Thanks Tim ,,,,, my mentorChicken Genetics 101
The dominant white is used in sex linked crosses (silgo cross) to eliminate any black color in the down- this allows for the red to fully express itself in the down of the female chicks. With out the dominant white, the black pigments can cover the red pigments. White leghorns (Wl) are black under the dominant white. If a person crosses a Wl with almost any variety of bird the offspring from the cross will be black under the dominant white. The WL carries black pigment producing genes that are dominant or epistatic over the genes found in almost all other none-white varieties of fowl.
A white chick could have red down but the black covers the red and the white covers the black- so you end up with a white chick. The key is to eliminate the genes that produce a black chick this leaves the red to be expressed through the white.
The dominant white gene does not effect the red color in the down of gold chicks. It only inhibits the expression of black in the down of the chicks. Some heterozygous chicks ( they only carry one dominant white gene) will have white down with very small black patches.
To use white leghorns to boost the egg production and at the same time produce a male gold side and a female silver side of a silgo cross would require some time and effort to produce.
Dominant white can be used in red sex- linked crosses- it can not be used in a black sex linked cross. In my article on sex linked crosses- I suggest not to use white birds because a person never knows the color under the white. Birds that are black under the white can not be used in a red sex linked cross. White leghorns are black under the white.
Tim
