I have two partridge rock cockerels that are roughly 3 months old, and I'm wanting to get rid of them and get an unrelated rooster to put in with my hens (I have 2 buff orpingtons, a barred rock, a Rhode Island red, and 4 partridge rock hens). I'm wondering if I get, say, an Americauna roo, will he pass on the EE genes, or is the shell color/size/etc. solely dependent upon the breed of the hen? Secondly, should I get a mature roo or one closer to their age? Should I just get rid of the two I have and wait until next year to get a mature roo, after my hens are already laying? Any suggestions on breeds?