Humidity for multiple hatches

[Gypsy07]

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Hi again! Chicks cannot drown before they start breathing air, just like babies cannot drown in the womb. They don't start breathing air until they are almost ready to hatch, and then they pip internally into the air sac at the fat end of the egg. They breathe that air for a while before they actually pip the hard shell of the egg. At the stage when they pip internally, if there is too much moisture still in the egg, then and only then will they drown. The cause of the excess moisture is humidity that was too high over the first 18 days of the incubation, but they absolutely cannot drown over the first 18 days.

If there is too much humidity in the egg you can attempt to compensate by using cartons. If the egg is lying flat and other chicks hatch first and kick it about, the chick could end up beak downwards and drowning in a tiny amount of liquid. Like the way babies can drown in a couple of inches of water. If it is just a small amount of excess moisture in the egg, keeping it upright and immobile can help the chick keep its beak above the liquid and avoid drowning. Does that explanation make sense?

Putting your other eggs in cartons between days 12-14 may still be useful though, as it could allow you to get in and out of the bator quicker when you're turning the eggs. Meaning less of a temperature and humidity drop each time you have to turn. I did that recently, and it more than halved the time it took me to turn the eggs. Just tip the whole carton at an angle with something under one side of it - six eggs turned in two seconds!

I have just done two staggered hatches where my humidity was up and down and up again depending on who was incubationg and who was ready for lockdown. I didn't have any drowned chicks and all my chicks that hatched are supremely healthy, but I *DID* have a higher than normal percentage of blood rings and early quitters, so the humidity fluctuations do seem to have had a negative effect on overall hatch rates...

 

[Three Cedars Silkies]

It is so simple to avoid this problem by having one incubator to incubate in and one to hatch in. Then the humidity is always ok for all the eggs.

 

[MuscovyMad]

Thanks gypsy07.

I think i get what you mean about the drowning. Is it just that too high a humidity means that less "egg juice" evaporates so when it comes to the internal pip the egg juice spills out into the air cell and the chick may drown if the other chicks decide to play eggy football resutling in the unhatched chick being beak down in egg juice.

If i hatch in egg cartons and there is too much "egg juice" will the chick just hatch out normal but be sitting in a wee bath?

Yet another question:

Should i let the humidity fall after the first chick has hatched to allow the other eggs (1 week behind) the chance to evaporate some more "egg juice"? Then raise it again at hatching? And they should be fine provided they are sitting up in egg cartons?

And yes two incubators would be great but with only 3 hens which will hopefully be broody alot (cochins) it's not really worth it.

 

[Gypsy07]

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Yes! That's it exactly.

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Yup, well, that's the idea. I'm not sure how well it works in practice though. If humidity has been just a bit high I'd imagine it would be more successful than if humidity had benn WAY too high throughout. But like I say I've never had soggy chicks so I can't say for sure.

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Well, that's what I did for my staggered hatches. I bumped my humidity for lockdown then after those eggs had hatched I removed the water trays altogether for a few days to compensate. Like I said, no drowned chicks, but a lower hatch rate. I wouldn't guarantee your chicks will all be fine, cause there's so much more than humidity that could affect them, but if they lose enough moisture overall, I can bet they won't drown in there.

You should have a look at Brinsea's website. I don't have a Brinsea bator (too pricey!) but I went to their site and downloaded for free their Incubation Guide that they give away with their bators. They seem to be a quality company with great products as far as I can tell, and I'd trust their information. Anyway, what they say about all this is that maintaining a steady humidity is of much less importance than maintaining a steady temperature. They say that while it's not ideal, quite wide fluctuations in humidity aren't too much of a big deal as long as the egg gets to lockdown having lost the correct amount of moisture. Losing it at a steady rate is not essential (though it is preferable). That's my words btw, but their information.

Eggs should lose 11-15% of their weight between days 1 and 18, and the easiest way to check that they are on course for that is by weighing them a couple of times through the incubation period. I have always weighed my eggs, mostly just cause I'm an OCD fusspot. But I do find it very helpful for checking humidity. The thing with eggs and incubating is, there is no one-size-fits-all ideal humidity the way there is an ideal temperature. What works well for one batch of eggs might be a disaster for another. Some eggs have thinner shells and lose moisture quicker than others. What works well for one person in one particular type of bator at one particular altitude and weather zone might not work elsewhere. There are loads more variables, those are just some.

So when I read people saying 'I always incubate at 35%, 45%, 55%, whatever, and I always get a 99% hatch rate...' all I ever think is "Well, that's what works for them!" If I was buying eggs from them, using the same kind of bator, and I lived in the same general area as them, I would definitely follow their figures. But anything apart from that, when I'm incubating, the only figure that I pay any attention to now is 11-15% moisture loss. That's what I'm aiming for.

 

[MuscovyMad]

So i went on to the brinsea website and printed off the booklet which made for very interesting reading. However i am now unsure as to the viability of my eggs as i read that you need to turn them atleast once a day to prevent them form sticking to the membrans and dying as embryos. And i havn't been doing this. I just shoved them big end up in a carton in a cupboard in the kitchen.

And with the egg thats currently in the incubator being one of her first and somebody saying they rarely hatch either. I'm thinking i might need to gather up some more eggs and try again. So the multiple hatches will be out the window. But atleast i have learnt ALOT.

P.s the incubator is round at a friends house. I decided that they should incubate the eggs as i get way too over excited and wouldn't be able to concentrate on my exams. I am going round to hers tomorrow though so i will candle the incubating egg and see if it's grown.

Fingers crossed and i'll keep you posted.