The debate about 'what came first - chicken or egg' is an old one. This debate is endless, which seems to have almost no conclusion or many confusing conclusions. However, the debate of fertilized vs. unfertilized chicken eggs is a simple one, which is based on facts that you yourself can check. There are many differences between fertilized and unfertilized chicken eggs right from their formation to their nutritional content. Let us look at these factors which distinguish fertilized and unfertilized chicken eggs in detail.

Formation of the Egg
This is the most basic difference between fertilized and unfertilized chicken eggs. Understanding this main difference will help you clear your doubts on these two types of eggs. Here is one important fact - 'a hen can keep laying eggs despite mating with the rooster'. So, a hen can go on laying eggs even if the rooster is not involved. These eggs are unfertilized eggs. This means these eggs will never hatch. But, when a rooster mates with a hen, then hen can go on laying fertilized eggs. A fertilized egg has a potential of hatching some day into a chick. However, a certain environment and care needs to be taken of this egg for it to hatch into a chick. The fertilized egg need to be kept at a certain warm temperature for it to hatch.

Distinguishing Both by Candling
Candling is the process which can help you distinguish between both the eggs without having to break them. For this process, a candler is used on the egg. The process is carried out in a dark room. Candler can be a small flashlight or any other source of light shone on the egg. Hold the egg at slanting angle so that you can observe its width. Turn it to the left and right, and view the contents present inside the egg. If an egg appears opaque to you, then it is a fertilized chicken egg. Sometimes development in the egg might not be seen even if it is a fertilized one, for this purpose, keep it for few days for incubation and then observe.

Distinguishing Both by Breaking Them
Another way to check if the egg is fertilized or not, is to break them open. Simply, break the egg and observe it in the center of the yolk. If you observe a white spot or a white ring in the egg yolk, (yellow part) then the egg is fertilized. If you don't see any white formation in the center of the egg yolk, then it is not a fertilized egg. Apart from this sign, a fertilized egg can also show tiny red lines running along the surface of the egg yolk. These signs show that the embryo is present in the egg.

Debate on Health Benefits
Many people say that a fertilized chicken egg is more healthy. However, this is not true as both types of eggs are healthy and have almost same nutritional value. Eggs are one of the healthiest food, and good for people of all ages. But, if you store any egg for long, then it will start to lose its protein content. Also, if fertilized eggs are stored in the fridge, then they will not hatch.

Debate on Vegetarian Egg
There is argument going on unfertilized egg being vegetarian. This is not entirely true. For an egg to be called a vegetarian egg, the hen should be given a completely vegetarian feed. Also, the egg should not be fertilized. This type of egg is called vegetarian. This type of egg doesn't have life in it so considered by many as vegetarian. Still many vegetarians refrain from eating such eggs.

I hope this article cleared your doubts on fertilized and unfertilized chicken eggs. So, next time you break an egg open you will know if the egg was a fertilized one or an unfertilized one.