I have Isbar chicken eggs in my incubator, set over the last few days. I candled the eggs (shining a bright light through the shell) to check for viability. There were a few good examples that I thought I would share.
This egg is not fertile. It is clear, without any signs of veins beginning to form. At over a week of incubation, if it were fertile, veins would be forming near the air cell at the big end of the egg.
This egg has incubated for four days. If you look closely near the air cell on the top left, you can just see pink veins beginning to form. This is a fertile egg with an embryo developing.
This egg was an egg that was shipped to me. It had a detached air sac, meaning the membrane had become detached from the shell. This egg was fertile and veining had begun. Eggs with detached membranes often start developing but quit before hatching. You can see the air sac, which should be located at the top of the big end of the egg, rotates as the egg is moved. It is no longer attached to the shell wall. The veins have broken down since the embryo died and they are no longer distinguishable.
This is the same egg, rotated to the side. Notice the air cell is on the side of the egg now.
This egg started developing but quit early in it’s incubation. The veins have consolidated into a ring, referred to as a bloodring, around the circumference of the egg.
The blood ring goes all the way around the egg.
This egg, set ten days ago, is developing well with easily visible veining.
- Egg candling is best done infrequently during incubation to prevent injury to the eggs. I candle at 5-7 days and on day 18 when turning the egg is stopped and the humidity is raised in preparation for hatch.
- Eggs should be out of the incubation just long enough to candle them. should be done with a strong flashlight with a small beam of light. You can see in the last photo I have a pony tail holder curled up between the egg and the flashlight to block leaking of light.
- Of course white eggs candle best with tinted eggs being more difficult. It may be beneficial with dark eggs to wait a bit longer for the first candling when a dark mass can be seen in an egg with an embryo developing.
- It seems like this would not need mentioning, but be careful when handling eggs for candling. It is very easy to drop tremor hit the flashlight against the shell cracking it. I say this because I have done both. Handle eggs with care!
- Equally ridiculous to mention is the need to put the eggs back in the incubator after candling and to put the incubator lid back on or close the door, depending on your incubator. Don’t ask me how I know this.
- Check the incubator temperature and humidity in the first hour after candling to make sure it has returned to normal.
Here is a little video of a chicken embryo rocking, rolling and kicking in the shell.
This is a black Isbar chick that hatched yesterday.