We are on Day 1 of our eggs in the incubator. We are starting out with 13 eggs. The breed breakdown is:
- 6 Jersey Giants
- 3 Ameraucanas
- 2 Laced Brahmas
- 2 Barred Rocks
We purchased these eggs from a reputable breeder in Georgia and had them shipped. Immediately upon arrival, I carefully unpacked the eggs and got them into the awaiting incubator, which had already been running for several hours. (Read more about this in Egg Hatching 101: Eggs and Incubator Prep)
In this series, we are going to walk through the development of eggs in real time as it is happening in our incubator. For chickens, the total incubation time is 21 days. That is a short amount of time for a lot to happen inside an egg.
But first off, a little back tracking... did you know that a rooster can mate with a hen and, 24 hours later, nearly every egg she lays for up to two weeks could be fertile? Now that's efficiency on the rooster's part (haha). Another cool fact is that the embryo inside the egg can wait for up to 10 days before incubation begins. When you think about birds in nature, it makes perfect sense. A chicken will lay an egg once every 25-26 hours or so. When a hen decides she wants to raise chicks, she will lay an egg in her nest every day until she has reached her predetermined magic number of eggs. It might be one, it might be 8. Who knows. But once that number is reached, she will then sit on her eggs and incubation begins.
As you can see from the photo at the top of this post, there are several parts to an egg. In our previous post, Egg Hatching 101: Eggs and Incubator Prep, we briefly mentioned the air sac, or air cell, when talking about how to sit the eggs in the incubator. In the photo above, you can see the labeled air cell at the fatter end of the egg. When you put your eggs in the incubator pointy end down, this helps keep the air sac more stationary and more easily accessible for the future chick. During the incubation process in the next 21 days, this air cell will continue to increase as the egg loses moisture through its porous shell. Maintaining proper humidity in your incubator will prevent unnecessary premature moisture loss, which could cause problems for the embryo development.
Some people swear by checking the air cell size via candling to make sure the egg is moving along at the right pace. Candling is done by shining a bright light through an egg and observing the shadows that you can see through the shell. Of course, this is a bit tricky with dark colored eggs (including blue or green tinted eggs). Candling is also done to track the development of the embryo and as a way to check for undeveloping eggs that need to be culled.
But back to Day 1. A fertile egg will have a germinal disc, or blastoderm (remember that nifty word from high school biology class?) that looks like a white bullseye on the surface of the yolk. You can really only see this by breaking open the egg, which you don't want to do obviously. So to satisfy your curiously, here's some cute little photos for you:
Germinal disc on an UNFERTILIZED egg
Germinal disc on a FERTILE egg. Larger spot, bullseye appearance.
Sometimes they are more obvious and sometimes you might miss them. If the egg has been fertilized, this white spot will look more like a bullseye (as shown above).
So, assuming the egg is fertilized, and is now kick started into growing gear by the incubator, the following things are happening right now:
- 18 HOURS: The alimentary tract appears
- 19 HOURS: The brain crease begins to form
- 20 HOURS: Somites appear
- 21 HOURS: Brain and nervous system begin to form
- 22 HOURS: The head fold begins to form
- 23 HOURS: Blood islands appear
- 24 HOURS: The eyes begin to form
Unfortunately, none of this can be seen via candling. We'll do our first candling on day 3. But by the end of today, this is what the germinal disc will look like in our eggs:
Germinal disc photo credits: The University of Illinois
But don't worry, we won't crack them open to check.
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