A rooster does not need to be present for a hen to lay eggs. However, if a rooster is not present, then the eggs will not be fertilized and will never hatch.
The chicken is a bird, specifically a fowl. Like other birds, the chicken lays eggs to reproduce. According to writer David Sherman in "Tending Animals in the Global Village," the chicken has been domesticated by humans for thousands of years.
According to "A History of Food" by author Maguelonne Toussaint-Samat, chickens begin laying eggs at about 20 weeks and continue laying eggs until their death. They can live anywhere from five to 20 years, depending on conditions and health.
Chickens will lay eggs regardless of whether a rooster is present. A chicken will not hatch from the egg unless the egg was fertilized by a rooster. The rooster fertilizes the chicken through sexual reproduction similar to mammals and humans.
Use for Food
"Tending Animals in the Global Village" estimates that there are approximately 10 billion chickens in the world being used for meat or eggs.
Chickens produce eggs constantly and continue producing them without a rooster's presence. However, to keep up production, eggs must be removed daily if not several times a day. If eggs are left in the nest, the chicken will stop producing eggs and start nesting and laying on the eggs in the hopes of having them hatch.