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It all depends on the rooster. Young cockerels will mate with anything they can catch, as often as they can. Mature roosters will take the time to woo a hen. He will try to find tidbits for her, show her places to lay, keep watch over her, and dance. He should not just try to grab on to her and mate right away.
If your girls are older than the cockerel, and the cockerel still isn't fully matured, it's best for the older girls to beat him up. He will learn to respect them, and be a better rooster for it. Adult hens are great for keeping randy teenage boys inline.