Contrary to a popular myth that people who do not know much about chickens believe, female chickens, also called hens, do not need a rooster to lay eggs or to complete their lives.
A hen will have all the eggs she is going to have and will be laying them as long as it is alive or until she is out of eggs no matter if there is a rooster present or not. The number of eggs a hen on a New Zealand farm lays over its lifespan depends mostly on the breed and the individual chicken.
Hens lay most of their eggs during the first three years of their lives. After that, they number of eggs drops down very considerably.
What can’t happen without a rooster is the making of baby chickens. The eggs will not get fertilized and no babies will be hatched. Obviously, humans do not need fertilization to have eggs for breakfast.
The control of the egg cycle of a hen happens because of its hormones and rooster presence is again irrelevant. Also, fertilized eggs do not taste any differently neither do they have any more nutrition than unfertilized eggs.
Compared to other birds, chickens have a very simple mating process. The length of the process and courtship may vary a bit among individual chickens.
A young rooster may mate with several hens within a very short period of time, typically within a few minutes. Mating can also be spread out over a day. A rooster may try to mate even when he is infertile. Fertility in roosters drops significantly with age and cold weather also has a negative impact on it.
Hens usually lay eggs in the morning. During this time the hormones in the hens rise. A hen would look for a nest and lay the eggs.