Here's it written out:
Cochin has two genes for barbed feathers, I think I called that B?
So BB
The silkie has two genes for silkie feathers, I think I called that s.
So ss
The capital letter is dominate, the offspring get one gene from each parent.
So BB x ss gives you the following possible outcomes. Bs, Bs, sB, sB
All are the same. A barbed feathered bird hiding the silkie gene.
If you took one of those and bred it to a sibling
Bs x Bs. You'd get BB, Bs, sB, and ss. So only 25% chance of silkie feathers.
However if you bred one of those f1s to a silkie, you'd get
Bs x ss. Which gives you Bs, ss, sB, ss. So 50% silkie feathers.
Hope that makes sense and I'm not boring anyone. I love this stuff. I'm finding the chicken color genes very challenging. I've been trying to figure out my autosexing breed and am really confused. That's interesting about the toe genes. I suspect four toes is recessive (so it will keep popping up unexpectedly, but less and less frequently as you select against it), 5 dominate, no clue on the 6!