Originally Posted by chrissyr
rhank you all for the input .
So these were blue copper Marans cockerel over cream legbar pullet. I was told the cream legbar had to be female to do sex links.
Not the other way around. I can't confirm that.
But what kind of confused me is : why does the solid bird have to be male?
In a pure cl breeding, the male is barred.
This highlights the difference between "sex link" and "autosexing" genetics. In both case we are using the sex-linked barring characteristic, but they are working differently. With sex-link, the female parent is single barred (females are never double barred) and the male has no barring. In autosexing, the female is still single barred, but the male is double barred. In order to distinguish the chicks, the sexes must have a different number of barring alleles (1 and 0, or 1 and 2). If you reverse the sexlinked cross (male is barred) then both sexes of chicks get a single barred allele from him. If the female of that cross is not barred (solid black, for ex), she contributes no barring alleles and all the chicks are single barred, making the sexes look identical as chicks.
Autosexing is sometimes a matter of degree, depending on the other traits the chicks get that affect down color. Wild-type down (chipmunk chicks) is the best for autosexing, but some other modifiers, like wheaten and columbian can affect the wild-type colors and affect how sexable the chicks are. This is why a "pure" strain of Legbars or Rhodebars can produce chicks that are not easy to sex. It's not that they lost the barring or wild-type down, it's the other genes that muddy the waters, so to speak.
I realize this sounds confusing as I read it back to my self. Sorry, it's early, if you ask more questions maybe the next response will be a bit clearer.