A donkey makes an energetic playmate and will also pass on its extremely desirable traits of calmness and patience. A successful way to introduce the lone animal to the new donkey companion is as follows. Put the two animals in separate pens, across the fence from each other for a couple of days. The two animals should be fed in separate buckets or troughs, far enough apart where they won't kick at each other. The pair, donkey and horses, donkey and goat, donkey and calf, etc. will eat together, sleep together, play together and keep each other good company.
Donkeys require far less feed than horses.
A high protein feed is not suitable for donkeys. They should be fed coastal hay, not rich alfalfa. At Country Music Miniature Donkeys, we have used our little donkeys very successfully to be companion animals. We once had a little sancho goat that needed a companion. We put one of the donkey weanlings with the kid for two weeks.