How are Chicken Eggs Fertilized

Chicken eggs are among the most popular food items due to their nutritional value. Bird eggs have been a part of human diet since the prehistoric period. Even though the eggs of various birds and animals are consumed by people in different parts of the world, chicken eggs are the most common and the popular one. According to some studies, six billion 12-packs of eggs are consumed every year in the United States alone. This figure shows the demand for this favorite food item from the farm, which is rich in proteins, vitamins and minerals. Each egg contains sufficient nutrition, meant for the developing chick, in case of fertilization.

Are Table Eggs Fertilized?

All are aware of the fact that chicks can be developed from fertilized chicken eggs only. Usually, a hen starts laying eggs from the age of three months at an average of five eggs a week. In order to get the eggs fertilized, the hen has to mate with a rooster. Otherwise, the eggs, laid by the hen will be unfertilized. Most of the eggs we buy from the store are unfertilized, as many poultry farms do not have the roosters to facilitate mating. Only when there is a demand for fertilized chicken eggs, or when they (poultry owners) need a new batch of egg-laying hens, that they search for a rooster. In short, you may not be able to hatch chicks by incubating chicken eggs, as there is no guarantee that such eggs are fertilized or not. Let us take a look at how are chicken eggs fertilized.

How are Chicken Eggs Fertilized?

The natural mating season of chickens start from spring, when the days start getting longer. The males, called roosters, have reproductive organs known as testes, which produce sperm, which are transferred to the sperm sacs, through tube-like structures called vas deferens. It takes only thirty seconds for the roosters to deposit sperm in the reproductive tract of the hens, called the oviduct. The sperm that leave the body of the rooster through an opening called cloaca, enters the oviduct of the female and travel through the various parts of the reproductive organs to reach the infundibulum, a fennel-shaped organ. In this journey, which takes almost one week to reach the destination, these sperm pass through the shell gland of the hen, then isthmus and magnum, finally to reach infundibulum. Once inside the infundibulum, these sperm can remain live for one week or more, waiting for the eggs, which undergo the process of formation.

The eggs are formed as yolk, in the ovaries of the hen. This yolk, when released from the ovaries, travels to the infundibulum. If there are sperm in this funnel-shaped organ, the yolk will get fertilized. Once fertilized, the yolk passes through the same route, through which the sperm traveled to reach the infundibulum. The only difference is that the yolk travels in the reverse direction and completes its structure to form a proper egg, during the course of this journey. The yolk is surrounded by the egg white in the magnum, whereas the formation of the shell membrane starts in the isthmus. From there the yolk travels to the shell gland, where the shell formation is completed and the shell gets hardened. The egg is ready to be laid, which is usually done in the mornings. Once the fertilized egg is laid, the hen is ready to start with the formation of a new egg.

In short, hens can lay eggs even without a rooster around, but such eggs will be unfertilized and cannot be incubated to develop a chick. You can even distinguish a fertilized chicken egg through the method of candling eggs. During candling, a fertilized egg can be differentiated with the presence of veins inside it. But it is always better to obtain fresh, fertilized chicken eggs, for the purpose of hatching chicken eggs.