My husband just reminded me of this point in the Kentucky/Rocky mountain horse history, quote from the rmhorse.com site Guess that's why they don't like fancy treats, carrots and apples
The families of eastern Kentucky who owned these horses were not wealthy and could not afford to spend a lot of money on the upkeep of their horses. Unlike Kentucky Thoroughbreds that were typically owned by wealthy people, the gaited horses of eastern Kentucky received no special care, and as a result most of the weak ones did not survive. These horses withstood the harsh winters of eastern Kentucky with minimal shelter, and they were often fed "fodder", a kind of rough silage. Some had to exist on whatever sustenance they could find. So, like deer, they ate the bark off trees when they were hungry. Only the horses that survived these extreme conditions lived to reproduce their kind.