And it's true that very little US beef is going to Canada anymore, because when the US closed the border it sent Canadian beef prices down so far that nobody in Canada will pay the premium for US beef (save for a tiny handful of restaurants in the major Canadian cities that specialize in USDA Prime beef).
Um...I have to disagree with you here, in fact I think you've got it exactly backwards.
It's almost impossible to go into a large chain grocery store in Canada and buy Canadian beef. (at least here on the West coast of Canada anyway)
When we had our own mad cow incident here in Canada, I asked at the local grocery store why the beef prices were not lower and the butcher said that all the beef came from the U.S. anyway so there was no reason to lower the price or worry about the meat.
This frankly, angers me. I want my food to come from as close to where I live geographically as possible.
I have found only one grocery store that consistently sells Canadian beef (and good beef at that). Pricing is the exact same as for the U.S. beef, however the grade seems to be generally better and we often buy their ribeye's that melt in your mouth.
The discount or tiny grocery stores often sell Australian or New Zealand beef, the large ones U.S. beef.
Where all the Canadian beef is going is a bit of a mystery to me, but maybe we'll start to see some for a while.
We never saw dramatically lower prices as a result of BSE in Canada except for about a 4 day period when there was a huge influx of cheap ground beef from Alberta at most grocery stores, no other cuts went down in price and have not since (likely that they were from U.S. cattle anyway).