Bruised egg during hatching

[Yapstan]

Today is day 28 of hatching my duck eggs (Pekin), and I went to check for any internal pipping, unfortunately still none and then I noticed some bruising on the under side of the egg so I carefully lifted it without turning to get a better look, and the bruising seems quite large. I’ve tried to research what it could be but no luck.
I would appreciate any insight into what it could be as this is my first time hatching duck eggs (or any eggs for that matter)
The humidity of the incubator is 70%, and temperature 37.5 Celsius.
I have also attached a picture of the egg

 

[Isaac 0]

Welcome to BYC!

To me, that looks like discoloration, indicating the egg is probably rotten, but before I'd toss I'd give a quick candle to check for any signs of life.

 

[Yapstan]

Thanks so much for the response, when I candle the egg is it ok for me to turn it up vertically

 

[Isaac 0]

Yes, just gently,

 

[Yapstan]

Yes, just gently,

Ok, so just candled the egg, and there seems to be a shadow where the bruised side is, but can’t tell if it’s moving. Should I keep it the same side I’ve had it up from day 25 or turn it to have the bruised side up.

 

[333113]

Sorry, that is not a bruise, and it doesn't necessarily mean the egg is bad. Candling the egg will tell you whether the egg is good or bad.

Duck eggs quite frequently develop discoloration as they incubate. If you throw away all the discolored eggs, you will have many fewer, if any, ducklings.

 

[Yapstan]

Sorry, that is not a bruise, and it doesn't necessarily mean the egg is bad. Candling the egg will tell you whether the egg is good or bad.

Duck eggs quite frequently develop discoloration as they incubate. If you throw away all the discolored eggs, you will have many fewer, if any, ducklings.

Thanks for the response, I’ll give the egg some more time.