Egg candling is the process where a person use a bright light to look inside an egg to see if there is an embryo inside of the egg. Egg candling allow for a person to determine if an egg is fertile or if the egg is infertile. Furthermore, egg candling is a tool that helps to increase the hatch rate of the eggs; by removing the dead egg from the incubator prior to them rotting and contaminating the other eggs inside of the incubator.
In order to candle an egg, a person must find a dark room and a bright light. By placing the blunt end of the egg against the light, a person can view the interior of the egg. On the first day of incubation, a fertile egg will appear mostly clearly inside the egg; the yolk inside of the egg is clear, but there is a small dot (the blastodisc) visible within the egg.
How to Candle Eggs
By the third day of incubation, a fertile egg will have red veins that appears within the egg; these red veins look like a spider web and indicate that the embryo is growing within the egg. By the seventh day of incubation, the embryo within the egg will appear as a dark shadow within the egg. Additionally, if the egg is rotated on the seventh day, the embryo may appear to be moving inside of the egg.
By candling the eggs early in the incubation process, a person can identify which eggs are clear (and thus, which may be dead) versus those that are likely to contain an embryo. Early identification of dead eggs allow those eggs to be removed from the incubator (to prevent them from smelling and transferring bacteria to the healthy eggs within the incubator). The air cell is the pocket of air that is present within the egg at the wide end of the egg.
The size of the air cell is an indicator of the humidity within the incubator. As the embryo develop within the egg, moisture leaves the egg. As a result of this loss of moisture, the air cell within the egg expand.
If the air cell within the egg is too small on the tenth day of incubation, the humidity within the incubator was too high; high humidity can lead to the chicks drowning when they emerge from the eggs. If the air cell is too large on the tenth day of incubation, the humidity within the incubator was too low; low humidity can lead to the embryo within the egg stick to the shell of the egg. The air cell within the egg will steadily expand during incubation; by day eighteen of incubation, the air cell may begin to appear wavy.
The wavy air cell within the egg is an indication that the chick have pierced the membrane within the egg to breathe. It is easy to identify if an egg is infertile or if the embryo within the egg has die. An infertile egg will appear clear throughout incubation; there will be no vein within the egg.
A dead egg may reveal a blood ring within the egg. Additionally, if the egg is a “late quitter,” there may be dark mass within the egg that have detached from the embryo. These dead eggs should be immediately removed from the incubator; should the eggs die within the incubator, they can explode and spread bacteria to the healthy eggs within the incubator.
The equipment that a person may use to candle eggs can impact the success of the process. LED candling is considered to be more better than using a flashlight from a persons phone. Additionally, white eggs are easier to candle than brown eggs.
This is due to the fact that the light can pass through the white shells of the eggs more easy than the brown shells. To candle brown eggs, a very bright light and a very dark room will be required. Additionally, a thermometer hygrometer can be used to monitor the humidity and temperature within the incubator, a pencil may be used to mark each egg to ensure they are rotated during incubation, and a gram scale can be used to determine the weight of each egg.
Additionally, like any activity that involve the eggs, it is important to wash your hands before you touch the eggs to ensure the health of the eggs, embryos, and chicks.