I don't know which specific genes you're working with.I'm still struggling to remove random black feathers and correct or improve some other things.
Was hoping for advice on those stray black feathers. Some of my full Yokohama roos develop those too over time. I don't see that on the girls though, and the boys don't usually show them during the first year or two.
I wonder, if Dominant White is one of the genes, could it be that some of your birds have just one Dominant White gene and some others have two genes for it? If so, you could use test mating to sort out which group is which. (Choose a chicken of another breed that shows plenty of black, so you know it does not have Dominant White, then mate it with the bird to be tested. If you hatch 7 or 8 chicks and they all show Dominant White, the bird being tested is probably pure for that gene. If any chicks have no Dominant White, then the bird being tested has only one copy of Dominant White.)
That is a good idea, to breed from the roosters that are a couple of years old and do not show black. That should be helpful no matter what genes are actually involved.My full yoko girls show more white as they age (mottling), and the boys sometimes start showing random black feathers. I'm having the same problem with my banties but on a larger scale. Should I breed only from roos that are at least a couple years old and show no black yet? Would that fix this?
Yes, the genes from the hen would play a role in this.And do the hens genes play a role in this...and if so, how do I figure out which hens as I'm already using hens that aren't showing random blacks and I'm still getting those black feathers.
The first thing I can think of is to track which birds come from which parents, and then breed from the hens who produce sons without the black. If you know which birds are the parents of which other birds, you may be able to figure it out for your current birds.
If you have males with no black, maybe breed from their full sisters, not from hens that have a brother showing black. That would basically be using the males as testers for their parents, then selecting females from the parents that produced good males instead of the ones that produced less-good males.
	