I disagree with most of the above posts. Dogs are all different. There is no way to answer this question.
I took in an adult mongrel stray with puppies that had been deemed a vicious dog by animal control and was going to be put down, and she has been my birds' savior. She will kill opossums and coons but is protective of the farm and my animals. She'll chase a stray cat but doesn't bother my cat; she will cahse deer but not my cows. I can free range my birds, and I totally trust my dogs. I adopted a hound mix (mostly looks red bone) from the shelter and he too is great with the birds and animals and acts as a helper to my stray adoptee/mother dog. They keep the coyotes, coons, fox, opossums, bobcats away. The geese keep the flying predators away. I free range all my birds during the day. The only losses I have is an occasional Guinea (2) that strays off the property and into the woods and one goose (when I had the dogs in the house one night). Otherwise, 48 chickens, 41 Guineas & 7 Geese free range 7 days a week and stay safe due to my two adopted dogs -- both mutts.
When I got both dogs, I spent time with them with my birds and only trusted them around my birds once I learned the dogs. You have to know the individual dog. Some will kill in front of you, some will kill when you are not looking, some will never kill and some will never kill anything & still others will act protective over the birds -- attack something that doesn't belong in their territory (my dogs) & finally, an true LGD will protect livestock even from you.