Question about humidity and temperature

[RoosterJuice]

Hi there! I haven’t incubated chicken eggs in about 6 years and I’m getting back into it again. I wish I had made notes but here I am… I’m wondering if anyone can tell me if this is generally correct: From days 1-18 keep the temp at 99-100 and keep humidity at 35-55%. Then at day 18 keep the temp the same but raise the humidity to 60-70% and stop turning the eggs. (Forced air w/ egg turner).
Thank you in advance!

 

[Huntmaster]

Yes, sounds like your memory is pretty good. Just a suggestion, I don't know what incubator you use but most don't read temp and humidity very accurately and would suggest separate calibrated thermometer and hygrometer for more accurate readings. Good luck

 

[RoosterJuice]

Yes, sounds like your memory is pretty good. Just a suggestion, I don't know what incubator you use but most don't read temp and humidity very accurately and would suggest separate calibrated thermometer and hygrometer for more accurate readings. Good luck

Absolutely, I keep an Accurite inside for this reason. Incubators shouldn’t even come with thermometers! I wonder how many hatches they have ruined… Thanks for the feedback!

 

[Huntmaster]

Good luck again and don't be afraid to ask any questions if your memory has a lapse as mine seems to have a lot of lately.

 

[Ridgerunner]

From days 1-18 keep the temp at 99-100 and keep humidity at 35-55%. Then at day 18 keep the temp the same but raise the humidity to 60-70% and stop turning the eggs. (Forced air w/ egg turner).

Spot on. I personally don't worry about being that precise with humidity as there is a range that works. After experimentation my "best" humidity is in the 40% range but that is with the hygrometer I have. It could be off a bit. With your parameters you should get good hatches. Best of luck!

 

[RoosterJuice]

Spot on. I personally don't worry about being that precise with humidity as there is a range that works. After experimentation my "best" humidity is in the 40% range but that is with the hygrometer I have. It could be off a bit. With your parameters you should get good hatches. Best of luck!

Thank you for your response! I also agree that the humidity range is rather forgiving.

 

[daisycaratti]

Spot on. I personally don't worry about being that precise with humidity as there is a range that works. After experimentation my "best" humidity is in the 40% range but that is with the hygrometer I have. It could be off a bit. With your parameters you should get good hatches. Best of luck!

hey sorry to barge in on the post what do you mean exactly how there is a range that works can you tell me what you mean

thanks

 

[Ridgerunner]

hey sorry to barge in on the post what do you mean exactly how there is a range that works can you tell me what you mean

Never be afraid to barge in and ask questions. It's a public forum, open to everyone.

Each egg has an ideal humidity for hatching. It varies by each egg depending in how and how long it was stored before incubation started, how porous the egg is, how thick the shell is, the consistency of the "whites" inside the egg, and who knows what else. It's all about how much total moisture is lost through the porous shell by the time the egg hatches. As an example, if you store an egg in relatively dry conditions for two weeks before you start to incubate it that egg will have lost a lot of moisture before it goes in the incubator as compared to an egg that was just laid.

Nature did not set up the process where each egg has to lose a really precise amount of fluid so it can hatch. A hen may lay eggs for two weeks to gather a clutch before she starts incubating them. So nature arranged it so one egg can lose more moisture than another and both still hatch and be healthy.

There are limits. An egg that does not lose enough moisture may not be able to maneuver in the eggshell to pip, let alone hatch. If it does manage to hatch it may be soft and spongy, not as healthy as it could be though many of these can live and thrive. If the egg is too dry the membrane around the chicks may shrink and wrap it too tightly for it to be able to move to hatch. Or it can have other problems.

For different reasons each incubator can take more moisture out of the egg than others. Forced air versus still air. The temperature and moisture level of the air outside the incubator that gets drawn in has an effect. In commercial operations where they may have several different incubators of an identical make and model each one has to be tuned to the "best" humidity for it. If you move it to a different location in the same room you have to re-tune it.

It is not instantaneous humidity that is all that important during the incubation phase either. Since you are looking at total moisture lost it is more about average humidity over the entire incubation. That changes during lockdown. By the time you go into lockdown the egg should have lost enough moisture or very close to it. During lockdown you want to maintain a higher humidity so the membrane surrounding the chick does not dry out when it pips and shrink-wrap the chick. That's why you bump up the humidity during lockdown.

My goal when incubating is to get as many eggs to hatch as I can. After several hatches I determined my sweet spot was around 40% average humidity. I still got a lot of chicks to hatch at lower and higher average humidities. High 30's and mid 40's still gave pretty good hatches but around 40% seemed to be optimum for my incubator, my eggs, and my conditions. With 20 chicks per hatch the difference might be one chick, not a lot and not all caused by humidity levels. Some people do better in the lower 30's. Some do better in the upper 40's. We are all unique.