People often have concerns regarding the eggs they eat, but not all the eggs that a hen lays are fertilized. Most of the eggs that are commercially available are unfertilized. Farm fresh eggs tend to have a higher percentage of fertilized chicken eggs. How to tell them apart is a simple trick which you will find out as you read on. The confusion between fertilized and unfertilized eggs will be cleared by the end of this article. Before we begin, one must know what exactly is a fertilized egg. A hen lays eggs irrespective of the presence of a rooster. The chicken eggs are only fertilized if the rooster has mated with the hen, this has to happen before the egg is formed. Therefore, any egg that a hen lays before mating is unfertilized while after mating is fertilized. The embryo of a fertile egg does not undergo any changes once it goes into the fridge. It is said that if a hen has mated once, then for an entire week, she will lay fertilized eggs. How to Identify Fertile Eggs Traditionally, farmers used to hold the egg up in candle light to spot the embryo and blood spots. These days, special lights are available for this purpose. Using these lights, one can look through the egg to see if it is fertilized. This is known as 'candling' eggs. During the candling of the eggs, a fertilized egg will appear opaque. Once the egg has been cracked open, a fertilized egg looks like any other unfertilized egg with the exception that the white circle in the egg yolk will be more pronounced, and the yolk will also have tiny red lines running all along its surface. Many people confuse the white stringy material in the egg known as 'chalazae' with the embryo, but this is present in all eggs to prevent the egg from breaking. If someone wants fertilized eggs for hatching, then it is best to get the eggs from a farm. The chances of getting fertilized egg is higher there because of the presence of a rooster. One would then need to know how to incubate chicken eggs. The chicken will hatch after approximately 21 days. If an egg doesn't hatch within 27 days, it is best to discard it. Consumption of Fertilized Chicken Eggs Many people wonder, if it is okay to eat a fertilized egg. Well, there is nothing wrong in eating a fertilized egg; moreover. once it's in the refrigerator, there is no growth of the embryo whatsoever. Eggs are highly nutritious foods. Some people do claim that fertilized eggs are more nutritious, but this is a highly debatable topic. Eggs do tend to lose their protein content the longer they are kept. So, you can say that the freshest eggs are the most nutritious. Now that you know most of the things about fertile chicken eggs, there is no need to worry about that egg in your plate. Most probably it is unfertilized, so go ahead, enjoy your egg, sunny side up! Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.