Not necessarily due to mixing. It has to do with lowered fertility in roosters pure for rose comb as I said right before. And in hatchery stock large breeding flocks, it is going to naturally float around for this reason.
It is also present in other rose combed breeds to varying degrees for same reason. Even in some show stock lines.
It is also present in other rose combed breeds to varying degrees for same reason. Even in some show stock lines.