Inexperience at spotting the fertile "bullseye".

[Mrs J]

I found this, I have also been looking to see if eggs are fertile….You'll only need to open 1 or 2 in the few days running up to your incubation. When you crack open the egg, if it's fertile, you'll notice a small white spot on the top of the yolk about 4mm in width. This is called the germinal disc. This is what tells you if the egg has been fertilised. I’ll try and find some pics.

 

[Mrs J]

Hope this helps

 

[CanadaEh]

I have never seen the dark ring from the "fertile" picture in the cracked eggs that we use for cooking or feeding to our dog, yet most of them (not cracked of course) start to develop in incubator with no problem.