Fencing??? I hope you have a strong back and lots of $$$ to spend. I have tried the Hog wire panels and cattle panels with T post about every 4' and the dang things still can get into the feeder. They just dig under it.
Like Jeffs said, I also have seen them go through a 5 strand barbwire fence and not even slow down.
The fence can be made but its going to cost you some $$$$ to do it.