Edited by Shaunb020 - 10/16/15 at 8:18am
The black bone trait is a complicated polygentic trait and is dependent upon the inheritance of a sex-linked gene called dermal melanin. (dm) Along with the Fm locus. To keep things simple, treat the Fm locus like an incompletely dominant gene.
white skinned chickens with slate legs carry dermal melanin (d m)
yellow or white legged chickens do not carry dermal melanin
green or black legs may or may not carry dermal melanin
when doing crosses for the black bone trait use a male that completely expresses black bone trait - this ensures that the male can pass on at least on dm gene to some of the males and to some of the females, females with dm can only pass on one dm gene to the male offspring , the female offspring do not inherit a DM gene from the mother.
No DM No black bone trait
two dm genes in males + other required genes = black bone
females can only carry one dm gene + other required genes = black bone
So if a fibro rooster is bred to a DM carrying hen all babies will be fibro?
No, the offspring will not inherit the correct number of loci to have fibro. They will be darker than other birds but not like a fibro.
Any bird that has slate legs carries dermal melanin, some birds with green legs carry dermal melanin and some birds with black legs carry dermal melanin. You can check the center of a birds foot to determine if it has dermal melanin. The center ( on bottom of foot) of a black foot will be white- no dermal melanin, The center of a green foot yellow no dermal melanin.