I cracked what appeared to be a failed egg and the embryos was still alive

[ChickChickChickChick]

I like to leave them until either 1. it's clear it's nothing but goop or 2. I can smell the egg.

Could you describe the smell?

 

[Shezadandy]

Could you describe the smell?

Simply put : Death. If you've got the eggs in an incubator, especially one with a fan and one starts to go bad, it should be noticeable. It takes a little longer to notice under a broody hen - some hens will kick out dead eggs, some won't - something will smell off.

It's like walking by a spot where a rodent has died in a wall or under something heavy like a ton of hay on pallets - that kind of thing. I wouldn't recommend a deep close sniff … it's powerful.

Generally it's easy enough to tell by candling which have quit, but with really dark olive or dark brown, it can be hard to see detail. Just had one that was very hard to tell - the broody was done sitting and had left this one egg behind, stone cold when I found it. The lack of smell and very, very close scrutiny showed movement - not so much that I was 100% confident it wasn't just my eyes playing tricks. Sure enough the little booger hatched a couple days later and was quite healthy and active despite having gone cold for a while.

 

[careeka22]

I just made the same mistake on a week old egg. I couldn't see anything, looked like a blood ring and air cell was completely detached. But when I opened it there was a perfect baby still alive. I froze and didn't know what to do. I put it back in the incubator but I knew it wouldn't live long, when I had opened it the yolk broke. From now on I'm waiting until 100% sure, especially with the darker eggs. With yours it would have likely passed, mine too most likely but still sucks seeing them alive and helpless : (

 

[Shezadandy]

I just made the same mistake on a week old egg. I couldn't see anything, looked like a blood ring and air cell was completely detached. But when I opened it there was a perfect baby still alive. I froze and didn't know what to do. I put it back in the incubator but I knew it wouldn't live long, when I had opened it the yolk broke. From now on I'm waiting until 100% sure, especially with the darker eggs. With yours it would have likely passed, mine too most likely but still sucks seeing them alive and helpless : (

Ugh, sorry to hear that. I think many wait until Day 10 before discarding - shouldn't hurt the other eggs (always use your nose!!) if it goes a few days at that early stage.