Any dog can be conditioned to not kill your chickens and hang around your farm and bark at stuff. Some breeds of dogs are more apt to alarm bark at intruders etc. Herding breeds (Border Collies, Australian Shepherds, Australian Cattle dogs etc.) usually tend to bark. They also really enjoy human companionship so you may find they require more from you than a true livestock guardian breed. Those breeds are used to being independent and that is why they do so well in that type of situation.
Depending on how much you want them to be with the chickens you may do better with two dogs that have each other to interact with. They will be happier that way. Lots of farms/ranches have a group of outside dogs that hang out and let you know that people are coming and that something has shown up. Keep in mind that they will also bark at night as part of the job so consider if that might bother you or your neighbors.
I run a dog boarding facility and also have 3 dogs of my own. My dogs are inside outside dogs and have never been trained to protect the chickens but their presence and the fact that they bark and run around the property all day keeps predators at bay. I have never lost a chicken to a predator and I live in the wilds of Montana. My chickens free range during the day and are locked up at night.
I think dogs may help your situation but may not completely solve the problem while you are away. If there was a way to lock the chickens up at night while you were gone I think you would have a much better chance and the dogs would do a better job.
Edited by BuffyBugSlayer - 4/4/16 at 9:51am