Donkeys are becoming common as pets, and mules have a large following of equine folks. We must realize donkeys are quite different than horses from a nutritional standpoint as they are efficient at digesting poor quality fiber. As the donkey had adapted to surviving on poor quality feed, if donkeys are fed as miniature horses they will become obese and develop serious health problems. It is suggested that donkeys ingest about 1.5 percent of their body weight in dry matter, which would be hay or grass, so for a 400-pound donkey this would be about six pounds of hay or grass per day. A miniature horse or pony at 400 pounds should get at least two percent of their body weight in hay and grass, which would be at least eight pounds or 25 percent more feed. You can see that feeding donkeys and mules as you feed horses will cause them to become overweight quickly.
The forage donkeys need is not improved pasture like you may be feeding horses and cattle, but with a low energy value so they can eat enough to satisfy their appetite but not become obese. Protein levels have not been established for donkeys but preliminary data indicates they need less protein than horses. As far as vitamins and minerals, generally levels required are about the same as for horses. In most cases, donkeys do not need to be given sweet feed or any concentrate feeds unless you want to use a small handful daily for training purposes. Donkeys may even do well on barley or wheat straw, and although some have been concerned this could lead to colic or stomach ulcers, studies have shown this is not the case. Unfortunately, we see lots of donkeys with laminitis and founder because they are grazing improved Bermuda grass pastures.