Ive read somewhere that when you take a rooster out ..the hens can remain fertile for up to a month. I guess the hens store the sperm. It was also stated if you put a new rooster in right away..his sperm overlays the old sperm. And the hen usally use the new. But if you take that second rooster out.. as she lays fertile eggs for up to a month.. you could get chicks from the original rooster. I guess my question is . To be safe wouldn't it be better to take rooster out in fall, and let the hen go without rooster..until spring and then add your new rooster?any eggs she would lay thru winter would use all the sperm up?