I do exactly the opposite of the name of the thread
At least 30% of my horses feed is OATS, and none of them get ' hot ' as a result, oats get bad press normally because of something else in the feed.
Unless your horse has a sugar intolerence, oats are by far one of the best horse feeds you can get.
If you had a conversation with my vet he would state that all you need to feed is - grass , alfalfa , hay and oats. He is completly baffled by people who take their horse of natural feeds and then have to supplement their man made diet because of missing vitamins etc.