Split Eggs ?

Split like mixed?

then no- that only gets approx as much as 75% 'pure' genes but as low as 51% depending on how the genes mixed.

Split as in color, yes they would be pure if the parents were pure. Just a different color type.

 

By split, I assume you mean two different breeds.

Genetically, no matter what the offspring looks like, a chicken from a cross of two breeds will not produce purebred chickens. There will be genes hiding in there that will not necessarily breed true. If you breed the offspring of the cross hen and purebred rooster to other offspring of that mix, they will certainly not breed true. It depends on what the cross is, but you would often be surprised at the colors and patterns that show up. Conformation enters into it too.

There is no genetic test to determine a purebreed chicken. All the breeds were developed from other existing breeds or sports of these, so they hold genes in common.

What somewhat complicates it is that there is no genetic testing at shows to determine breed. If a chicken meets the SOP for a certain breed, it can be entered in that breed. There are a lot of things that go into it besides colors and patterns. I'll just mention comb type and number of toes. There are others. It is not that unusual for good breeders that win ribbons at shows to introduce a different color or breed to his/her line to correct something that does not conform to the SOP. Through careful selection of the breeding stock, that trait gets set in his/her line and eventually, when the birds consistently breed true, they are again considered purebred. Not every chicken that wins a nice prize is a true purebred.

In a post a while back someone mentioned entering a cross into a chicken show in the New Hampshire category. As I remember it, there was not any New Hampshire blood in that chicken. I could be wrong about that, but it was definitely a cross. It did not win, but it was close enough to the standard to not get disqualified. I assume the judge was competent.