Uneven air sac growth advice?

[PetraStonegirl]

I made several rookie mistakes on day one, and one of them was that I didn’t weigh my eggs before incubating, and I’m paying for that now. I could use some more experienced advice again. I am on day 16 with three different breeds incubating and I have uneven air sac growth. I’m assuming it’s a result of different shell porosities. My question is what to do about it.

In these images, the green eggs in foreground both show a steady growth between the day 7 and day 14. However, the brown eggs in the background show no discernible growth at all. Granted they are fairly small eggs compared to the others in the incubator, but I don’t know if that has an impact. I’ve read here that it can be an issue during hatching if there hasn’t been enough fluid loss during incubation. The breed I haven’t shown has one egg with air sac growth and one without.

My incubator has been running steady at 99.5F and between 50%-53%rf, both measures calibrated. I have two days before lockdown in which to run at a lower humidity in an attempt to assist fluid loss, but I am not sure if I should, and if I should, what rf should I aim for.

 

[TheFatBlueCat]

I'll try to answer, but I am no incubation expert. I don't think it would cause you any serious issues to run at a lower humidity for the final two days before lockdown. This is what I would do if I were you. How large is your largest air cell? Are you sure that the eggs that have smaller air cells are still alive?

 

[Ridgerunner]

I’m assuming it’s a result of different shell porosities.

Porosity can affect how fast an individual egg loses moisture but it's not the only thing. Things like how thick or thin the whites are inside or maybe shell thickness. I'm sure there are others I can't think of right now. How and how long the egg is stored before you start incubating can make a difference. They can lose moisture before they go into the incubator, especially if kept in low humidity. The size of the eggs may make a difference, not sure.

Because of these differences there is no one perfect moisture loss you'll get for every egg in the incubator. Luckily nature gave us a relatively wide window that will work. It's still a window, there are limits, so what you should be aiming for is the best average for all the eggs.

My question is what to do about it.

I assume the reason you are marking the air cells is so you can make adjustments to humidity levels as you go. How do those marks compare to what you are aiming for at this time in the incubation? Is the average about where it should be or too little or too much? Have you candled to see which may have quit or not developed so you can discard them?

I am not sure if I should, and if I should, what rf should I aim for.

Make your decision on what you see. You only have a couple of days left. If you need to lose a lot of moisture I'd be fairly dramatic in how much I lowered the humidity before lockdown. At lockdown it is what it is.

 

[PetraStonegirl]

Porosity can affect how fast an individual egg loses moisture but it's not the only thing. Things like how thick or thin the whites are inside or maybe shell thickness. I'm sure there are others I can't think of right now. How and how long the egg is stored before you start incubating can make a difference. They can lose moisture before they go into the incubator, especially if kept in low humidity. The size of the eggs may make a difference, not sure.

Because of these differences there is no one perfect moisture loss you'll get for every egg in the incubator. Luckily nature gave us a relatively wide window that will work. It's still a window, there are limits, so what you should be aiming for is the best average for all the eggs.


I assume the reason you are marking the air cells is so you can make adjustments to humidity levels as you go. How do those marks compare to what you are aiming for at this time in the incubation? Is the average about where it should be or too little or too much? Have you candled to see which may have quit or not developed so you can discard them?



Make your decision on what you see. You only have a couple of days left. If you need to lose a lot of moisture I'd be fairly dramatic in how much I lowered the humidity before lockdown. At lockdown it is what it is.

Thank you so much for your detailed answer. I did a day 14 candling and all embryos were in motion and with healthy blood vessels visible near the air sac boundary.

The air sacs on half the eggs are about where I would expect them to be on day 14 (first picture). However, the air sacs for the other half are bang on where they were back on day 7, which was at an appropriate size for day 7 (second picture).

When I initially hadn’t received a response to this post, I went ahead and opened my vent all they way, which dropped my rh to between 43% and 45%. If I let my incubator (nurture right 360) run dry, the rh crashes down to 4%. I might be able to let it run dry and add a small, shallow tray of water that the turner can slide along in an empty egg slot, in order to get something in the 20s or 30s. What kind of drama would you consider to be a safe yet dramatic drop for the 36 hours I have remaining before lock down?

 

[PetraStonegirl]

I'll try to answer, but I am no incubation expert. I don't think it would cause you any serious issues to run at a lower humidity for the final two days before lockdown. This is what I would do if I were you. How large is your largest air cell? Are you sure that the eggs that have smaller air cells are still alive?

Definitely still alive and moving on day 14. I lowered the humidity, and am debating lowering it further. I’m about to recandle one of the small air sacs to see if 24 hours at lower humidity has had an effect.

 

[PetraStonegirl]

Even 24 hours at 43%-45% rh has had a noticeable effect! I just recandled the egg with the smallest air sac, and it’s looking much better!

 

[Tonyroo]

The air sac is constantly shrinking in varying degree each day up until the chick hatches. So you need to be careful doing what your doing.

 

[Ridgerunner]

opened my vent all they way, which dropped my rh to between 43% and 45%. What kind of drama would you consider to be a safe yet dramatic drop for the 36 hours I have remaining before lock down?

I'd go with the 43 to 45%. It is simple and easy to do. I don't consider it that low to start with. With the limited time left I don't think you're going to lose that much more moisture anyway no matter what you do. I'm kind of surprised it made that much of a difference in your short time span. Are you sure your candling technique was consistent?

 

[PetraStonegirl]

I'd go with the 43 to 45%. It is simple and easy to do. I don't consider it that low to start with. With the limited time left I don't think you're going to lose that much more moisture anyway no matter what you do. I'm kind of surprised it made that much of a difference in your short time span. Are you sure your candling technique was consistent?

I’m leaving it at the current 43%-45% then, until lockdown tomorrow evening. The candling technique has been consistent between the days. Illuminate brightly from the air sac end with 1200 lumen LED flashlight in darkroom, and run pencil line along the boundary.

However, I did just find out that sometime last night (first night at the lower humidity) the reservoir had run dry and was refilled by a family member before I woke up this morning. So, it had deviated seriously down to 4%, which means it had been below 40% for several hours at least. During pre-setting testing, this incubator took about 4 hours to run the reservoir dry and get that low, from the time the humidity first started to drop. Maybe that’s why there was so much movement in such a limited time. Not ideal, that’s for damn sure.

Thanks for your time and advice!