Are Yolks Formed Right when they Lay?

[FunnyBunnies12]

The last 3 eggs I've candled have pretty much had light radiating through out and around the egg on the inside where as the 9 I have incubating right now have distinct yolks. I'm guessing those are my fertile ones, and now these last 3 are pretty much duds because I don't see distinct yolks. Am I right? She hasn't even begun to lay either.

 

[Boggy Bottom Bantams]

yolks are actually the first part of the egg that is formed. Some are layed yolkless, but are usually very tiny. With some candleing lights, especially just flashlights, it can be very hard to actaully see the yolk, especially if it's thick or dark shelled eggs. I would bet they have yolks if they are normal size. The presence of the yolk has nothing to do with fertility though. Once you start to see veins and a heart in the center of the yolk, then you know you have a fertile egg. With a trained eye, and good light, you can see this at day 4, anyone can see it by day 7-10 though. Give them til then before you give up on them at least