Trees are best protected from donkeys and goats by building a strong fence around them. Goats can climb and jump and donkeys are large, strong, and capable of knocking down weak fences. Use concrete to set the wooden posts into the ground at least 1.5 feet deep. Use livestock wire, barbed wire, or wood to build the rest of your fence. Make sure the fence is large enough so donkeys can’t reach the fruit from outside the fence. Be cautious of large tree roots when digging post holes.