I'm only familiar with Jersey bulls, but I wouldn't expect this to end well. Our bulls are dehorned, and I've yet to see a fight to the death, but one of them always ends up lame or bruised and battered. The younger bull starts off minding his manners, but the more patient the older bull is, the sooner the young one starts feeling his . . . oats. In this case, there's almost always a cow in heat--maybe it's different if there's not any action on the horizon.