Friday, April 8, 2011

Incubation--Candling, Humidity, and the Hatching Process

Newborn chick resting--Hatching is hard work!
Our hatching is project is 2/3 of the way to fluffy baby chicks!  I ended up bringing the incubator home from the classroom to candle them and because it was difficult to regulate their temperature and humidity there.  Checking them at 8 am and 4 pm when we drop off and pick up our daughter in her classroom meant that any slight temp increase or humidity decrease might not be noted for 16 hours, which could be enough of an issue to cause us to hatch malformed chicks, or have a bad hatch rate, which is a nice way of saying chicks have died in their shells. I definitely don't want that to happen, even more so when the class of children will be audience to the hatch, and I won't be there constantly when the chicks are emerging.  So I brought them home to ensure their optimal development, as much as possible, and also to candle them so that I can see who is developing and who may have already died or never began to develop during the incubation process.

Candling is the process by which light can be shined into a developing egg from outside, and the word comes from the old practice of using a candle to do so.  Candling is an amazing experience, especially for children.  Eggs are 100% boring from the outside for 21 days, until the first pip occurs and the hatching process starts--but getting a peek  with candling gives a glimpse into the fascinating goings-on inside.  Candling is the perfect way to get kids excited about the incubation process when their interest may be flagging!  Check out this video I found on you tube...

So I candled on day 13 and found that 11 of  the 12 blue eggs (some are pure Ameracaunas, some are EEs) were definitely developing--one was unclear.  I couldn't really see into the dark dark brown of the French Coppered Black Marans eggs, so we will err on the side of hope and assume they are fine until we see or smell differently.

From day 1--set day--to day 18, things need to stay pretty steady.   Eggs have to be turned (tilted in different ways a few times a day and stay "big end" up (an automatic turner makes this MUCH easier) and stay at a constant temp of 99.5 to 100.5. This reflects the constants that a mother hen setting would maintain with her clutch of eggs.  (Broodies do get up and off the eggs for up to a half hour at a time to eat and drink and use the bathroom, and fact that means eggs have evolved to maintain their internal temps for short periods so we can do things like candle them or, in a pinch, move them from one place to another--for example, if you lose power or a bator quits on you).  A good incubator mimics a broody hen much better than a cheap one, and relieves you from having to go all "mother hen" as you cluck over constantly shifting and (dreadfully!) spiking temps and humidity.
Hovabator Little Giant Incubator

Brinsea Eco 20--I love this bator.
I started with a Hovabator LG (Little Giant), which is the bator found at every feed store I have ever been in.  It's a styrofoam box and the plastic viewing window is very small, a couple inches square.  This year, for the schoolyard chickens project, I bought something I've been wanting for a couple years--a Brinsea, one of the best.  (Mine is the still economical Eco 20, which will hatch 24 hen eggs, and with the turner I got both for about $150).  It's a plastic housing, not styrofoam, and the whole top is clear plastic, which makes viewing, especially with kids, a pleasure.  This incubator has made me a very happy chicken charmer, because has maintained a great deal of stability (though 16 hours was still too long for me to feel comfortable with not being able to check it and add water or tweak temps if needed!)  best advice I got?  Get two thermometers, the best you can afford--glass with mercury is great--and check them against your home thermostat, which is usually pretty right on.  take note if they read lower or higher than your thermostat and each other, and mentally 'calibrate' them each time you take a reading.  It's not as hard to remember as you might think, especially if you have one that is pretty spot on.  One word of caution:  the plastic strip thermometers that come with incubators are often 5 degrees or more off--be careful!

Aquarium I put eggs into at lockdown for better viewing
You can see my setup from my last hatch to the left.  I was desperate for the kids to be able to see the whole hatch, so I retrofitted a 10-gallon aquarium and put the eggs in it from my Hovabator on day 18, as a hatcher.  I had trouble regulating the temp and humdity with such a large expanse of glass.  You can see I have a large container of water to help keep humidity at 75% and was still having trouble (surface area is the most important factor--shallow and wide is better than narrow and deep)/  Iused a sponge and an old clean dishcloth in the water to help.  It was an ok hatch rate--6 of 11 fertile eggs hatched.  My biggest gaffe with this was that it was November and I didn't realize the window in the kitchen was slightly open, and I forgot to wrap aluminum foil around it that night--those things together meant the heat lamp on top couldn't keep the temp high enough to sustain the hatch.  I woke to find the hatcher at 92 on the morning after six of the twelve birds had hatched.

Egg on far left has pipped
About'll find two schools of thought on what humidity should be.  Some folks recommend wet hatch--meaning 50-60% humidity until day 18--while others swear that will end with "drowning" chicks during the hatch.  "Dry hatch" means keeping humidity at or below 40% until lockdown, and only adding water to the bator when it goes below about 25%.  You'll find equally expert old-timers who are ADAMANT that their way is the way to go, because they've had hundreds of thousands of successful hatches that method.  Yet they've used opposite methods to reach their success.  After a ton of research into this puzzling phenomenon, I realized that the link between humidity and hatch rate is affected by a third variable--altitude.  Folks in Colorado and Northern California and Montana have the greatest success with wet hatch, while people where I live--in Arkansas, near the Missouri and Kansas and Oklahoma borders--at much lower altitudes, do better while using lower humidity levels during incubation.  What's right for you?  Talk to people who have successful hatches in your region, and do what they do--then tweak your results, which may vary from theirs due to your bator or your eggs.  I like to keep my eggs between 30% and 40% humidity until day 18, and I only add water when we get down to 25%.  How does one gauge humidity?  You need a hydrometer.  They sell them at Lowe's and Wal-mart with the thermometers.  Another word of caution--they are often off.  To tell by how much, there is a relatively easy hack.  Put 1/4 cup salt into 1/2 cup hot water and stir.  Place cup and hydrometer in sealed plastic bag or food container--lid must be airtight, and make sure the hydrometer isn't going to get wet.  After 8 hours, the gauge SHOULD read 75%.  If you are reading high or low, take note by how much--you know exactly how much to add or subtract each time you check it; almost as good as having a perfectly calibrated instrument.

Day 18 is lockdown day.   That's the day you turn off the automatic turner (or stop hand-turning the eggs) and bump humidity up to about 70-75%.  You do this by adding water to the reservoirs in the bator.  Putting a cloth or strip of thick cardboard in the reservoir will retain more moisture in the air for longer.  75% is ideal.  Eggs may begin to peep and/or rock anytime after that, and eventually the chick will peck through the inner air sac and make a small hole in the shell through which it will get its oxygen and rest for a while before attacking the shell in earnest, creating a "zip" around the egg at the boundary of the air sac until the top of the shell pops completely off and the chick makes its way out. (In the video below, you can see where I have penciled in the "zipline" the chick will crack open.  I knew where to draw it by candling and seeing the delineation of the air sac.  I did this when I took the eggs out of the turner for lockdown).

Look, don't touch, during hatching.
It's extremely, ridiculously important--the difficult to overstate kind of important--that you follow a few rules about lockdown.  One:  sit on your hands.  Two:  sit on your hands.  Three:  You get the picture!  Humidity levels drop rapidly when you open the lid to mess with the eggs or add water.  If a chick has pipped the tiny air hole in its egg and you don't notice it (very common when you have more than a few eggs hatching!) the humidity dropping can "shrink wrap" the baby, making the inner membrane stick to its body all over inside the egg, and making hatching extremely difficult without the help of a human.  And once a chick is in trouble due to shrink wrapping and you open the bator to help it, you've just increased the chances of another one or more chicks getting shrink wrapped too.  It is much, much better for everyone involved to let hatching happen naturally, without opening the lid.  Most birds that have to be helped out of their egg will have problems and you may end up having to euthanize them.  A crippled or malformed chick is better left inside the shell if it cannot make it out alone, in my opinion.  Children can accept that "that chick just didn't make it" when "that chick" is nothing more than a shell with a small hole in it.  Help it out and you have a cute but ailing, or a grotesque issue to deal with.  Not fun with kids.  Again, my mistakes can be avoided!  If you MUST open the bator for some reason during lockdown, do this.  Go into the smallest bathroom you have, and crank up the hot shower.  When the room is filled with steam, that's the least problematic time to open the lid.  You want the humidity to not drop below 75% when you do this--higher is ok.  


Hatching.  This is the exciting part!  (As you watch this video, please ignore my children fighting and or screaming, or me being ever so slightly crabby/frustrated about said fussing.  I don't know HOW other people manage to post videos without these "bonus" effects.)  It can be hard not to swoop in and get the new babies out of the wet, sometimes stinky bator at this point, but resist the urge--any opening during hatch (after the first chick has pipped) endangers them.    Baby chicks come equipped with the ability to stay in the hatcher for a couple days if needed while the others make their way out.  They absorb the last of the yolk sac at the end of the hatch process, and it gives them the nutrients needed.  This is how big hatcheries can ship boxes of live baby chicks--they are sent on the first day of life.  So try to leave them in the bator/hatcher as long as possible.  The little guy you saw hatching in the video can be seen here resting an hour or two later.  Soon the incubator was overtaken with the hatching noises and excitement of three chicks hatching at once, so his nap was especially cute. Within a day or two after the first egg hatches, all the birds will be out and will have puffed up super fluffy and cute.

Six healthy Black Java chicks

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