Thought you'd be interested to see some pictures of the slow feeders we built for our horses...they are easily adaptable to any type of fencing:

One modification that may be useful for some (rather determined) horses is to make the opening at the top about half the size - or attach the net so that it covers half of the slanted opening at the top. Either that, or use more netting, so that it hangs low enough, and make the feeder taller. I've seen a couple of horses quickly figure out how to toss the hay out the top by bumping the net with their heads. Not that it does them any good -- the hay then lands outside the pen -- but still a pain! This modification quickly fixes that problem! Maria Siebrand maria@thoughtfulhorseman.com http://www.thoughtfulhorseman.com

They LOVE them, and it takes a full eight hours for them to finish what used to last them 2 hours, tops!