Low hatching temp for large eggs?

[LaurenRitz]

I'm going to close this out with the few observations I can make.

Through day 12, temperatures seem to be primarily environmental. By day 14 temperatures are creeping up and the first 100+ temperatures appeared on day 15. By day 16 most of the surviving eggs were well above the ambient temperatures, even with lowering the incubator temperature. Looking at the patterns, I suspect some of those eggs would now be well into the 101 degree range if I hadn't turned the temperature down.

The lighter, thinner shelled eggs didn't survive the temperature fluctuations early in the test, while those with heavier pigmentation came through without a problem. As far as I can tell, size was irrelevant in this.

I think it is important to note that while a broody completely covers the eggs, there is often a cooler surface underneath that might leach some of this heat. At what we think of as lockdown, she stops turning the eggs and that heat loss (if any) is allowed to have an effect.

I'll give you a hatch report in a few days. Let me know if you think I should turn the temperature down more.

 

[MysteryChicken]

I'm going to close this out with the few observations I can make.

Through day 12, temperatures seem to be primarily environmental. By day 14 temperatures are creeping up and the first 100+ temperatures appeared on day 15. By day 16 most of the surviving eggs were well above the ambient temperatures, even with lowering the incubator temperature. Looking at the patterns, I suspect some of those eggs would now be well into the 101 degree range if I hadn't turned the temperature down.

The lighter, thinner shelled eggs didn't survive the temperature fluctuations early in the test, while those with heavier pigmentation came through without a problem. As far as I can tell, size was irrelevant in this.

I think it is important to note that while a broody completely covers the eggs, there is often a cooler surface underneath that might leach some of this heat. At what we think of as lockdown, she stops turning the eggs and that heat loss (if any) is allowed to have an effect.

I'll give you a hatch report in a few days. Let me know if you think I should turn the temperature down more.

I think it's weird you're having this issue, even though I hatch eggs of different sizes, & colors successfully lowering the temperature at 18 days.

 

[LaurenRitz]

My guess is that it's perfectly normal, and most people don't notice because they're not keeping such close track. It makes perfect sense that the chicks would increase body temperature as they get closer to hatch. It's also very possible that the extra heat is needed for metabolic purposes.

I don't know that it's a problem. I've just never noticed before. It is nerve wracking, though.

 

[NatJ]

With the incubator temperature at 98.5 (both thermometers agree), egg temperatures are 99.7 and above. That's a lot of heat. I know internal temperatures will be even higher and I'm bracing to lose the whole batch. I'm debating whether to turn it down to 98.

I took two eggs out to the broody, since she can probably control the temperature a little better than I can.

You are aware that chicken body temperature is higher than incubation temperature, right?

Body temperature of an adult hen is between 105 and 107 degrees (source: lots of results from an internet search.)

Regarding day-old chicks specifically, I find this source saying their internal body temperature should be 104-105 degrees.
https://www.cobbgenetics.com/en_US/articles/caring-for-chicks-between-hatch-and-placement
Since that is one of the major producers of meat chickens, I would trust them to be accurate. They are dealing with large numbers of chicks, and they have a strong interest in keeping those chicks alive and growing until butchering time.

If the chicks are supposed to have a body temperature of 104+ degrees right after hatch, I would expect them to have a body temperature higher than the incubator temperature in the last part of incubation too (no real source for this, just thinking through the obvious: either their temperature takes a major jump just when they hatch, or it gets there gradually over the days preceding hatch.)

I can't imagine that it's that much different than other hatches, but measuring makes it more nerve wracking.

Probably true. What you don't know or think about, you can't worry about very much either.