Why are commercial egg-laying hens usually slaughtered after two or three years?

In commercial poultry farming, egg-laying hens are typically slaughtered after two or three years because they have passed their peak production period.1

While chickens have a natural lifespan of six to eight years, intensive animal husbandry practices prioritize maximizing output. Through selective breeding, the industry has significantly increased the number of eggs a hen produces annually—rising from approximately 100 in 1910 to over 300 in the early 21st century. Once a hen's egg-laying rate declines after these initial years, it is no longer considered economically efficient to maintain the bird, leading to its removal from the flock.12

It is important to acknowledge that prioritizing production volume over the natural lifespan of an animal raises significant ethical concerns regarding animal welfare, as the drive for optimal yield often conflicts with the health and longevity of the animals involved.1