Are you looking to grow chicks from your hens’ eggs and wondering if there is a way to tell they are fertile? Maybe you are looking to buy eggs to grow in an incubator and want to know they are fertile before paying for them. Or perhaps you have heard people say that supermarket eggs can sometimes be fertile.

There are lots of myths surrounding fertile chicken eggs and in this article, we sort out facts from fiction. We also look at the science of how chicken eggs are fertilized. So keep reading to have your questions about fertilized chicken eggs answered.

When Do You Get Fertile Eggs?

When Do You Get Fertile Eggs?

An egg will only have an embryo that develops into a chick if it is fertilized. Fertilization will only take place if the hen mates with a rooster before the egg has formed. If you are buying eggs from a smaller flock where the rooster mingles freely with the hens, every egg could be fertile.

However, it is not enough that the hen and rooster mate. Even a fertile egg will not develop into a chick unless it is kept at the right temperature either by the hen setting on it or by being put into an incubator.

Hens that are living in outdoor conditions will usually breed in the spring when the days get longer just like wild birds do. A rooster might mate with the hens throughout the whole year, but the hen will only incubate her eggs when she feels the conditions are right. When the hens are ready to incubate, they will become broody.

What Does the Rooster Do?

When a rooster wants to mate with a hen, it will perform a dance meant to get the hen interested. If the hen submits to mating the rooster mates with the hen for less than a minute.

During the mating, the rooster’s sperm leaves through the cloaca and travels through the hen’s oviduct and into her reproductive organs. It may take the sperm a week or even longer to reach the spot where they wait for the eggs to fertilize.

What Happens Inside the Hen?

A chick begins as an egg yolk in the hen’s ovary. When the yolk is released, it travels into a part of the reproductive system called the infundibulum, which is where the sperm are waiting.

The sperm will fertilize the egg, and the egg will travel out the same way the sperm came in. As it passes different parts of the reproductive system, it goes through various stages.

In the magnum, the egg white forms around the yolk and the shell membranes take shape inside the isthmus. Once the shell is formed and hard, the egg is ready for laying. When the egg is laid, the hen can start forming a new egg. There may be enough sperm left to fertilize eggs for another week or possibly a little longer.

Separating the Truth From the Myths

Separating the Truth From the Myths

Now we know the science behind chicken egg fertilization, let’s look at what is true about chicken eggs and what are popular myths.

Supermarket Eggs Can be Fertile – Myth (at Least Most of The Time)

As we know, a chicken egg will only be fertile if there were sperm present at the time it was formed. Supermarkets get their eggs from commercial chicken farms with no roosters around. Therefore, the eggs the hens produce will not be fertile. However, the farm may have a rooster around if they are looking to produce new egg-laying hens.

In that case, it is possible that, occasionally, some of these eggs could end up in a supermarket. But even then, you don’t need to worry about them growing into chicks as the eggs will have not been at the required temperature for the chicks to develop.

You Can Buy Fertilized Eggs – True

In most countries, you cannot buy fertilized chicken eggs for consumption. However, many chicken keepers sell them as hatching eggs. If you are looking to set up your own chicken coop, you might like to grow your chickens from the egg. Then, you would need to find a hatchery, either locally or online, and buy fertilized eggs from them.

Chickens Will Lay Eggs Without a Rooster – True

You don’t need a rooster for your chickens to lay eggs. You only need a rooster if you want fertilized eggs. Hens will lay eggs on their own once they have matured. This will usually be when they are between sixteen and twenty weeks old.

The exact age depends on the breed of your hen. The frequency of its egg-laying also varies based on its breed. As the chicken gets older, it will lay fewer eggs and will eventually stop laying them completely.

You Always Get Fertilized Eggs With a Rooster – Myth

There are no guarantees that you will get fertilized eggs that will develop into baby chicks if you have a rooster around. Even when the rooster mates with a hen, the result is not guaranteed. In some cases, the hen will eject the sperm or the sperm might fail to fertilize the eggs.

Roosters Are Not Always Fertile – True

You can still end up with unfertilized eggs when you have a rooster among your hens if it is not fertile. It is a much more common issue than many realize, with around 40% of roosters’ sperm being infertile.

This problem can affect both commercial chicken farmers as well as smaller backyard flocks. It is also possible that the rooster is not consistently fertile and will only succeed in fertilizing the hen occasionally.

If you are trying to get fertilized eggs and have no hatching success despite having a rooster in your flock, the problem could be your rooster. You may need to bring a new rooster into the flock or raise a separate, new flock with a new rooster.

You Should not Eat a Fertilized Egg – Myth

It is not true that you should not eat fertilized eggs or that they are not safe to eat. Fertilized eggs are safe to eat. For the cells inside the egg to develop, the egg needs to be kept at a certain temperature and humidity level after laying. Therefore, if the egg was not incubated, you would not be eating an undeveloped baby chick.

If you keep hens and there is a chance her eggs are fertilized and you want to eat them, collect the eggs regularly. This will stop a broody hen from incubating the eggs not meant for hatching. To ensure you only get unfertilized eggs, have a flock without a rooster.

Is it Possible to Tell if an Egg is Fertile?

To be able to tell fertilized from unfertilized eggs accurately before incubating would certainly make chicken keepers’ lives easier. There are some ways you can try to check if an egg is fertile before hatching.

Unfortunately, one method involves breaking the egg, and the other is far from accurate. If you would like to try, you can find the descriptions of the methods below.

Look for the Bullseye

Look for the Bullseye

The first method means sacrificing some of your eggs to look for the bullseye, which is the cluster of cells that would develop into a chick if the egg was incubated. While this process means potentially losing some fertilized eggs, the chances are there will be more fertile eggs in the same clutch that you can try hatching.

When you crack open the egg, you can see the blastodisc, which is a small white disc. In a fertilized egg, it will be circular with concentric circles, giving it the appearance of a bullseye. In an unfertilized egg, the blastodisc will be undeveloped with an uneven appearance and lack of rings or a distinctive center.


The other method you can try is candling. It will not damage the egg or the potential new chick inside but you should remember that it is not 100% accurate. To check your eggs using candling you need a dark room and a bright light source, such as a flashlight.

Once you are inside the dark room, hold an egg, which is three to four days old, against your light. The egg needs to be at least three days old because if you try candling newer eggs, you are unlikely to spot any signs of development.

Look for a tiny dark spot connecting veins inside the egg. This is the embryo. However, with this method, it is very easy to misinterpret what you see. In addition, a fertilized egg is still not a guarantee of hatching success as, unfortunately, things can still go wrong during the incubation period.


There are many common misconceptions about fertilized chicken eggs. We hope you now have a good understanding of what are facts and what is fiction regarding them. If you would like to ask anything else about fertilized chicken eggs, write your questions in the comments box.

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