Genetics in theory question

[BGcoop]

Ok, I was reading a thread about the genetics of cream Legbars and I got to thinking. If an Ayam Cemani(which I am told is a white or tinted egg) is bread to a cream Legbar(blue egg layer) that Should produce a blue egg laying bird, correct?
I have cemani roos that bred with my hens (rir, EE, glw, bo) and most of the chicks are mostly black in color. So I am assuming a cemani bred with a cream Legbar would also produce a nearly black chick.
My question is this: theoretically could someone eventually produce a cemani(all black chicken) that lays blue eggs? That would be pretty cool!

 

[nicalandia]

My question is this: theoretically could someone eventually produce a cemani(all black chicken) that lays blue eggs? That would be pretty cool!

A Cemani Rooster mated to a Cream Legbar hen will produce dual sex links, dermal inhibitor sex links(females id+ boosting Fibromelanosis and males will be Id which inhibits melanin expression) and sex-linked barring.

The F1 pullets will be All black(Cemani looking, black skin, black combs) that lay light blue eggs on the first cross, crossing back those females back to Cemani will enhance the Cemani type while producing 50% of the chicks with the blue eggshell(50% of the females) but you will not know which one carries the blue eggshell until the back cross females start egg production.


The males from the F1 cross will be barred, clear white skin due to sex-linked dermal inhibitor Id inherited from Cream Lebar hen, so if you cross a Cream Legbar rooster to Cemani hens all of them will be clear white skin barred.

 

[The Moonshiner]

That's a start but then what?
Assuming you would start with AC rooster over CCL hens. Where would you go after you have the F1s to get to final product?

 

[nicalandia]

Assuming you would start with AC rooster over CCL hens. Where would you go after you have the F1s to get to final product?

The logical path would be to get these F1s Hens which would be E/e+, id+/-, Fm/fm+, O/o+, p+/p+, and cross them back to Cemani stock to homologate the Extended black, Fibromelanotic loci while trying to keep the blue egg shell gene in the back cross hens

 

[The Moonshiner]

So just keep females from each generation and breed back to AC for as many generations as it takes to get back to AC type. Only breeding blue egg layers forward then when you get back to type save some pullets and also cockerels. Then test breed cockerels to determine if they carry blue egg gene.
Then breed those cockerels to the pullets then keep test breeding all offspring until you find the ones that carry two copies of blue egg genes. Then move forward with those as the finished project?
That's how I would do it but that's a lot of test breeding, playing the odds and waiting to see what test breeding offspring carry.

 

[nicalandia]

That's how I would do it but that's a lot of test breeding, playing the odds and waiting to see what test breeding offspring carry.

That is the Only way to be sure when we are dealing with the single comb blue eggshell recombinants.

Interesting enough the Chilean stock that Dr. Punnett got in early 1930(from Clarence Elliot's 1927 trip to Chile) where Single Comb already and is from these single comb recombinants from where the blue eggshell gene was derived from on the Cream Legbars and Isbars.

The blue eggs shell gene(O dominant mutant, where o+ is the wildtype none blue eggshell gene) is closely linked to the P allele(p+ wildtype, where P is dominant pea comb mutation) about 2 to 4 map units or centimorgan of distance. This means that if the blue eggshell gene is already linked to a single comb gene(in this case the gene coming from the Cream Legbars) it will follow that gene 96-98% of the times.

The Cemani/Cream Legbar F1 pullets will inherit p+/p+ from both it's parent, but once this F1s are crossed back to Cemani, only the pullets that have inherited the p+ single comb gene that is from CL, only those pullets will lay blue egg shells, how can you tell which of these backcross hens will lay blue eggs or white eggs? there is no way until they start laying

 

[Amer]

I second Nicalandia.