Hatching question

[Clay In Iowa]

What causes chicks to give up between day 18 and hatch??

FYI
Incubation conditions day 1-18: 99.5 degrees +/- 0.2, Humidity 44% +/- 2% only auto turner.

Hatching conditions day 18-21+ 99.5 degrees +/- 0.3, humidity 64% +/- 3%.

I have 2 digital thermometers in each, the incubator and hatcher, and they have 24 hr high/low. The temps and humidity never varied for the above conditions and usually hovered around the middle of the reported temp and humidity.

I put 4 very active Ameraucanas in the hatcher on day 18. Today, day 23, I have one chick. I don't understand what could have gone wrong.

 

[Ryu]

I always go by wet bulb readings. 84-86 degrees wet bulb for incubating, 90-91 for hatching.

Looks like you are at about 81 degrees for incubating and 88.5 for hatching, that could be the cause for late hatch/late quitters.

How big are the air cells on day 18?

Most of my experience has been with still air incubators, but we have a Brinsea Ova easy that is forced air, and it seems like the wet bulb readings hold true with it.

Were they shipped eggs?

 

[Clay In Iowa]

Yep all shipped eggs and it's a forced air unit.

 

[Ryu]

Where is Wilton to Iowa City?

ETA: You're pretty close to me. I work at the U of I. My sis has a black Roo on Wheaton based Ameraucana hens (offspring would be black). One hen is laying a nice big blue egg (roo is from blue only line so eggs would be blue from this cross). I'm getting 100% hatch from this hen right now, I could ask if I could collect some for you.

 

[Clay In Iowa]

I'm actually 6 miles north of Durant (wilton addy).

Durant is 35 miles east of Iowa City on I-80.

 

[Ryu]

Let me know if you want me to try to get the eggs posted above for you.

Good luck hatching!