How Are Chicken Eggs Fertilized? – 13 Most Asked Questions

Hen looking after its eggs after successful fertilization

Although the process of how chicken eggs get fertilized may appear straightforward, its answer turns out to be quite fascinating. A lot of people are curious about this topic, which leads to a lot of follow-up questions.

This natural process is a blend of timing, biology, and the instinctive behaviors of chickens. It’s part of everyday life for chickens on farms and in backyards across the world.

Some of the most common questions people have about this amazing process will be answered in this article. We’ll uncover the secrets behind the start of a chick’s life in a way that’s easy to understand. Let’s begin!

How Do Chicken Eggs Get Fertilized?

Brown chicken eggs up close

Chicken eggs get fertilized when a rooster mates with a hen. During mating, sperm is transferred from the rooster’s cloaca to the hen’s. The sperm then makes its way into the hen’s oviduct to fertilize an egg. This happens before the egg’s shell forms.

Chickens mate in a process called “treading,” where the rooster climbs onto the hen’s back to line up their cloacas together, which allows for the transfer of sperm.

This quick encounter, usually just a matter of seconds, is enough for the rooster to fertilize the hen.

Interestingly, hens have specialized glands inside their bodies that allow them to store sperm for around two weeks. Because of these glands, hens can still lay fertilized eggs for a while, even if a rooster isn’t around.

When a hen ovulates and lays an egg, the stored sperm is strategically released from the glands. The sperm can then fertilize the next egg in the oviduct, which doesn’t have a hard shell yet.

If you’ve ever wondered what chicken mating rituals actually look like, here’s a video to show you:

How Do Chickens Mate? (2)

What Is the Difference Between Fertilized and Unfertilized Eggs?

Fertilized and unfertilized eggs are practically the same except for one key factor: whether or not they contain male chicken sperm.

A fertilized egg contains sperm from a rooster, and it has the chance to grow into a baby chick. On the other hand, an unfertilized egg will never hatch and will always just be an egg.

When you look at these eggs or taste them, you won’t be able to tell the difference. They look the same, taste the same, and are both good for you to eat.

How Can You Tell If a Chicken Egg Is Fertilized?

Chicken egg during candling

To find out if a chicken egg is fertilized, you can use a simple method called “candling.” This involves shining a light through the egg to see what’s inside.

If you notice a spiderweb of veins or a tiny dark spot, it’s a baby chick starting to grow! But if it’s clear, the egg is likely unfertilized.

Another way to check is by looking at the egg’s yolk after cracking it open. A small white spot on the yolk, known as the germinal disc, indicates it might be fertilized.

If the spot is more pronounced and slightly irregular, it’s more likely to be a fertilized egg.

That said, these methods are not perfect. Identifying a fertilized egg can be tricky, and certainty is usually only achieved after a few days of incubation or when signs of development become more obvious.

Meanwhile, watch this video to learn how to candle your eggs:

When to Candle Chicken Eggs | What is a Red Ring?

What Does a Fertile Chicken Egg Look Like?

Fertile chicken egg appearance

On the outside, a fertile chicken egg looks just like any other egg. But once you crack it open, you’ll see the difference.

Every egg yolk has a small white spot on its surface, known as the germinal disc. This spot changes if the egg is fertilized.

Initially, the germinal disc holds a single female cell known as the blastodisc. When a sperm penetrates this cell during fertilization, the blastodisc turns into something called a blastoderm. It looks a bit like a bullseye.

So, by looking for this bullseye, you can tell if an egg is just an egg or if it has the chance to become a baby chicken.

What Is the “Red Spot” on the Yolk?

It’s a common belief that a red spot means the egg is fertilized, but that’s not true. This spot is actually a tiny drop of blood, and it happens when a small blood vessel in the hen’s ovary or oviduct breaks as the egg is forming.

Blood spots are natural and can happen in the egg-laying process. They’re safe to eat and don’t affect the egg’s nutritional value or taste. If the spot makes you feel uneasy, you can easily remove it before cooking.

Can a Hen Lay Fertilized Eggs Without a Rooster?

Hen inside its nesting box

A hen can lay eggs without a rooster, but these eggs won’t be fertilized. Hens will produce eggs regularly as part of their natural cycle, regardless of a rooster’s presence.

However, for an egg to be fertilized, a rooster must mate with the hen. Without a rooster, the eggs that a hen lays have no chance of developing into chicks. These are the eggs typically sold in stores.

How Do Chickens Lay Eggs Without a Rooster?

Chickens can lay eggs without a rooster because egg-laying is a natural part of a hen’s body cycle. Think of it like how women have a menstrual cycle.

Hens have a cycle that produces an egg roughly every 24 hours, and this happens with or without a rooster.

A rooster comes into the picture only if you want baby chicks. If there’s no rooster, the eggs laid by hens are unfertilized, which means they won’t hatch.

Will All Eggs Be Fertile After the Hen Has Mated With a Rooster?

Hen checking its eggs

After a hen has mated with a rooster, it can lay fertilized eggs for a period of time, but not indefinitely. Fertilization can start quickly, sometimes as soon as 27 hours after mating, but it also depends on timing.

If an egg comes too early or too late, it might miss the chance to be fertilized.

A hen’s body is equipped to store sperm for up to two weeks. This sperm storage means that hens can consistently lay fertilized eggs during this window.

However, various factors like the hen’s health, the rooster’s fertility, and the timing of the egg’s release can affect whether an egg gets fertilized.

So, while a hen can start laying fertile eggs shortly after mating, it’s not always a sure thing. It’s a mix of precise timing and biological chance that determines if each egg is fertile.

What Does a Hen Do With an Unfertilized Egg?

Hens can’t tell if an egg is fertilized or not. If a hen is not broody, it will simply lay the egg and move on. However, some hens just have the natural urge to nest and warm their eggs.

In these cases, they might try to hatch the egg by sitting on it. After some time, most hens will give up and leave the egg if it doesn’t hatch. However, others might continue to sit on the egg in hope.

This is why farmers often collect eggs regularly to avoid confusion and ensure the hens continue laying.

How Long Does It Take for a Fertilized Egg to Hatch?

Egg hatching up close

A fertilized chicken egg takes about 21 days to hatch. The egg needs to stay warm the whole time, which a hen or an incubator can do.

As someone who’s had lots of experience hatching chicken eggs, I learned the importance of patience and attention to detail. Carefully monitoring temperature and humidity was essential for success.

By maintaining the right humidity, chicks could easily break through their shells when it’s time to hatch.

I’d also turn the eggs three times daily to prevent the embryos from sticking to the shell. This is something a mother hen does naturally.

After three weeks, if all goes well, you’ll see the egg start to crack, and a new chick will emerge.

Can You Eat Fertilized Chicken Eggs?

Yes, you can eat fertilized chicken eggs. They’re just like unfertilized eggs in taste, nutrition, and cooking uses. The only difference is their potential to become chicks.

Fertilized eggs are safe to eat as long as they’re collected quickly and refrigerated. This stops any development and keeps them just like any other egg you’d eat.

Are the Chicken Eggs We Eat Fertilized?

White and brown eggs on white background

Most chicken eggs people eat are not fertilized. Most commercial egg farms raise hens without roosters, so the eggs these hens lay have no chance of being fertilized.

Fertilized eggs are more common in backyard flocks where roosters are present. So, when you crack open an egg from the grocery store, it’s most likely unfertilized.

How Do Fertilized Eggs Taste Compared to Unfertilized Eggs?

Fertilized eggs taste the same as unfertilized eggs. There’s no difference in flavor, texture, or nutritional value when they’re fresh.

The key factor in an egg’s taste is freshness, not fertilization. Both types of eggs are equally delicious and safe to eat when they’re properly stored and handled.

If fertilized eggs are collected quickly and kept cool, they remain just like any other egg in your fridge.

Now that you know the ins and outs of how chicken eggs are fertilized, what do you think? If you’ve got questions, stories, or something to add, feel free to leave them in the comments below.

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