What Do Donkeys Eat? Digestive System, Diet, and Nutritional Needs Looking for hays with a greater proportion of stems than leaves will insure a lower nutritional value. The final test of a ration is to try feeding it to some donkeys and see if it is palatable, maintains weight and keeps the animals healthy. Feed a range of feedstuffs – if possible a mixture of dry forage, green forage and some concentrate – and then you can rarely go wrong.