I Google it, and apparently the ALC claims they do
Thanks!
Hi, I have been reading about Fibromelanistic (aka black skinned) roosters being crossed with white leghorn hens to create female offspring with dark skin and male offspring with yellow skin. Most of the literature seems to be centred around Silkies being the fibromelanistic rooster but I am wondering if a Black Sumatra rooster could be used to create sex-linked offspring or is there a dormant gene that would stop it from happening ?
Fibromelanosis is not really the important gene for making sexlinks like that.
The sex-linked gene that matters is called Id for Inhibitor of Dermal Melanin. The dominant form of that gene blocks melanin (black pigment) from forming in the dermis (part of the skin.) The recessive form of the that gene is the one that allows dark pigment to show in the skin, and is required for a chicken to show fibromelanosis.
A chicken can have dark skin on the legs without having fibromelanosis. Examples would be any breed with "slate" shanks (Hamburg, Ameraucana, and others.) Willow/green shanks also have the gene that allows dark skin.
If you cross a rooster with dark shanks to a hen with light shanks, you get daughters with dark shanks and sons with light shanks. Fibromelanosis can make the differences more obvious, but it cannot produce sex-linked effects except when you have the sexlinked dark/light skin gene blocking it (light skin) or allowing it (dark skin).
If you have chickens with the genes for black feathers, that complicates things, because the genes causing black feathers can also cause black in the shanks. An example is Barred Rock, which has genetically "light" skin but can show black on the legs anyway.
Chickens with genes affecting black can have effects in the skin of the legs as well. Black chickens can have black on the legs, blue or splash chickens can have less black on the legs, chickens with Dominant White (turns black into white) can have little or no black on the legs, chickens with white barring can have less or no black on the legs.
White Leghorns tend to have the genes for black feathers (can cause black on the legs), and Dominant White (turns black into white, and can lighten the legs again), and they sometimes have blue or barring or both (can also lighten the legs.)
If you cross a rooster with dark skin (such as Sumatra) with a White Leghorn hen, all the different effects on the legs may make it hard to tell what is actually going on.
I have had some sexlinked chicks that did not have any of those genes to confuse matters, and still had trouble sexing them. Some pullets hatched with light feet and took a few days or weeks to darken up. Some pullets had "dark" legs that were actually a pale blue or green color. At least one cockerel had genetically "light" legs that actually looked gray (no idea what genes were causing that, but his legs were as dark as the light-looking "dark" legs on some of the pullets.)
As a practical matter, I can't say whether crossing a Black Sumatra rooster with a White Leghorn hen would give chicks that can reliably be sexed by the color of their skin, or not. You would probably have to try it and see what results you get.
