Yes they can handle the big and little girls and all sizes in between. Ours have been quite fertile also, expect a higher fertility percentage later on, as most of our girls are still under a year old. We have a bantam brahma roo and he has had the little chicks to prove his virility (feather-feet) and all. Fathered babies with a sebright, ee, red star, and some big white chicken we don't know what she is (too big to be a leghorn, was broiler stock, but not cornish cross ).