What actually is the BEST humidity?

[Texashatching14]

There's always so many opinions surrounding the ideal incubation humidity. I am getting some silkies and coturnix in a few days and am trying to figure out how to get the best hatch. Thanks!

 

[ChickenCanoe]

There is a difference in porosity of all eggs. Not just between species but between breeds. The eggs have to lose a certain amount of weight from transpiration of moisture through said pores.
IMHO the best way to deal with humidity is by weighing the eggs before setting and at intervals through incubation. You don't have to weigh them all but chicken eggs need to lose about 13% weight during incubation or about 0.65% a day. Other species are pretty similar.
You can make a graph and track if they are losing enough or too much and adjust humidity accordingly.

 

[dheltzel]

I dry hatch (under 30% until lockdown) and jack the humidity way up (80% or higher) during lockdown. Some breeds give me close to 100% hatches this way, others do not. I don't think there is an "always works" answer to the humidity question.

If the eggs are washed, they may lose moisture faster, maybe the humidity should be raised.
If the eggs are dark (Marans, Welsummers, etc) the pigment may inhibit evaporation and indicate a lower humidity.

The final answer is that you need to see what level works for you to get the right amount of moisture loss during incubation. I have a wide range of air cell sizes in my eggs when they go into lockdown, but there is certainly an optimal size and it correlates to a 13% weight loss during the entire period. In the end, the RH is irrelevant to the embryos, only that they lose the correct amount of moisture to leave plenty of air for them to pip into and work with during hatch.

 

[scflock]

Check out this thread: https://www.backyardchickens.com/t/978237/she-said-he-said-whos-right-whos-wrong-no-one

We started this one just because you will get conflicting advice from everyone. Humidity will depend on your area, the type of incubator, the breed of chickens, etc...
No one person can tell you exactly what your settings need to be, but there really isn't a right or wrong. You just have to find out what works for you. The thread has a lot of good information, but there is a lot of ribbing and silliness, too, so read it with an open mind

 

[Drewnkat]

I dry hatch (under 30% until lockdown) and jack the humidity way up (80% or higher) during lockdown. Some breeds give me close to 100% hatches this way, others do not. I don't think there is an "always works" answer to the humidity question.

If the eggs are washed, they may lose moisture faster, maybe the humidity should be raised.
If the eggs are dark (Marans, Welsummers, etc) the pigment may inhibit evaporation and indicate a lower humidity.

The final answer is that you need to see what level works for you to get the right amount of moisture loss during incubation. I have a wide range of air cell sizes in my eggs when they go into lockdown, but there is certainly an optimal size and it correlates to a 13% weight loss during the entire period. In the end, the RH is irrelevant to the embryos, only that they lose the correct amount of moisture to leave plenty of air for them to pip into and work with during hatch.

x2

No ONE humidity level is going to be the perfect method for every situation. You have to monitor how your eggs are doing, and adjust to their needs.

I have some eggs that have extremely thick shells, and are impossible to candle due to the pigment (green shells, not marans). They do amazingly well with a low-humidity method, and I believe they would not do well being incubated at 45-50% humidity like most incubator manuals instruct.

Eggs that have more porous shells might lose too much moisture with lower humidity, because they have different needs.

I would personally find weighing the eggs every day too stressful, but each person has their own methods they prefer. I prefer to start out with humidity around 30-35%, candle and mark the air cells at day 7. If they're looking good, I keep the humidity in the same range. If not, adjust it. Check again at day 14, and adjust if needed.

 

[ChickenCanoe]

All the comments have been spot on.
On weighing, I don't recommend doing it every day, that would be a full time job. I usually weigh at 7-10 days and that will tell me if it has been too high or low so I can adjust.
If weights were way off, I'll weigh another time or two.
As dheltzel said, the embryos don't care so the humidity on a given day has little meaning.
Eggs hatched under a setting hen will undergo humidity swings like when it rains or gets arid.