How can you tell which eggs are fertilised and which are not ?

The eggs you eat at home don’t contain real chicks, so don’t worry about finding one in the egg you’re eating. “But don’t chickens come from eggs?”, we hear you ask. Yes, that’s absolutely true, but a chicken doesn’t hatch from every egg. This is because the hen’s egg has to be fertilised by the cock. The cock fertilises about 80% of the eggs. In other words, eight out of every ten eggs that a hen lays will have been fertilised. This number decreases as the cock gets older. He starts to tire out more quickly and doesn’t have the energy to fertilise as many as before.

It is not easy to tell if your egg has been fertilised. It takes about five days for the first signs to appear. You can tell by holding a light against the egg. If it looks quite dark inside there is good chance that the egg contains a growing chick. If it is light inside it hasn’t been fertilised.