From the experience of raising chickens a large part of my 50 years:
The bad news: I've seen dogs go straight through good chicken wire, bark and scare chickens over an 8 foot fence then kill them, get into a commercial rabbit pen (1x2 welded wire with reinforced door clipped x4 with rope snaps--looked like a bear had done it). I had 50 chickens and 50 ducks killed one morning that were locked in a horse barn very tightly, top and bottom of the doors closed and latched with a horseproof latch. Dogs dug and dug until they got in. I couldn't even believe it. The next day they came back and one of the few survivors that I'd put in a live well of a live animal trap and killed the duck without really damaging the trap. Of course I didn't catch them. I had 25 goats killed and 2 horses, all by dogs. Someone's dear pets I am sure. Animal control's response was "don't you have a gun?" Yes I replied if I could only catch them at it. Laws since then say you must "make a reasonalbe effort to drive it off". We once wounded a dog that was back after our geese the next day! That sort of law just makes it so you train the dog to return when humans are not around.
The good news: After trial, error and research, I finally found the solution and it worked 100%. Livestock Guardian dogs (Great Pyranees, Kuzav, Komondor). Not Not Not herding dogs (German Shepherds, Border Collies, etc.) Their herding is one step away from hunting. And if you have both breeds you might get in trouble with your livestock guardians resenting that behavior and even killing your herding type dog...you certainly don't want the guardian to get used to the behavior--I have kept both types and keep them away from each other
I have found it best and even cheaper usually to purchase livestock guardian pups from working animals on farms. I just can't seem to find a better animal than a Great Pyranees from all aspects (tried Anatolians, just don't have the instinct to stick with the flock that I want, loved my Komondor but the coat was way too much).
But you still have to back up your Guardaians. Mine never killed any predator (and certainly were gentle with all livestock). They just roared like lions if anything came anywhere near, most predators kept on moving. On the rare occasion that something was bold enough to get close, I came out the door like a shot with a shotgun in hand and my two German Shepherds. I tried not to have to kill neighbors dogs (but with a bad dog, I certainly would) and tried to get the Shepherds to land one good bite to discourage the dog from returning. You really probably need a perimeter fence around your place and let the dogs guard the entire property, with chicken pens within. I think with a larger farm the dogs would be fine.
Oh and when you choose your pup? Don't pick it the way you do a bird dog. Pick the one cowering in the corner that is afraid of everything. That is the one that will retreat, barking like crazy, to the flock for reassurance. That way the predator doesn't know what is there...alot of dogs? Alot of livestock? Many times they say they give up and don't push their luck.
