Pigeony
Songster
You may have heard of the "float test", which people do for two reasons:
- To check egg "freshness" for eating eggs
- To check for life in hatching eggs that are in lockdown but aren't hatched or pipped
There is no value in doing the float test for either reason.
It does not tell you whether an egg is "fresh". Whether the egg floats or sinks tells you nothing about whether or not it is a good or bad egg for eating, all it tells you is how big the air cell is. Eggs do get larger air cells the further they are from being laid, but there's also variablity from the thickness and porosity of the egg shell as well as the humidity of the environment. Less humid environments equal more moisture loss equal larger air cells developing faster. An egg can have a large air cell and still be completely edible with no significant difference in taste.
What the float test does do is destroy the protective biofilm "bloom" on the outside of the egg meant to keep bacteria out so the egg doesn't go bad, meaning that an egg that was put through the float test will now go bad faster than an egg that wasn't. If those eggs are meant for incubation, a washed egg is much less likely to successfully survive to lockdown.
Now how about for late hatchers? Why shouldn't you do the float test?
So, an egg that hasn't pipped or hatched isn't unaware of its outside environment. They are breathing through that porous shell, there is a constant gas exchange occurring; it's why coating the whole shell and blocking up those pores would quickly result in a dead egg.
When an egg with a live embryo is exposed to water coming through those pores, they can drown. And it does not take much for a chick still within its egg to drown- I've had chicks not hatch because only a couple drops of water pooled under their eggs and that was all it took.
Yes, if it's brief and the egg is dried afterward, they may survive it, but you essentially are waterboarding the baby chick inside that egg. They know that they're floating in water, and it's panic-inducing. That is what people are seeing when the egg bobs around. That does absolutely no favors to a weak or late-hatching/developing chick; in fact when they are startled and kicking in that egg, it's entirely possible for them to nick a vein in that struggle and at the very least, they are using up energy that could be put towards hatching.
It just gives them another hurdle to get over; yes, you can still have successful hatches after the float test but you made them struggle more than they had to. Washing away that bloom also makes them more susceptible to bacteria after being floated. By getting that egg wet, you've taken away their first line of defense and the chick itself has minimal immune system.
Floating them in cool water can also drop the egg temperature much more rapidly than exposure to same-temperature air, as water has a higher thermal conductivity than air, which is another shock to the potential chick that could weaken them unnecessarily.
There is nothing the float test can tell you that candling can't tell you, and candling isn't as damaging to the egg. Although you certainly don't need to, you can candle eggs you are planning to eat.
For candling for freshness, you can see bacterial growth as shadows in the egg, you can see cracks in the shell, and you can see the air cell size.
For candling hatching eggs, despite the egg being mostly dark at lockdown in a normally developing egg, you can still look for the correct coloring, shape, veins, and breathing. At that point in development, the chick has grown in size enough to likely bulge a bit into the air cell whether it's internally pipped or not, and you can watch that dark, rounded shape for subtle movement indicating breathing.
If you see active veins, movement, and/or breathing, it's best to just put the egg back in the incubator and let it continue developing. If you're really worried and feel like you need to assist somehow, you can do a "safety hole" not too much bigger than a pinprick to ensure the chick won't suffocate even if it's having trouble pipping. A small safety hole should not significantly affect the humidity inside the egg at normal lockdown moisture levels, but the hole being too big could dry out membranes, so use caution.
Careful observation with a decent light in a dark room can tell you all you need to know, and if you see no signs of life whatsoever but are still hesitant to give up on the egg, there are further actions you can take that will give you much more definitive answers.
If you're really unsure if it's worth continuing incubation and hatching is overdue, you can make a hole in the air cell just large enough to shine a light through and see inside. Again, I don't recommend doing so until the eggs are overdue. And it's best to keep the hole as small as you can while still being able to see inside.
If you see white membrane and it's moving rhythmically to the chick's breathing, you have a live egg and take no further action except possibly raising incubator humidity slightly to compensate for the hole you made.
If you see white membrane that's not moving, wet the membrane lightly with a slightly damp q-tip. If you see active veins, raise the humdity slightly and take no further action. If you see thin red lines that preciously were veins, they don't look active and you see no movement, the chick died recently.
If you see clear membrane, the egg died some time ago and the decomposition process has begun to dissolve the membrane.
The only time the float test is justified is with eggshells too thick or dark to see through whatsoever (most chicken eggs do not fall in this category, it's mostly more exotic species of fowl), and even then it should be a last resort done only when an egg is significantly overdue to pip. The float test has much more drawbacks than benefits, and in most cases, it only satisifies the human hatcher's impatience and curiosity at cost to the potential chick.
- To check egg "freshness" for eating eggs
- To check for life in hatching eggs that are in lockdown but aren't hatched or pipped
There is no value in doing the float test for either reason.
It does not tell you whether an egg is "fresh". Whether the egg floats or sinks tells you nothing about whether or not it is a good or bad egg for eating, all it tells you is how big the air cell is. Eggs do get larger air cells the further they are from being laid, but there's also variablity from the thickness and porosity of the egg shell as well as the humidity of the environment. Less humid environments equal more moisture loss equal larger air cells developing faster. An egg can have a large air cell and still be completely edible with no significant difference in taste.
What the float test does do is destroy the protective biofilm "bloom" on the outside of the egg meant to keep bacteria out so the egg doesn't go bad, meaning that an egg that was put through the float test will now go bad faster than an egg that wasn't. If those eggs are meant for incubation, a washed egg is much less likely to successfully survive to lockdown.
Now how about for late hatchers? Why shouldn't you do the float test?
So, an egg that hasn't pipped or hatched isn't unaware of its outside environment. They are breathing through that porous shell, there is a constant gas exchange occurring; it's why coating the whole shell and blocking up those pores would quickly result in a dead egg.
When an egg with a live embryo is exposed to water coming through those pores, they can drown. And it does not take much for a chick still within its egg to drown- I've had chicks not hatch because only a couple drops of water pooled under their eggs and that was all it took.
Yes, if it's brief and the egg is dried afterward, they may survive it, but you essentially are waterboarding the baby chick inside that egg. They know that they're floating in water, and it's panic-inducing. That is what people are seeing when the egg bobs around. That does absolutely no favors to a weak or late-hatching/developing chick; in fact when they are startled and kicking in that egg, it's entirely possible for them to nick a vein in that struggle and at the very least, they are using up energy that could be put towards hatching.
It just gives them another hurdle to get over; yes, you can still have successful hatches after the float test but you made them struggle more than they had to. Washing away that bloom also makes them more susceptible to bacteria after being floated. By getting that egg wet, you've taken away their first line of defense and the chick itself has minimal immune system.
Floating them in cool water can also drop the egg temperature much more rapidly than exposure to same-temperature air, as water has a higher thermal conductivity than air, which is another shock to the potential chick that could weaken them unnecessarily.
There is nothing the float test can tell you that candling can't tell you, and candling isn't as damaging to the egg. Although you certainly don't need to, you can candle eggs you are planning to eat.
For candling for freshness, you can see bacterial growth as shadows in the egg, you can see cracks in the shell, and you can see the air cell size.
For candling hatching eggs, despite the egg being mostly dark at lockdown in a normally developing egg, you can still look for the correct coloring, shape, veins, and breathing. At that point in development, the chick has grown in size enough to likely bulge a bit into the air cell whether it's internally pipped or not, and you can watch that dark, rounded shape for subtle movement indicating breathing.
If you see active veins, movement, and/or breathing, it's best to just put the egg back in the incubator and let it continue developing. If you're really worried and feel like you need to assist somehow, you can do a "safety hole" not too much bigger than a pinprick to ensure the chick won't suffocate even if it's having trouble pipping. A small safety hole should not significantly affect the humidity inside the egg at normal lockdown moisture levels, but the hole being too big could dry out membranes, so use caution.
Careful observation with a decent light in a dark room can tell you all you need to know, and if you see no signs of life whatsoever but are still hesitant to give up on the egg, there are further actions you can take that will give you much more definitive answers.
If you're really unsure if it's worth continuing incubation and hatching is overdue, you can make a hole in the air cell just large enough to shine a light through and see inside. Again, I don't recommend doing so until the eggs are overdue. And it's best to keep the hole as small as you can while still being able to see inside.
If you see white membrane and it's moving rhythmically to the chick's breathing, you have a live egg and take no further action except possibly raising incubator humidity slightly to compensate for the hole you made.
If you see white membrane that's not moving, wet the membrane lightly with a slightly damp q-tip. If you see active veins, raise the humdity slightly and take no further action. If you see thin red lines that preciously were veins, they don't look active and you see no movement, the chick died recently.
If you see clear membrane, the egg died some time ago and the decomposition process has begun to dissolve the membrane.
The only time the float test is justified is with eggshells too thick or dark to see through whatsoever (most chicken eggs do not fall in this category, it's mostly more exotic species of fowl), and even then it should be a last resort done only when an egg is significantly overdue to pip. The float test has much more drawbacks than benefits, and in most cases, it only satisifies the human hatcher's impatience and curiosity at cost to the potential chick.
