Specifically, take a Production RIR as example, and explain why--if most have Leghorn mixed in--they are not considered a hybrid. Why do they breed true, but crossing with a Barred Rock is a hybrid that does not breed true? Another example, is with dogs. I was reading that an AKC champion in the Shetland Collie (Sheltie) class was actually crossed with a Rough Collie to better meet Sheltie breed standards. I don't understand how this was considered a pure bred or how the paperwork could make it acceptable for competition. What magic powers do animal breeders have to cross breeds without creating "hybrids"? What am I missing?