Are there any breeds of chickens that you're not supposed to mix? I'm not talking about your personal code of ethics in regard to chicken breeds (everyone has a different set of "chickethics" and I am respectful of everyone's right to choose their own breeds for their flocks). I am only referring to the health of the hen when laying and the health of the chicks that hatch out of the pairing. Specifically, I'm worried about size (huge roo fertilizing a small bantam's eggs or something crazy like that) - wouldn't it be too difficult and painful for her to pass that huge egg out of her small frame? I would think it would be, but I only know dogs (nothing about chickens). Thank you in advance!