Some male cockerels (roosters) are very territorial and can hurt small children or even someone collecting eggs or walking. Roosters will over-mate hens to the point of killing them. So this is the best reason of all to consider if you want roosters at all.

Can you keep a cockerel with chickens?

A cockerel can be put into a hen house or coop at night. The bird therefore cannot see the dawn light and will not know when to start crowing. The coop should be kept as dark as possible. If the cockerel is let out later in the morning, rather than being free roaming, this can delay the early morning crowing.

Can too many roosters kill hens?

Will a Rooster Kill a Hen? It's very possible a rooster will kill a hen if you don't do something about their aggressive behavior, yes. It happens a lot more due to over-mating than pure aggression, but it happens.