28/07/2026
Ever wondered what we're looking for when we candle an egg? Here's a little lesson from the farm.
Inside every egg, at the rounded end, there's a small pocket of air called the air cell. Normally it stays put, held neatly in place between two membranes just under the shell. But if an egg gets knocked, shaken or jostled about, those membranes can come loose and the air cell detaches.
When we then candle the egg and gently tilt it, you can see the tell-tale sign: the air bubble rolls and wobbles around instead of sitting still, sometimes breaking up into lots of little bubbles drifting through the white (the albumen), just like in this video. It's called a detached or ruptured air cell, and it's one of the most common things we spot when candling eggs that have been handled roughly or travelled a long way.
It doesn't always mean the egg won't develop, but a damaged air cell can make it harder for a chick to hatch, which is exactly why candling is such a handy tool for us to check what's going on inside. In this specific egg where it's fully ruptured, you can see all the air bubbles rolling around. We wouldn't bother incubating this because it's highly likely that it would not develop at all.
Sometimes, if it's just a little bit of detachment of the membrane, the egg will still successfully incubate.