Thanks, I'm trying to understand. Knowing if a blue gene "switch" is on is determined how? By the blue egg? I don't get the dominant thing either. Why would my totally white rooster be black dominant (which I was told, and that he would ALWAYS create black chicks)? This seems to be the case, but I just don't get it!!!
Er, chicken feather colors are a little trickier and I don't know as much about. They're not simple genes like egg color and often have dominance trees and express differently on males vs females (like how roosters are very different colors than hens).
Dominant/recessive is just a reference to many On switches it takes to show a gene. So a simple dominant gene just means if you have one copy of it, it is expressed.
And recessive means that if you have one copy of it it doesn't express. So a recessive gene means you can carry a copy of it without it showing up. It takes two with a recessive, like a lightswitch and pull string on a ceiling lamp - if they're not both on there's no light.
For feather colors there's dominance trees that determine which color will show up first. It's kind of like paint colors. Like black/red. If you have an animal that is black, it might be carrying red but you can't see it because the black is too dark to see the red color. If you paint something red and then paint black over it, it's still got red paint, you just can't see it anymore. So genetically an animal may carry the genetics for red color but you never see it because it ALSO carries black and the black overwhelms the red.
Often times white colors (and for that matter, any patterns) are characterized by totally separate genes than color alone, one that just determines whether or not there will be any color at all, because white is the absence of pigment, not a color itself.
Almost like painting with paint that's only visible on some surfaces. You still paint the animal red, then black on top. But it only shows up in specific spots. This is how barring works (a gene says the bird is X colors, then another gene says 'color doesn't show up in these places') and I assume it's how your own birds feathers work. Your chicken is probably genetically black but has another gene that is harder to pass on (maybe it is recessive or requires a particular group of pairs in a certain order) saying "no color allowed". But I know very little about dominance trees in birds, only mammals.
But this is all very complicated and may require some studying. Blue eggs are a simple dominant and egg color is pretty simple because outside of particular shades, there's only 3 major colors - white (no color), blue (shell pigment), and brown (shell coating).
So if a chicken lays a blue or green egg it's guaranteed to carry at least one blue egg gene turned "on".
If their offspring always come out laying blue or green eggs, no matter who you breed them to they'd be guaranteed to have two blues "on".
If they do not lay a blue/green egg they have no copies of the gene.
From there a simple punnet square as shown above helps you track your egg colors.
