My Akita has been together with a brute of a cockerel in the past. That thing would attack anything and I'm sure he must have gotten him good at times but bored dog + chickens meant he was constantly following it, provoking it to attack and then run away. His favorite game. He wasn't interested in the hens much since they left him alone. He's a clever boy, just had to tell him to leave them and he knew not to hurt them although I taught him to not harm any animals which he is very good at. My mate's Akita on the other hand would kill cats, chicks, rats, depends how they are raised.
I tested him with the cockerel first but by the end I was more worried the cock was going to hurt him more than the other way round!