Fertile eggs not developing questions

[jnbelknap]

My neighbor and I have a clutch of eggs under my broody. We gave her nine eggs at the same time, and all were laid the same day. Four from my flock and five from my neighbor's flock. I know my eggs are successfully fertilized by my EE Roo due to previous hatches (see picture). My neighbor's eggs look consistently fertilized by her silkie Roos (see picture). There is a faint bullseye to the naked eye.

When we did the five day candling, we can see that my four eggs are developing, and her five are not developing. Is the only plausible reason fertilization? Do you agree that the eggs are fertilized? Are there any other reasons why a fertile egg wouldn't be developing?

Thank you for your help!

My fertilized eggs:

Her eggs:

Her eggs on left--my eggs on right:

 

[AmericanMom]

Good Morning..

Maybe it is just my old eyes but the third picture does not look fertile to me, Its not that it is clearly a pinpoint but that its not clearly (to me ) a bulls eye

Other than that, not sure why yours would develop and hers would not..

 

[howfunkyisurchicken]

It doesn't look fertile to me either, but I have a hard time seeing a bullseye when I look at these types of pics on my phone or computer.
My next thought was perhaps her roos aren't into to doing their jobs because of the time of the year. The days are still kind of short and some for some breeds, the roosters don't start feeling their friskiest until spring.

But, quite a few things can affect fertility. Food quality, general stress, illness, ect.

 

[jnbelknap]

Thank you for weighing in! I know the pictures don't show well, but I can see a faint bullseye in person. Any other opinions?