How to know if your Eggs are Fertile?
The easiest way to tell if an egg is fertilized is called 'Candling the egg'. It is literally holding an egg up to a lit candle and make sure you don’t want to warm it but to see inside of it, then again we all have a Flash Light on all our so called Smart Phones that we all carry around. If the egg appears opaque, it is probably a fertilized egg, by opaque I mean you can't see through the egg or it is much cloudier than all of the other eggs.
You need to train your eye to catch this and the chances are most of us will fail in this exercise. This is what they all say and I personally find it difficult to see and unless you have the so called sophisticated gadgets if will be very difficult to do so. Let’s not go there for the moment as it’s not really worth it as there are many ways to find to introduce many Cocks to make your female eggs fertile and this is a much more cheaper way to do so.
As a side note, just because an egg is fertile doesn't mean it will become a chick. It has to be properly incubated naturally by a hen or Incubated artificially by An Incubator/Setter in order to develop into a Chick. After 5 days of Incubation in the Setter you can candle the egg again. You'll see that life has started to form and it will look like kind of red veins spreading throughout the egg.