Ever cracked open an egg and wondered if it could have become a chick? Maybe you’re hoping to hatch some baby chicks from your backyard flock, or perhaps you’re just curious about those eggs you collect each morning. Whatever your reason, figuring out if your chicken eggs are fertilized isn’t as complicated as you might think!
As someone who’s been raising chickens for years, I’ve had to learn the difference between fertilized and unfertilized eggs through plenty of trial and error. Trust me, there’s nothing more disappointing than waiting 21 days only to discover none of your eggs were fertile to begin with!
Let’s dive into the simple ways you can tell if those eggs your hens are laying have been fertilized by your rooster.
First Things First: You Need a Rooster!
Before we get into the nitty-gritty of egg fertility detection, let’s clear up something super important:
No rooster = No fertilized eggs Period
This might seem obvious to some, but I’ve met plenty of folks who were confused about this! Hens will lay eggs regardless of whether a rooster is present. Those eggs just won’t be fertilized without a rooster to mate with the hen.
If you don’t have a rooster in your flock, you can stop reading now – your eggs are definitely not fertilized! But if you do have a strutting gentleman among your ladies, let’s continue…
Method 1: Crack It Open (The Blastodisc vs. Blastoderm Method)
The easiest and most definitive way to tell if an egg is fertilized is simply to crack it open and look at the yolk. Of course, this method only works if you’re planning to eat the egg, not hatch it!
Here’s what to look for
The Germinal Disc Check
On every egg yolk, there’s a small white spot called the germinal disc This spot contains genetic material, and its appearance can tell you whether the egg is fertilized
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Unfertilized egg: The germinal disc (also called a blastodisc) is small and irregular. It just contains genetic material from the hen.
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Fertilized egg: The germinal disc is larger and has a distinctive “bullseye” appearance with a clear white outer ring. This is now called a blastoderm because it contains genetic material from both the hen AND the rooster.
I remember the first time I successfully identified a fertilized egg – that little bullseye pattern was so clear once I knew what to look for! But don’t worry if you don’t get it right away. It can take some practice to spot the difference.
Method 2: Candling (The Non-Destructive Approach)
If you’re hoping to hatch your eggs, breaking them open isn’t an option! That’s where candling comes in. Candling is basically shining a light through the egg in a dark room to see what’s going on inside.
Despite the name, please don’t use an actual candle – a small, bright flashlight works much better (and is way safer!).
When to Candle
You can’t tell if an egg is fertile immediately after it’s laid. The embryo needs time to develop before you’ll be able to see anything.
For best results:
- First candling: Day 7 of incubation
- Second candling: Day 14 of incubation
I’ve tried candling earlier than day 7, but usually just end up confused and uncertain. Trust me, waiting until day 7 will save you a lot of head-scratching!
How to Candle an Egg
- Find a dark room
- Hold your flashlight against the large end of the egg
- Look for these signs of fertility:
Day 7 fertile egg will show:
- Dark lines (blood vessels) spreading from the center
- A small dark spot (the developing embryo)
Day 14 fertile egg will show:
- Much more darkness overall as the embryo grows
- Possibly some visible features like eyes
- Less empty space as the chick develops
Infertile egg (at any stage):
- Will look clear
- You’ll see the yolk as a shadowy spot
- No blood vessels or embryo
I once spent an entire evening candling eggs with my daughter. We made it into a science project, and she was absolutely amazed to see the tiny developing chicks inside. It’s genuinely fascinating!
Method 3: Wait and See
This isn’t so much a method as it is… patience. If you’ve placed eggs under a broody hen or in an incubator, in about 21 days you’ll know for sure if they were fertilized – they’ll hatch!
While this isn’t very helpful for determining fertility beforehand, it’s worth mentioning because sometimes eggs that appeared fertile during candling don’t develop fully. Nature isn’t perfect, and not all fertilized eggs will successfully hatch into chicks.
Common Myths About Fertilized Eggs
There are so many misconceptions about fertilized eggs! Let me clear up a few:
Myth 1: Blood spots mean the egg is fertilized
NOPE! Blood spots in eggs are caused by a broken blood vessel during egg formation. They can appear in both fertilized and unfertilized eggs and have nothing to do with fertility.
Myth 2: Fertilized eggs taste different
FALSE! There is absolutely no difference in taste between fertilized and unfertilized eggs. If you blindfolded me and gave me one of each, I wouldn’t be able to tell which was which.
Myth 3: Fertilized eggs are more nutritious
WRONG AGAIN! The nutritional content is identical. A hen’s body doesn’t change how it creates the egg based on whether it’s fertilized or not.
Why Aren’t My Eggs Fertilized?
If you have a rooster but aren’t getting fertilized eggs, there could be several reasons:
- New rooster: He might need time to adjust to his surroundings and establish dominance (usually about a month).
- Rooster favorites: Some roosters play favorites and only mate with certain hens.
- Too many hens: One rooster can typically handle between 6-16 hens. If you have more, he might not be able to mate with all of them.
- Age factors: Very young or very old roosters might be less effective.
We had this problem last year with our Rhode Island Red rooster who only seemed interested in two of our Buff Orpingtons while completely ignoring our Barred Rocks. After separating his favorites for a while, he finally started paying attention to the other ladies!
Can You Eat Fertilized Eggs?
Absolutely! A freshly laid fertilized egg is perfectly safe and healthy to eat. The embryo is just a tiny collection of cells that hasn’t started developing yet.
Once you refrigerate the egg, all development stops completely. You could keep a fertilized egg in your fridge for weeks, and it would never develop into a chick.
The embryo only starts to develop when exposed to the right temperature (around 100°F) for several hours. So unless you’re intentionally incubating the egg, there’s no chance of finding a developing chick inside your breakfast!
Final Thoughts
Whether you’re hoping to expand your flock through hatching or just curious about the eggs your chickens are producing, knowing how to identify fertilized eggs is a useful skill for any chicken keeper.
I hope these methods help you in your chicken-keeping adventures! Remember, the candling method takes a bit of practice, so don’t get discouraged if you can’t tell right away. With time, you’ll become a pro at spotting those tiny developing embryos.
Do you have any tricks for telling if eggs are fertilized? Or maybe a funny story about your first time trying to candle eggs? Drop a comment below – I’d love to hear from you!
Note: This article is based on my personal experience raising chickens and information from reputable sources. Always consult with a poultry expert if you have specific concerns about your flock.
Do Chickens Need a Rooster to Lay Eggs?
My very first time hatching eggs was 4 years ago. I got these fertilized eggs from Alabama Silkies.
I get this question a few times a year. The answer is no! You don’t need a rooster for a hen to lay an egg. Hens will lay one egg every 24 hours all on their own. However, if you want to hatch out chicks, you do need a rooster.
To produce an egg, chickens need an average of 12-16 hours of light, adequate calcium and a good diet. The whole process of forming an egg inside a hen is absolutely incredible!
How Do Roosters Fertilize Eggs?
When a rooster and a hen engage in mating behavior, the rooster transfers sperm to the hen through a process called “cloacal contact.” This occurs when their cloacas, the common opening for reproductive and digestive tracts, make contact, allowing for the transfer of sperm from the male to the female.
Once inside the hen, the sperm can remain viable for several weeks, ready to fertilize any eggs the hen lays during that time. If an egg has been fertilized, the embryo begins to develop within it.
Its worth noting that the eggs we typically consume are not fertilized (from the grocery store or your coop as long as you dont have a rooster). However, its also perfectly safe to eat a fertilized egg, as long as theyre fresh and havent been incubated. In fact, fertilized eggs look and taste just like unfertilized ones (see the comparison below).
How to tell if your chicken eggs are fertile
FAQ
How do you know if a chicken egg is fertilized without cracking it?
To determine if a chicken egg is fertilized without cracking it, you must candle it, which involves shining a bright light through the egg in a dark room. After about four to seven days of incubation, a fertile egg will show signs of development, such as tiny blood vessels and a dark spot (the embryo’s eye), while an unfertilized egg will appear clear, with only the yolk visible.
How soon can you tell if a chicken egg has been fertilized?
You can tell if a chicken egg is fertilized and beginning to develop by candling it with a bright light after about 4-7 days of incubation. A fertilized egg will show a developing embryo as a dark spot with a network of red veins spreading outward. If you see a clear egg with just the yolk visible, it is unfertilized.
What does a fertilized egg look like in the shell?
A fertilized egg, when viewed by candling (shining a light through it), appears as a developing embryo with a dark spot and spider-like red veins after about 7 days of incubation, whereas an unfertilized egg will appear clear and show only the shadow of the yolk. Inside the shell, a freshly laid fertilized egg shows a larger, more distinct germinal disc (blastoderm) on the yolk with concentric rings, resembling a “bullseye,” compared to the unfertilized egg’s simple, dense white spot.
How can I tell if my egg gets fertilized?