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How To Tell If An Egg Is Fertilized?

Written by:
Reviewed by: Philip Calahan
How To Tell If An Egg Is Fertilized?

Are you an avid chicken keeper? Do you find yourself wondering if your fresh eggs are fertilized or not? Wonder no more! Knowing how to tell if an egg is fertilized can be an important factor in your breeding program. Even if you’re keeping chickens for their eggs, being able to tell if a fertilized egg has been laid can help ensure that you’re not surprised with a chick hatching in your coop. In this article, we’ll discuss some tried and true methods for identifying fertilized eggs, from candling techniques to the age of the egg. Whether you’re a seasoned breeder or a beginner, this guide will help you identify whether your eggs are fertilized or unfertilized.

1. Understanding the Basics of Egg Fertilization in Animals

Egg fertilization is a natural process that occurs in most animals, including birds, reptiles, and some mammals. Fertilization occurs when a sperm cell from a male animal joins with an egg cell from a female animal, resulting in the formation of a zygote, or a fertilized egg.

In most animals, fertilization occurs internally, where the male’s sperm is deposited inside the female’s reproductive tract. However, in some animals, such as reptiles and many birds, fertilization occurs externally, where the egg is fertilized outside the female’s body.

Fertilized eggs are essential for the survival and reproduction of many animals. When an egg is fertilized, it develops into an embryo, which eventually hatches into a baby animal. Understanding the basics of egg fertilization is crucial for pet owners who want to breed their animals or care for eggs that may be potentially fertilized.

How Does Fertilization Occur?

In most animals, fertilization occurs during the process of copulation, where the male’s sperm is transferred into the female’s reproductive tract through a specialized organ, such as a penis. Once inside the female’s tract, the sperm travels towards the egg, which is usually waiting in the female’s oviduct or uterus.

Once the sperm reaches the egg, it must penetrate the egg’s outer protective layer, called the zona pellucida, to reach the inside of the egg. Once inside, the sperm’s genetic material combines with the egg’s genetic material, resulting in the formation of a zygote.

Factors Affecting Fertilization

Several factors can affect fertilization, including the timing of copulation, the number and quality of sperm, and the health and receptivity of the female’s reproductive tract. Additionally, environmental factors such as temperature and humidity can also impact fertilization in some animals.

It’s essential to understand that not all eggs will be fertilized, even if the male and female animals are healthy and capable of breeding. Some eggs may not be viable or may not be properly positioned in the female’s reproductive tract for fertilization to occur. Pets owners interested in breeding their animals should seek guidance from a veterinarian or animal breeding expert to maximize the chances of successful fertilization and healthy offspring.

2. Visual Indicators to Look for in Fertilized Eggs

If you have a flock of hens and a rooster, chances are that you will get fertilized eggs from time to time. These eggs contain an embryo that, if incubated properly, can develop into a chick. But how can you tell if an egg is fertilized or not?

The first visual indicator to look for is the “bull’s-eye” or “blastodisc” on the yolk. This is a small, white spot that can be seen on the surface of the yolk. It is the point where the sperm entered the egg and fertilized it. This spot is not always easy to see, but if you hold the egg up to a bright light source and rotate it slowly, you may be able to spot it.

Another indicator to look for is the development of blood vessels. If an egg is fertilized, the embryo will begin to develop after a few days. As it grows, it will send out tiny blood vessels that will be visible through the eggshell. You can check for blood vessels by shining a bright flashlight on the egg in a dark room. Hold the flashlight against the large end of the egg and look for a network of veins.

It’s important to note that not all fertilized eggs will develop into healthy chicks. Some may die early on, while others may develop abnormalities or fail to hatch. If you’re not sure whether an egg is fertilized or not, you can always try incubating it and seeing what happens. But if you’re not interested in hatching chicks, you may want to dispose of any fertilized eggs that you come across.

Tip: Always wash your hands thoroughly after handling any eggs, fertilized or not, to avoid the risk of contamination.

3. The Importance of Candling and How to Do It Properly

Candling is an important process to identify whether an egg is fertilized or not. In this process, you use a bright light to illuminate the egg and observe the internal structure. Candling can be done using a variety of light sources, including candles, flashlights, or specialized torches.

Candling is useful for several reasons. Firstly, it can help you identify whether an egg is fertilized or not. This is important because fertilized eggs will hatch into chicks while unfertilized eggs, if not consumed, will eventually rot. Candling can also help you track the progress of the embryo from day-to-day, which is important if you are looking to hatch the egg.

To candle an egg, you must hold it up to the light while making sure that the light source is positioned behind the egg. Make sure that you hold the egg gently and avoid shaking it. You can either use a specialized candling light or simply hold a flashlight up to the egg. Observe the egg for visible cracks, blood spots, or other abnormalities. If the egg is fertilized, you will be able to see the developing embryo clearly. The embryo should look like a small, dark spot, with veins spreading out from it.

It’s important to note that candling must be done carefully and gently, as rough handling can damage the embryo and cause it to die. Done correctly, candling can be a fun and informative process that helps you understand more about the fascinating world of poultry.

4. Common Myths and Misconceptions About Fertilized Eggs

How to Tell if an Egg is Fertilized?

If you’re new to egg fertilization or haven’t been given the right information, it’s easy to fall prey to common myths surrounding fertilized eggs. Let’s debunk some of these myths and misconceptions:

Myth #1: All eggs in stores are fertilized.
This is false. Unfertilized eggs are the norm in stores as there is no rooster present in commercial egg production facilities. The industry standard is to keep hens separated from roosters to ensure that all eggs are unfertilized.

Myth #2: Fertilized eggs always hatch.
While fertilized eggs have the potential to hatch, there are several factors involved in successful hatching, like temperature, humidity, and proper incubation. Not all fertilized eggs will lead to successful hatching.

Myth #3: If you don’t have a rooster, your eggs can’t be fertilized.
Egg fertilization can only happen when a rooster mates with a hen. However, if you’ve had a rooster in the past, your hen may still lay fertilized eggs as the sperm can remain viable for several weeks.

By understanding common myths and misconceptions, you’ll have an accurate understanding of how to tell if an egg is fertilized, and how to properly care for fertilized eggs.

5. What to Do With Fertilized Eggs if You Don’t Want Them to Hatch

If you have fertilized eggs but you don’t want them to hatch, there are several options available. It’s important to note that simply discarding fertilized eggs is not a responsible option. Here are some ways to deal with fertilized eggs responsibly:

1. Eat Them

Fertilized eggs are perfectly safe to eat, and some people even prefer the taste of them. However, if you plan on eating the eggs, it’s important to do it early in the incubation process. The longer the eggs are incubated, the more the chick develops and the more difficult it becomes to distinguish between the yolk and the chick.

2. Donate Them

If you have extra fertilized eggs and don’t want to eat them, consider donating them to a local school or farm. Many schools have programs where they hatch chicks as part of their curriculum, and farms may be interested in using the eggs to hatch their own chicks.

3. Sell Them

If you have a large number of fertilized eggs, you could also consider selling them to other chicken keepers or hobbyists. Make sure to properly label the eggs as fertilized so that buyers know what they are getting.

Remember, it’s important to never discard fertilized eggs in the trash or to give them to predators like raccoons or opossums. These eggs can still develop into chicks, and disposing of them in this manner is not only irresponsible but can also attract unwanted animals to your property.

6. How to Care for Fertilized Eggs and Hatch Chicks at Home

Hatching chicks at home can be a rewarding experience for pet owners and farmers alike. However, to ensure successful hatching, proper care must be given to the fertilized eggs. Here are some tips on :

1. Incubation

The first step in caring for a fertilized egg is to incubate it properly. This can be done through a commercial incubator, or through natural incubation. If using a commercial incubator, it is important to follow the manufacturer’s instructions on temperature and humidity levels. Natural incubation involves placing the fertilized eggs in a nest, often covered by a brooding hen. In either case, it is important to keep the eggs at a consistent temperature and humidity level.

2. Turning

During incubation, it is important to turn the eggs regularly, usually every 6-8 hours. This can be done manually, or through an automatic egg turner. Turning the eggs ensures that the embryo inside does not stick to one side of the shell, which can result in physical deformities or even death.

3. Candling

After approximately one week of incubation, candling can be done to determine if the egg is viable. Candling involves holding a bright light against the egg to see inside. A fertile egg will have a visible embryo and blood vessels. If the egg is not fertile, it will appear clear.

4. Hatching

After approximately 21 days of incubation, the chicks should begin to hatch. It is important to not interfere with the hatching process, as the chick needs time to break free from the shell and absorb the yolk sac for nutrition. Once hatched, the chicks should have access to food and water.

By following these tips, pet owners and farmers can successfully care for fertilized eggs and hatch chicks at home. With patience and care, watching a chick hatch can be a rewarding experience.

People Also Ask

1. Can you tell if an egg is fertilized before it’s laid?

No, it is not possible to tell if an egg is fertilized before it’s laid. The only way to know if an egg is fertilized is to crack it open and look for the presence of a developing embryo.

2. What is the difference between a fertilized and unfertilized egg?

A fertilized egg has been joined by sperm and has the potential to develop into an embryo and hatch into a chick. An unfertilized egg has not been joined by sperm and will not develop into an embryo.

3. How long does it take for an egg to be fertilized?

After a hen mates with a rooster, it takes about 24 hours for the egg to be fertilized inside the hen’s body. The fertilized egg then takes about 21 days to develop into a chick and hatch.

4. Can you eat a fertilized egg?

Yes, you can eat a fertilized egg. The presence of a developing embryo does not affect the taste or nutritional value of the egg, and many people around the world regularly consume fertilized eggs as a delicacy.

5. What does a fertilized egg look like?

A fertilized egg will look the same as an unfertilized egg from the outside. However, when you crack open a fertilized egg, you may see a small white spot on the yolk called the blastodisc. This is where the developing embryo will begin to grow.


In conclusion, it is not possible to tell if an egg is fertilized before it’s laid. The only way to know for sure is to crack it open and look for the presence of a developing embryo. While there is no difference in taste between a fertilized and unfertilized egg, some people choose not to eat fertilized eggs due to personal beliefs or ethical concerns.

Addie Schumann

Addie Schumann

My life is a blend of rustic charm and digital innovation. As a dedicated blogger, I pour my passion into every article, crafting stories that resonate with my readers. My blog serves as a canvas for my thoughts on a variety of topics, aiming to inspire, inform, and engage. With every post, I strive to bring a piece of Jackson's tranquility and my vibrant personality into the bustling online world.

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