A pair of donkeys will require a minimum of 1 acre of land on which to graze. However the pasture needs to be managed if the animals are to thrive.
It is worth considering the donkey's origin. His original habitat would have been fairly barren with minimum grass and scrubland and in order to find food it would have been necessary to travel many miles each day
Compare this with the modern donkey living in Ireland. Plentiful grass (mostly) and wet, often boggy land underfoot.
Many owners allow their donkeys to graze freely. Not ideal - this high energy food needs to be restricted, particularly in Spring when grass is very sweet. To overcome this we would recommend strip grazing (use of temporary fencing/portable battery) thus allowing only a small portion of grass to be grazed at any one time. The "fencing" is moved daily, allowing the donkey to access the new grass. If you are fortunate to have more than one field, these can be rotated but again careful management is required.
Grazing areas need to be secure as donkeys are great escape artists. Lovely thick hedges will quickly come to his attention and before long will eat his way through and/or manage to wriggle through to the other side. To avoid this it is advisable to erect post and wire fencing 2 or 3 feet back from the hedge (any nearer and he will lean over the wire to access the hedge, breaking the wire and defeating the object of the exercise!).
One of the best fencing systems is post and rail but can be very expensive. Its worth mentioning that donkeys do like to gnaw at wood - it's very natural behaviour for donkeys and doesn't mean he has any mineral deficiency but maybe that he's just bored. Its not a good idea to use creosote or similar on the wood which is toxic but a preparation called Cribox can be used or use of electric fencing to deter the offender.
Whether using post/rail or post/wire its important to ensure that the lower line is not too low (or else he will have to step over it to give it a try!) and not too much of a gap between lines (the head will undoubtedly come through to taste what's on the other side!) - we would recommend 3 or 4 runs between posts which should be positioned approximately 8/10' apart.
Don't forget to check fencing on a regular basis. If electric fencing is used, check nothing is touching the wire, even a branch or long grass can interrupt the power. Use a fence tester to identify any place where there is any power outage.
Keep an eye out for any poisonous plants that may appear such as Ragwort. This is poisonous to all equines and needs to be pulled before the flowers form.