Incubating Chicken Eggs – the First 17 Days

We discussed how to prepare for an incubation in this previous post.  Now we are going to go over the first 17 days and how to manage your incubation during that time.

Once the eggs are in the incubator it is important to monitor the temperature and humidity throughout the day (or at least twice a day) and keep it in the right range.  The recommended temperature for chicken eggs is 99.5, and the recommended humidity is 45-55% for the first 17 days.  Here at high altitude, hatching is more difficult.  We have found through trial and error and many many incubations that keeping the humidity lower here at high-altitude increases our success.  So we keep ours at 30-45% for the first 17 days.  Also, if you don’t have an automatic egg turner, you need to be rotating the eggs as well.

You can candle for fertility as early as day 4 or 5, but with the darker colored eggs and our green eggs I prefer to just wait until about day 7 to candle for fertility so that I can be very confidant of what I am seeing.

You can buy special candlers, but we just use a strong flashlight.

We take 12 eggs out of the incubator at a time, very carefully load them into an egg carton, and take them to a dark room where we can candle.  We work quickly so as not to let them get chilled.  The mama hen leaves the nest for a few minutes each day to eat, drink, and relieve herself, so it is not tragic for the eggs to come out of the incubator for candling.  But don’t dawdle because you don’t want them out for too long.  If you can’t get through 12 fast enough then only take out 6 at a time.

It is very difficult to photograph candling eggs, but Young Man helped me out and figured out how to get pretty good pics.  You likely will need to click on the pics so you can see them closer to see the details I discuss.

At seven days an infertile egg will look like this:

It has a lot of light coming through the whole thing and you can see the round yolk.  As you carefully roll it the yolk moves around quite a bit.

And a fertile egg will look like this:

It lets less light through and the darker portion is bigger than just the round yolk.  As you roll it it wants to stay put more than the yolk in an infertile one.  On lighter colored eggs you can even see some veins and the chick itself.  In the photos above you can see some of the veins, and the dark spot on the bottom right is the chick, in the first photo it isn’t there, and then in the second photo it is there.  It was moving around during the photos.

Remove any infertile eggs from your hatch so you don’t have rotten eggs in the incubator.  If you are not sure, err on the side of caution and leave them in, it will become much more obvious within the next week and you will be able to know for sure.  Sometimes it is helpful to get an egg from the fridge that you know is infertile and look at it so you can have a clear idea of what an infertile egg looks like.  If you do leave some questionable ones in the incubator, you should candle again at day 10 and/or day 14.

Another thing to look for is what we call “early deaths,” meaning the egg was fertile and began to grow, but then died very early in the process.  You can remove these too.  Again, err on the side of caution and leave them if you are not sure.

There are two main things to look for when looking for early deaths.  The most obvious one is the blood ring.  Be careful not to confuse veins with a blood ring.  Veins look like branching veins.  A blood ring is a clear ring of blood.  If you are not sure – leave them in the incubator.

This is what a blood ring looks like, you can see the chick (dark spot on right towards the top), and the blood ring very clearly in this one.  Another things that shows very clearly in this one is the air cell on the right:

The other thing that shows an early death is that the egg is cloudy and has brown streaks.  It will not have any branching veins.  This can be harder to see, so again I say if you are not sure, leave it in.  Here is a picture with the brown streaks.

You can candle again on day 10 and/or 14 and remove any infertiles and early deaths that you missed previously.  The healthy eggs will get darker and darker as the chick fills more and more of the egg, and it will be harder and harder to see anything except the air cell.

Day 17 is the last time that the eggs need to be candled.  You need to remove any obvious early deaths and leave all the rest.  There is not much to see in a Day 17 egg, all you should see is the air cell (which will be a lot bigger that it was originally) and most the rest of the egg should be dark.  There is sometimes a tiny area at the tip (opposite end of the air cell) where light can get through.

Once you have candled on day 17, it is time for lock down on day 18.  We will discuss lock-down and hatching in our next post.

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