Seeing as the cockerel is so much younger then the hens, I believe that's why the hens attack him.
We hatched out about 27 chicks last year, of course some are cockerels and some are pullets. The cockerels can and do mate the pullets, but sometimes afterward the pullet will chase and peck the cockerel, just for a little bit, to show him who's boss. Sometimes the pullet will not allow him to mate her, she'll just chase him. (Yet all the pullets fully respect the older roosters, which are all 2+ years old)
Unless you NEED fertilized eggs right now, I'd leave him in a separate pen until he's a bit older.
We hatched out about 27 chicks last year, of course some are cockerels and some are pullets. The cockerels can and do mate the pullets, but sometimes afterward the pullet will chase and peck the cockerel, just for a little bit, to show him who's boss. Sometimes the pullet will not allow him to mate her, she'll just chase him. (Yet all the pullets fully respect the older roosters, which are all 2+ years old)
Unless you NEED fertilized eggs right now, I'd leave him in a separate pen until he's a bit older.