from feed containing rendered animal by-products. Specifically, the feed used protein and bonemeal from sheep, and English sheep have a 250-year history of scrapie, another TSE.
- Research shows that TSEs can jump from one species to another. So after English cows ate feed containing scrapie-rendered sheep the cattle eventually contracted mad cow disease in the mid-1980s. The disease spread even faster once mad-cow-infected cattle were rendered into protein and bonemeal that was then fed to other cows.
- During the late 1980s Wisconsin deer from the CWD area were very likely fed protein and bonemeal from rendered animals, including other ruminants, according to Mike Irwin, an area farmer, deer hunter and journalist who has been researching Wisconsin's CWD outbreak.