In the past I got an adult mean rooster, called Gorgeous George, just to teach the dogs to leave the flock alone. He was heading for the "pot" because he had attacked everyone at that home.
That rooster, though, was a toughy. He attacked me as soon as I approached him for the first time. I trained him not to do that anymore with the gentle training techniques; finding his 'grey comfort zone' and reward him with grains when he kept his cool towards me. It took a few weeks but in the end he tolerated me. I was the only one with this honor and I loved him for it. After he had attacked my Pit mix, that dog never even wanted to look even at the baby chicks anymore. But wild life took them anyways and I gave up on chickens.