This has not been my experience. In my experience, a young cockrel raised with pullets is a terror to them. A more mature rooster will leave the pullets alone until they are POL, while a young cockrel will not. Yes, there is a bit of size difference, but a good rooster gets the job done, while a young cockrel has an over abundance of sexual energy, and won't give the young girls a break. He will also be bigger than same age pullets.