Hens lay eggs without roosters.
A hen does not need a rooster to lay an egg. Hens ovulate regularly, regardless of whether there is contact with a male or not. Most grocery store eggs come from hens that have never seen a rooster.
Physiology
A hen will produce and release eggs, with or without a rooster present. Dennis C. Chang, Ph.D., consultant at Clarion Healthcare Consulting, says, "Domestic chickens lay one egg every 26 to 28 hours, about one egg a day, for a period of 4 to 6 days. In between periods of egg laying, the hen rests."
Fertilization
If a hen lays an egg without a rooster fertilizing it, a chick will not develop. If an egg is fertilized, it will develop into a chick ready to hatch in 21 days. According to poultry specialist Dr. Jacquie Jacob atthe University of Minnesota, "If it is going to be fertilized, it has to be done first thing along the assembly line, before the egg white, shell membranes and shell are put down."
Nutrition
According to the American Egg Board, there is no nutritional difference between fertilized eggs and unfertilized eggs. Dr. Jacquie Jacob says, "There is no health or safety issues with eating fertilized eggs."
Significance
Many residential neighborhoods allow chickens to be kept in back yards, but there are city ordinances banning roosters because they are loud and can be a nuisance. Because roosters are not necessary for the production of eggs, people in communities that allow chickens can enjoy fresh eggs from a private flock of hens.