If you are planning to start hatching chickens on your own, you will need to know which eggs to incubate. The problem is that you can not tell just by looking at a fertile egg and comparing to an infertile egg. They look the exact same on the outside.
The first step to having fertile eggs is to have a rooster among your chickens. Eggs don’t just become fertilized on their own. A rooster is needed. You also only need 1 rooster per 7 to 10 hens. Any more than that and they will be fighting over your girls. However, just because you have a rooster does not mean that your eggs are going to be fertile.
Crack Open an Egg or Two
This may seem like a waste, but the most obvious way to see if an egg is fertile is to check for a small white spot on the yolk. You can do this just before you cook your eggs. (Yes, fertile eggs are just fine to eat) This spot will be on the yolk and about 4mm wide. Sometimes it also appears to have a halo around the white spot or look like a bulls-eye. It’s very subtle and probably not noticed if your not looking for it.
Once you start seeing this spot on your eggs, you can start taking these eggs and putting them in the incubator. You only need to check 1 or 2 before you know.
Candling Eggs to Check Fertility
Candling eggs or checking fertility with a flashlight can be done duing the incubation process. Ideally, you have already seen the white spot on the eggs from the same hen and have started incubating eggs from her. After about the 9th day of incubation, you can use a light source to check for fertility. This is what is referred to as candling the egg.
Some incubators actually have a candling setting on them but if yours doesn’t, take your egg into a dark room. Shine a bright light from the underside of the egg on the wider end. If the egg is fertile, then you should see a dark spot around the middle of the egg, with some spider-like veins beginning to form around it. If it is not fertile, it will look just like a normal egg with the yolk inside.
You can even try something like the egg candler I found on Amazon below:
You can candle the egg multiple times throughout incubation to make sure your egg is developing properly. If it’s not developing, you may want to get rid of it and use that space for a new egg.