Humidity. Research suggests MUCH higher

[Bicoastal]

In preparing for my next batch, I am researching humidity recommendations. Research sources like PubMed and various extension agencies suggest a MUCH higher humidity percentage than is typical here at BYC. How could there be such a large discrepancy?

"Optimal relative humidity was calculated to be 48 to 52%"
- British Poultry Science https://pubmed.ncbi.nlm.nih.gov/8062106/

"Keep relative humidity at 75 percent"
- Texas A&M Extension https://alec.unl.edu/documents/cde/2017/livestock-management/incubating-and-hatching-eggs-2017.pdf

"The relative humidity of the air within an incubator for the first 18 days should be able 60 percent"
- Penn State Extension https://extension.psu.edu/programs/...cience-of-incubation/humidity-and-ventilation

"Extensive research has shown that the optimum incubator temperature is 100°F when relative humidity is 60 percent."
-VA Tech Extension https://vtechworks.lib.vt.edu/bitstream/handle/10919/48447/2902-1090_pdf.pdf?sequence=1&isAllowed=y

"Relative humidity should be 60 to 65 percent for the first 18 days of incubation, and 70 percent for the last three days."
-Missouri Extension https://extension.missouri.edu/publications/g8353

 

[BarnyardChaos]

Maybe they're doing their own research and publishing those findings/recommendations, or just accessing different studies done by someone else?

Just like another member commented to me yesterday, I think it's all a crap shoot. There are so very many variables that it's hard to pin down the exact settings for the best outcome every time - like breed of chickens, size and condition of the eggs, hens' age and nutrition, ambient humidity and temperature, quirks of your own incubator(s), risk of contamination, turning method and schedule --- or I dunno maybe even background noise, lighting, or the way you hold your tongue when candling.

I've wondered if there's some trick of Mother Nature when a broody hen sits on her eggs, like can they hear or feel her heartbeat? Does her body contact do something an incubator can't do? Why can a broody hatch eggs when they're not turned evenly, or warm on one side and cold on the other, or exposed to whatever temps or humidity happen when she's off the nest? Why did I witness an egg hatching that had been kicked out of the nest and ignored in the cold for 2 whole days? And so on.

Like I said, it's a crap shoot. Take your best shot, and hope for the best outcome.

 

[BarnyardChaos]

Or sometimes when I get varying information, I'll do what some statisticians do: When faced with a range of different results, I'll throw out the highest and lowest figures from that range, then take an average of the rest.

 

[pipdzipdnreadytogo]

Experiments like these tend to be done in a strictly controlled environment. Out here in the real world, the environment is very rarely as controlled. The room where my incubators run, for example, very often swings a bit with the outside temperature. The humidity in that room may be higher or lower as well at any given time, depending on what's happening in the rest of the house and what the humidity is like outside. The climate and elevation where I live differs from other parts of the country, and other parts of the world. All of these things can have an impact on what conditions are most ideal in your incubator. So yes, as the other responder said, you'll unfortunately have to try things out and figure out what works best where you live.

For the record, I cannot answer your poll as I genuinely have no idea what my incubation humidity is ever at. I don't even own a hygrometer for my incubators. All I do is maybe add a little water when I set eggs and then adjust the vents and the amount of water based on how the air cells look when I candle them later on. It started off as me deciding I just didn't want another number to worry about, and it worked out so well for me that I've done it that way ever since. Your mileage may vary!

 

[MGG]

Yes elevation definitely plays a factor, along with the elevation the breeders were kept at, the porosity of the eggs, the species of eggs, etc.
It varies for every one. I just go off of air cell size. If they look a bit big I add some more water, if they look a bit small I run drier for a few days or until they're back on track. You could also weigh your eggs to calculate exactly what it needs to be for you, but I've never done that. If I get sticky big chicks hatching I know it's running too high as well. Too low is always better than too high. Right now I'm hatching ducks and running 30-40% until lockdown. That's what I do for most everything. Though I do cool and mist once a day which raises humidity a lot for half an hour or so. I'm not convinced it does anything but I'm doing it anyway, since I've heard so many say they have better hatch rates doing it. I get better hatches than broodies in my incubators. I give broodies the less valuable eggs and incubate the valuable ones just to keep incubator space open.