Although we arrogant humans find their aggressive behavior unacceptable, it's how they are supposed to behave and we are the ones disturbing nature.
Except that this is not "nature" out in the wild.
This is a livestock animal who needs to be able to accept and deal with the fact that people come and go in the coop and run and who needs to have enough sense to not attack the giant who brings food.
In the wild an animal that senselessly attacks a much larger animal who was merely passing through generally dies of that aggression sooner or later.