Chicken eggs are fertilized through a process involving a rooster and a hen. Here's how it works:
- A rooster fertilizes the egg by mating with a hen, during which he transfers sperm into the hen's cloaca (the common exit and entry cavity for feces, urine, and eggs in birds).
- The hen can store sperm in her reproductive system's sperm storage glands for up to about two to three weeks.
- When an egg yolk (future egg) is released by the hen’s ovary, it travels through her oviduct. Before the shell forms around the egg, sperm stored in the hen's reproductive tract meet the egg yolk to fertilize it.
- Fertilization occurs inside the hen's oviduct around 24 hours before the egg is laid.
- The fertilized egg then continues to develop its shell in the oviduct and is laid by the hen.
- The fertilized egg contains a developing embryo and will hatch into a chick if incubated under the right conditions.
Hens can lay eggs without a rooster, but those eggs will not be fertilized and thus will not develop into chicks. A rooster's contribution is essential for fertilizing eggs that can hatch into chicks. The process is quite quick, and fertilized eggs typically start developing an embryo within about 25 hours after fertilization.
