How do you tell if an egg is fertilized by candling?

Answered by Jeremy Urbaniak

When it comes to determining if an egg is fertilized by candling, there are a few key indicators to look out for. Candling is a process where you hold a light source, such as a flashlight, behind the egg to see its internal contents. This technique allows you to observe the development of an embryo within the egg.

To begin, find a dark room or dimly lit area where you can easily see the light passing through the eggshell. Hold the egg up to the light source, making sure to cup your hand around the light to prevent any external light from interfering with your observation.

If the egg is fertile, you should expect to see a dark spot around the middle of the egg, known as the blastoderm or germinal disc. This dark spot is the embryo, which is in the early stages of development. It may appear as a small dot or speck, often surrounded by a slightly lighter area.

In addition to the dark spot, you may also notice the presence of spider-like veins beginning to form around the blastoderm. These veins are the beginning of the circulatory system and indicate that the embryo is growing and developing.

On the other hand, if the egg is not fertilized, you will typically just see the shape of the yolk inside the egg, without any signs of an embryo or veins. The yolk will appear as a rounded, yellow mass, without any distinct features.

It’s important to note that candling does have its limitations. The visibility of the embryo and veins will vary depending on the stage of development and the age of the egg. In the early stages of development, it may be challenging to see the embryo clearly, while in later stages, the embryo will be more prominent.

It’s also worth mentioning that candling should be done within a specific timeframe after the egg has been laid. The earlier you candle the egg, the more difficult it may be to see any signs of development. Generally, candling is most effective between 5 to 7 days after incubation has begun.

Personal experiences can provide valuable insights into the candling process. For example, I remember candling a batch of eggs from my own backyard chickens. As I held each egg up to the light, I was able to observe the dark spot and delicate veins forming within the fertile eggs. It was a fascinating experience to witness the early stages of life within those eggs.

Candling is a useful method to determine if an egg is fertilized. By holding the egg up to a light source, you can observe the presence of a dark spot, indicating the presence of an embryo, as well as the formation of veins around it. If the egg is not fertilized, you will only see the yolk without any signs of development. Remember, the visibility of these indicators may vary depending on the age and stage of development of the egg.