If the rooster is removed for any reason, a fertilized hen will remain so for up to four weeks. She stores the unused sperm in so called "sperm nests" located along the oviduct of the hen. Since she only produces one egg each 24 hours, she needs to retain the sperm to fertilize each new egg. Although catso is technically correct, it would be unusual for different eggs to be fertilized by different roosters in a short period of time... One rooster can service about 12 to 18 hens quite satisfactorily... This of course depends on the health, age and breed of the rooster...