Small air sacs - day 15

[tsid78]

Hi there,
I'm incubating 12 duck eggs for the first time. About 5/12 have small air sacs and we are on day 15 but the others are fine. My humidity has been in the 40s which I thought was kind of low but apparently not as some of my eggs air sacs are still so small. I've been cooling and misting since about day 7. Any ideas? What can I do?

 

[Amiga]

I suggest you look for the thread

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

and post there - lots of hatching going on.

@Lacrystol
@dotknott

 

[dotknott]

I'll need specifics how small is small? Compared to the ones that aren't small?
Have they grown at all?
Have you been weighing the eggs too?

In my last batch there were definitely some eggs that sported larger air cells than others, and even up to the end one or two that I worried about.

 

[tsid78]

Hi dotknott,
2/3 of the eggs are where they should be for day 14. 1/3 of them are at day 7 sizes. They've grown a bit but not much compared to the others. I don't know what to do humidity wise. I've been keeping it around 30 the past few days but still mist them. Do I go dry or go up to 55 humidity?

 

[dotknott]

Drier will increase the air cell size. You can try keeping it at 30 with no misting. See if they start increasing. Try that for a few days, then start misting again periodically.

I would worry about accelerating the ones that aren't behind too much though.

 

[Lacrystol]

Decrease the misting, only do it once a week