Most dogs if they are well behaved and listens to their owners will know right off the bat what the owner expects of them, if they are curious and comes in to inspect the new chickens.... hold it in your hand and let your dog sniff them so they can get accustom to the scent, sometimes dogs just want to know who and what is part of the 'pack'. As an owner you have to set the rules, if your dog is aggressive at first, fenced the chickens off for awhile while still in sight and observe your dog's behavior, sometimes they will get bored and won't even care anymore and then slowly introduce the chickens while carefully supervising. But if your dog still exhibits aggressive behavior, stand between the chickens and your dog while giving a dominant posture. If your dog is obedient, he will learn that he shouldn't mess with the chickens.
When I first introduced my newly acquired pair of chicken to my dog, she didn't pay much attention to it, until one day her 'natural instinct' kicked in while I was not paying attention and heard a commotion only to turn around and see her chasing them. I immediately ran and put myself in-between her and the chickens and right then and there she kind of 'came back to' and realized it was wrong in the owners eyes. So although at most times your dog may seem friendly and unassuming around your chickens, sometimes their natural instinct might just kicked in and they will sometimes bite and kill a chicken. That happened once with a dog I used to have, was always playful with his chicken friend until one day my mother found his chicken friend dead in his mouth.