My boy passed the hardest test possible for a dog and chickens. He found a deer skull while we were out in the woods and brought it home to chew on. The hens must of thought it smelled wonderful because they were very interested in it. I watched my "pit bull" American Pit Bull Terrier ignore the hens until they tried to get him to share. He gave a little growl then got up with his bone and took it to the other side of the yard. Of course they followed him! He quickly moved again and the hens gave up pursuit.
I'm not one to be to concerned with the breed of a dog. But everyone should try to know the specifics. It helps determine training. I knew the breed I have would have a strong prey drive but they also have a strong desire the please their person.
I grew up with German Shepherds and Rottweilers and we always had all kinds of farm animals and strangers/guests around. We never had any problems. Maybe I'm lucky, but I'd like to think it's the training.