My understanding of donkeys as livestock protectors comes from spending some time living on a donkey sanctuary. Donkeys are often surrendered because people get them as livestock guardians and then discover that they don't always protect the livestock, and they require some care as well. (For example, like horses, they need to have their hooves trimmed. How one would manage this with 'feral' donkeys is anyone's guess...) Anyway, apparently, if you raise a female donkey (a 'Jenny') with her own foal, and whatever livestock you have, she will protect all of them as her family. A male ('jack') donkey may or may not protect the livestock but jacks and jennies alike are likely to injure or kill any dogs they meet, unless raised with dogs. They can also live to be 45 years of age or more. My two cents.