If you keep chickens or are curious about poultry farming, you might wonder how farmers know if a chicken egg is fertilized. This question is especially important for those who want to hatch chicks or simply understand the difference between eggs meant for eating and those that could develop into baby chickens. Let’s explore the simple and effective ways farmers and backyard chicken keepers identify fertilized eggs.
What Is a Fertilized Chicken Egg?
A fertilized egg is one that has been fertilized by a rooster before the hen lays it. Hens lay eggs whether or not a rooster is present, but only eggs fertilized by a rooster have the potential to develop into chicks. Fertilization happens during mating when the rooster transfers sperm to the hen through a process called a “cloacal kiss,” aligning their cloacae to pass sperm to the hen.
Without a rooster, all eggs will be unfertilized and cannot hatch. However, if a rooster is part of the flock, many eggs will be fertilized, especially if the ratio of hens to roosters is balanced.
How to Tell If an Egg Is Fertilized
1. Cracking the Egg and Checking the Germinal Spot
One of the oldest and easiest ways to check if an egg is fertilized is by cracking it open and examining the yolk. Inside every egg yolk, there is a small white spot called the germinal spot or blastodisc.
– Unfertilized eggs: The germinal spot appears as a small, solid white dot. It contains only the hen’s genetic material.
– Fertilized eggs: The germinal spot, called a blastoderm, looks like a bullseye or a target with a clear white ring around it. This spot contains genetic material from both the hen and the rooster and is the starting point of embryo development.
This method is straightforward but has a downside: cracking the egg means it cannot be used for incubation or hatching.
2. Candling the Egg
For those who want to hatch chicks and cannot crack the eggs, candling is the go-to method. Candling involves holding the egg up to a bright light in a dark room to see inside the shell.
– Around day 5 to 7 of incubation, fertilized eggs will show visible signs of embryo development such as veins or a dark spot inside the yolk.
– Unfertilized eggs will appear clear or show only the yolk without any veining or embryo signs.
Farmers and hatcheries use candling regularly to monitor embryo growth and remove any eggs that are not developing properly to avoid contamination or spoilage in the incubator.
3. Observing the Presence of a Rooster
A simple but essential factor is knowing whether a rooster is present in the flock. Without a rooster, eggs cannot be fertilized. If you have hens only, all eggs will be infertile. If a rooster is present, many eggs will be fertilized, especially if the flock size is small to medium.
4. Floating Test (Not for Fertilization)
While floating an egg in water can help determine if it is fresh or old, it does not indicate fertilization. Fresh eggs sink, while older eggs float due to air pockets inside. This test is useful for incubation but not for fertilization status.
Why Does It Matter?
Knowing whether an egg is fertilized is crucial for farmers who want to hatch chicks. Putting unfertilized eggs in an incubator wastes time and resources and can cause unpleasant odors if the eggs spoil. For those who just want eggs for eating, fertilization usually doesn’t affect taste or quality, especially if eggs are collected promptly after laying.
Tips for Farmers and Backyard Chicken Keepers
– If you want to hatch chicks, keep a rooster with your hens.
– Use candling after about a week of incubation to check embryo development.
– Crack open a few eggs before incubation to check the germinal spot if you want to be sure your eggs are fertilized.
– Collect eggs frequently to prevent accidental incubation by hens and to keep eggs fresh.
Farmers rely on these simple, time-tested methods to manage their flocks effectively and ensure successful hatching when desired.
Fertilized eggs can be identified by cracking them to see a bullseye germinal spot or by candling to observe embryo development after several days. Without a rooster, eggs will never be fertilized, so the presence of a rooster is the first clue. These methods help farmers decide which eggs to incubate and which to use for food.