I would get rid of ONE donkey to start with. Donkeys don't really protect sheep but do protect territory. If you have two donkeys they pair up and go hang out. One donkey will hang out with the sheep if they have no one else to hang with and the sheep benefit from the donkey's territorial nature. Honestly I would not be able to stay in the sheep business without my LGD's. You have to buy the correct dogs from real working genetics. I have had donkeys. They can be better than nothing but for sure not the best option.
