This will vary with the quality and amount of growth in the area, and the size of the donkey. Obviously Mammoths will need larger areas than Miniatures or Small Standards. If possible divide pastures and alternate from one pasture to another. When a pasture is at rest the long grass and weeds can be trimmed down well before the animals are to be returned to it. Harrowing the pasture will help to spread the manure and reduce parasite problems.
Donkeys quickly learn to be very respectful of electric fence.
From mid-May to early September, pasture will provide enough to meet the nutrient requirements of donkeys unless drought conditions exist. Make the change from dry food to grass slowly in the spring, to avoid health problems such as grass founder. Allow donkeys on pasture for thirty minutes per day at first then gradually increase the length of time each day, donkeys should be turned out after they have been fed dry feed. After a week, the donkey can stay on pasture all the time. Feed and Water Provide fortified trace mineralized salt in block or loose form in the pasture or by the shelter.