Arrange to borrow a sheep from a friend, neighbor or through local advertising. A pet sheep may be a little easier to handle than a farm sheep, although both will do the job.
Look over your orchard for plants poisonous to sheep. These include ragwort, ivy, and yew. Yew is lethal; so if you have a yew tree, do not let the sheep near it. If you are unsure about whether or not a plant is toxic, pull it up and remove it or check with the sheep's owner.
Use temporary wire mesh guards on young trees, unless the owner is certain their breed of sheep won't strip the bark. Just circle the base of the tree with wire mesh and secure with wire. Unlike deer, sheep are not determined bark-strippers and this should be sufficient to deter it.
Tether the sheep, unless your orchard has secure fencing. A tether of a few yards is sufficient; just move the tether and sheep as it eats the grass.
Provide a bucket of fresh water for the animal.
Check the sheep every hour to ensure it has not become entangled in the tether, kicked over the water bucket or has any other problems.