How cold can a fertile egg get before it’s not fertile anymore

[bobshere]

Hi I’m planning on keeping a rooster for the winter in hopes to get fertilized eggs to hatch. If my hens lay eggs in subzero temperatures (-20) and I get them in the house same day will they still be fertile or would have they gotten to cold to hatch?

 

[Pyxis]

Depends on how long they're out there. We sometimes get to -20 here (Fahrenheit not Celcius) and if the eggs are collected quickly, they can still be hatched. But if they sit out there long enough that their internal temperature starts to dip below 59 F (the ideal storage temperature for hatching eggs) then chance of hatching starts to decrease. If they're out for too long in below freezing weather, they will of course actually freeze solid, at which point they are definitely no longer viable.

 

[Abby125]

Hi I’m planning on keeping a rooster for the winter in hopes to get fertilized eggs to hatch. If my hens lay eggs in subzero temperatures (-20) and I get them in the house same day will they still be fertile or would have they gotten to cold to hatch?

Most likely if you leave them out there for too long they won’t hatch but earlier this year my hen had a secret nest I didn’t know about so she was laying egg for about a month they were out there in like 4F almost all of them hatched good luck

 

[chickengeorgeto]

Once the interior contents of a fertile egg reaches 40 degrees Fahrenheit then that egg will DEFINATELY not hatch. Eggs that freeze solid will crack and break similar to the way a metal water pipe will freeze and burst. Air temperature and the temperature of the contents of the egg is not the same thing. This is especially true when the eggs are deposited on the ground.

 

[Shadrach]

You can keep fertile eggs refrigerated, 6 degrees centigrade is as low as I would risk.
I've stored eggs at such temperatures for a few days and had them hatch.
An egg that has frozen won't hatch.
Because the outside temperature is below freezing doesn't necessarily mean sheltered eggs in say a bed of straw are at the same temperature as @chickengeorgeto mentions.

 

[GaryDean26]

I have hatched eggs that were in the refrigerator (4-5 deg C). Frozen eggs are a no go though. Eggs that have been out in the nesting box when in is below freezing always were clear when candled at 4-7 days. If they get below 0 deg C you may get a few out of hundreds to develop but it really probably isn't worth it at that point. Studies indicate that you best results come from eggs stored at 10-12 deg C. I personally only hatch from March to May every year. I am far enough south than we don't get any freezes after the middle of March and the hens all start their laying season late in January to early in February. After May we start to see daytime highs over 37 deg F so we turn off the incubator for the year.

 

[Mosey2003]

Once the interior contents of a fertile egg reaches 40 degrees Fahrenheit then that egg will DEFINATELY not hatch. Eggs that freeze solid will crack and break similar to the way a metal water pipe will freeze and burst. Air temperature and the temperature of the contents of the egg is not the same thing. This is especially true when the eggs are deposited on the ground.

Hatchability decreases, but I don't think 40 degrees is accurate to say they definitely won't hatch. Many people have picked up a dozen eggs from the store and gotten a fair few to hatch, and they have been under 40 degrees for at least a week that way.