Bielefelder over RIR - sex links?

[Cluck Cluck Farmer]

The good news is That even if You can't sex the the F1 Will look very pretty

View attachment 2307819

Bielefelder x RIR? Gorgeous!

 

[NatJ]

Bielefelder rooster, Rhode Island Red hens: If you then bred a solid cockerel to their F1 pullet you would get a sex link... right?

Yes. Breeding those barred F1 pullets to a solid (not barred) rooster would give sex-linked chicks (barred sons, not-barred daughters.)

 

[Cluck Cluck Farmer]

Yes. Breeding those barred F1 pullets to a solid (not barred) rooster would give sex-linked chicks (barred sons, not-barred daughters.)

So would the "not-barred daughters" F2 still carry an unexpressed barred gene, so that if they were bred to a non-barred rooster, it would create a sex-link, or would the daughters not even carry the barred gene?

Just found the answer... "When we breed a barred hen to a solid color male, her daughters do not receive the barring gene but her sons do get one dose of barring."

 

[NatJ]

So would the "not-barred daughters" F2 still carry an unexpressed barred gene, so that if they were bred to a non-barred rooster, it would create a sex-link, or would the daughters not even carry the barred gene?

Those F2 not-barred females have no barring gene at all.

Barring is a dominant gene, so they cannot carry it without showing it. (Although white barring on a white chicken is not exactly obvious, but that's not what you'd be dealing with here.)

Barring is on the Z sex chromosome. Males have ZZ, so they can have one or two barring genes, or none. Females have ZW, so they have no more than one barring gene, or else none at all.

Males inherit Z from each parent. Females inherit their Z chromosome from their feather, and W from their mother. So a not-barred rooster will always produce not-barred daughters, no matter whether their mother has barring or not. A barred hen gives her barring (on the Z chromsome) to only her sons, not her daughters. That's how the trick works to produce sexlinks.

Autosexing breeds (like pure Bielefelders) work a bit differently. Barring has a bit of a dose effect, so a male with two copies has more white than a male or female with one copy. So when every bird has as many copies of barring as they can, they will all breed true for the trait, but the males can be visibly lighter than the females.