Dominant white of the Leghorn

[Cycomiko]

I have a couple pens with great crosses from my outstanding white Leghorn layer. Of course, they are all totally white except a roo that has some red on wings and one hen had a bit of black on her.
As a project for my son, we are incubating a couple of the pullets eggs x Buff Orp roo, and our white roo
over our F2 Olive egger.
My question is, does the white gradually deminish or is everything in this line always going to be dominant?

 

[Spartan22]

I say depends what nature throws at you, what gene is dominant on particular egg, your white roo seems to have some Marans in him.

Last year I breed a Pure Black Copper Marans roo with a Leghorn hen and hatch 6 eggs, all turned out to take on the Marans except one. All were feathered legs too, the one all white with some reds when matured turned out to be a roo, I had to cull. The 5 others are all hens and laying brown to dark brown eggs with pretty much took in the Marans attributes.

 

[Cycomiko]

I say depends what nature throws at you, what gene is dominant on particular egg, your white roo seems to have some Marans in him.

Last year I breed a Pure Black Copper Marans roo with a Leghorn hen and hatch 6 eggs, all turned out to take on the Marans except one. All were feathered legs too, the one all white with some reds when matured turned out to be a roo, I had to cull. The 5 others are all hens and laying brown to dark brown eggs with pretty much took in the Marans attributes.

Thanks for the real world example. I have a feeling that the roos offspring should look like a Marans build, but the hen (all red in background) doesn't have the feathered legs, got the pea comb and clean legs of the Ameraucana, but the build of the Maran. I'm just hoping for some more color in the future .

 

[sylviethecochin]

If the white is inherited, you'll be able to see it pretty quickly. It doesn't diminish; it's a gene. It's like an on/off, yes/no, 1/0 switch. They inherit it or they don't. The only thing that can change is its mode of expression.

Dominant white strips the pigment from black. It modifies the black colour. So if you have a chicken that has the Dominant White gene, but no place for black anywhere on its body, then there won't be white on its body either. A black-tailed buff Orp with a dominant white gene would not be white, it would instead have white colouring where the black is supposed to be.


Explanation below:

Extended black is what is called an e-locus gene. If a chicken is a paint-by-numbers picture, the e-locus genes determine where the lines are and what the base colours are.

Extended black means that the chicken is going to be entirely black. Any modifiers or mutations of black will affect the colouring of the entire chicken.

So your Leghorn is Extended black (E/E) with two dominant white genes stripping the pigment from that black. (I/I)

Buff Orp has a different set of e-locus genes making a different paint-by-number pattern. Orp is Wheaten (E^Wh/E^Wh). And instead of having a dominant white mutation, she is black. (i/i)

When you cross Orp and Leggy, the chicks inherit one gene from each parent. They get one E from daddy, and one E^Wh from mommy. (E/E^Wh) They do the same with the white (I/i)

Since the extended black isn't the only pattern gene that these chicks have, the other pattern leaks through a bit, especially near the throat and shoulders. Since dominant white also has black behind it, that leaks a bit too.

So you've got (E/E^Wh) and (I/i). You cross that with...oh, I have no idea what your olive Egger roo is, so I'm going to say (E^R/e+) and (i/i) (That's (birchen/duckwing) and (black/black))

So the chicks inherit one e-locus gene from each parent and one black/white gene from each parent. Now, from the mother, they can inherit E OR E^Wh. They'll ALSO inherit E^R OR e+.

That gives you four possible outcomes (dominant gene is always written first):

(E/E^R) extended black
(E/e+) Extended black
(E^R/E^Wh) Birchen
(E^R/e+) Birchen

and four more possible outcomes:
(I/i) White
(I/i) White
(i/i) black
(i/i) black.

So your chicks have a 50/50 chance of being solid coloured, and they have a 50/50 chance of having their black markings be white instead of black.