That's one of the reasons we like to kill cows off at around 30 months. if they did have BSE, It's concentrated in the spinal tissue and brain, which is why they banned mechanical stripping in order to prevent the ganglea from getting in meat.
Interesting you should say that. There was an article here just three weeks ago about some pack taking their mechanical spine stripper down (just now); it mentioned the other packs THAT STILL USE THEM.
I think they said it was voluntary...I haven't eaten ground beef that didn't come from our farm since.