Animals and Lifecycles - Lifecycle of a Chicken (Bird)

Adult female chickens are called hens. Adult males are called roosters. Baby chickens are called chicks.

Lifecycle of a chicken

Egg

When hens are about 6 months old they start producing eggs inside their bodies. Each egg begins as a soft yolk and then the white part forms around it. A soft shell grows around that to protect the whole egg. The shell hardens and the hen passes it out of her body. This is called laying an egg.

A hen may lay one egg a day, sometimes more. Some human beings keep hens and collect the eggs for food. Hens do not need to mate with roosters to produce eggs, but an egg needs to be fertilised by a rooster before a chick can develop.

Chick

When a rooster mates with a hen, sperm goes from his body into the hen’s body and fertilises the soft yolks inside her, one at a time. The white part forms around the first yolk, the soft shell grows and hardens and the egg grows bigger until it is laid by the hen. The same thing happens with the other soft yolks that have been fertilised.

Usually the hen lays one fertilised egg every 24 hours after mating. Inside each egg is a tiny embryo which is growing into a chick.

The hen uses her body to keep each egg warm for 21 days. The embryo needs food to grow and eats the soft yolk around it. The hen turns each egg so that the embryo won’t stick to the shell as it grows.

After 21 days a chick is ready to hatch. It pecks holes in the shell and pushes itself out. Its feathers are wet but they dry quickly and the chick can run about and feed itself within hours.

Lifecycle of a chicken part 2>>