Turn or don't turn with shipped eggs - an argument about science.

[ChickenCanoe]

I would like input from all the hatchers in the following thread that was posted in the emergencies forum.
https://www.backyardchickens.com/threads/detached-air-cell-bubbles-in-my-eggs.1392123/#post-22848225

 

[Kajoda929]

I'm curious too. Considering I lost all but two out of twenty-five hatching eggs, then another $43 with the promise of replacement eggs, only to be ignoted for a month.

 

[AquaDuck]

There are plenty of evidence that turning on day 3-7 is crucial for normal development of the fetus, dating back to the early 1900's. That's not to say that a non-turned egg can't possibly hatch, but that a developing chick might be malpositioned or damaged.

This article is unfortunately not available for free, but says
1. The physiological effects of egg turning during incubation are described. 2. There was a critical period for turning, from days 3 to 7 of incubation, which affected hatchability, embryo growth and utilisation of extra-embryonic fluids. 3. Failure to turn eggs retarded formation of allantoic and amniotic fluids, restricted alumen uptake and retarded growth of the embryo, but only after day 12 of incubation

Electrolyte and Water Balance of the Early Embryo: Effects of Egg Turning

This one about egg turning angles has a lot of good references.

I can't find anything specifically towards detatched air cells, but seeing as that in itself will reduce hatchability, personally I would do regular turning for those too.
(and would also, like you say in the other thread, not trust social media posts as facts)

 

[333113]

I wasn't in your original batch of responders in the link, but I will add my two cents here, which you can disregard.
I turn all eggs in the incubator, whether the air cell is detached or not. I do not have any experience that tells me an air cell can reattach.

In my opinion, which could be wrong or right, a detached air cell is a symptom of damage to the egg. I see it most often as a result of shipping, but I have seen detached air cells from eggs that were moved around a lot in the yard. (If Muscovy ducks could only read....!)

I think that sometimes the damage is only the detached, or partly-detached, or bubbled air cell, and sometimes there is also less-visible damage that disrupts the egg from developing. It may be shaking damage, or perhaps temperature damage. Slow yolk is another thing I look for, when you turn the egg while candling and the yolk is slow to shift within the egg.

I have had eggs with totally detached air cells go on to hatch, while eggs that travelled in the same package but with no visible damage failed to completely develop, and never hatched. I have to think there is more than one kind of damage. And if I would put those shipped eggs under a broody, I am pretty sure she would turn all of them, too. Nature selects for what works best.