How do roosters break their neck?

There are many ways for this to happen but, if the rooster is still alive and walking around it is possible his neck is not broken at all, that he is ill. There is a condition called "twist neck" and that could be brought on by a vitamin E deficiency. The bird will shuffle backwards with its neck stretched out and underneath its body.They will violently shake their heads and ruffle their feathers. Treatment for this is forced intake of a liquid vitamin supplement for about one week or longer.
As for a dead bird with an apparent broken neck, the most often cause is getting the head caught in the wire cage or fence, running from a predator and hitting something or a fight with another cockerel.