Candling possibly rotten eggs - two air sacs?


9 Years
Feb 6, 2010
Hi all -

Yesterday my mama duck was sitting on 5 eggs, 3 had a blueish cast to them. The two normal looking eggs are moving when candled, one has internally piped and I think the other has both internally and externally piped. Today one of the blueist-cast eggs had exploded rotten material all over the nest. The other two eggs with the blueish-black look are not moving, and when candled I see two air sacs in these eggs - one of the air sacs looks clear and the other kind of reddish and with dark spots. I am kind of thinking that these eggs are bad, given the dark blueish look and the funky air sacs -- and I really don't want more exploded eggs.

Do these eggs sound like they are bad? I want to throw them out of the nest and let the 2 good eggs hatch, but now I'm second guessing myself.

Well i hope someone gets back to you soon, i'm having exactly the same problem. Only mine are in the bator. I don't want any explosions in there,lol. I just had three more calls hatch but one didn't make it. These guys are realy hard to hatch. Had to help the last two again. I'll be keeping an eye on this post so i know if you get an answer. Thanks for posting.
Hi Missy - I decided that my blueish-blackish eggs were bad and took them out. Good thing too, because I had two babies by this morning and I really didn't want gross exploded rotten eggs on the babies!

After candling them really carefully, I realized that one air-sac was the "true" air sac, and that the other "air sac" was part of the rotten material (what used to be the baby). I could see reddish botchy things in this second air sac, and I'm pretty sure that's not normal. I think most eggs that look conspicuously blueish-blackish under normal light conditions must be bad. Correct me if I'm wrong, though!

Best of luck with your babies!
lilyduck--I think you're right about your eggs. Generally, comparing good eggs with bad makes it easier to tell which are which, and you've done that. At this point, it wouldn't hurt to open those eggs up (outside away from your house! lol) and have a look to confirm your suspicions. Nothing educates a person faster than hands-on observation. Just have plenty of soap and water on hand--they may be stinky!!
In my experience, dark spots visible in regular lighting are signs of a bad egg. Now, some eggs will darken like that right before hatch, as the baby takes up the space in the egg and the shell becomes thin, so you can kind of see through it a bit. But they look different, they are more uniformly shadowy, not splotchy and real dark.

My hens last batch of eggs turned into 4 dark spotty eggs like that, and all of them proved bad. We even opened one up when a crack appeared, and confirmed that the duckling had stopped developing/died late in the hatch. It was stinky once opened. I would say if you candle them and still see good veining you should wait a bit and see, but if no good veins are visible I would bet on the eggs being bad.
I agree, if they have dark spots i keep an eye on them very closly. I always open eggs that don't hatch just in case i can learn from them. Sounds gross and sometimes it is but i have learned.

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