Laying Hen Mortality and Disease in Commercial Flocks

Disease and mortality in commercial laying hen flocks reflect systemic welfare challenges, with conditions including avian influenza, Mareks disease, and osteoporosis causing enormous suffering at scale.

Key Facts

Commercial laying hen flocks of 100,000 birds or more are common in industrial egg production
Osteoporosis affects a high proportion of high-production laying hens due to calcium demands of egg production
Bone fractures occur in a significant proportion of hens at slaughter, many sustained during the production period
Mareks disease vaccination is nearly universal but highly pathogenic strains continue to evolve
Avian influenza outbreaks have required culling of hundreds of millions of birds globally since 2021

Welfare Considerations

Laying hen welfare is challenged by the fundamental biological incompatibility between high egg production and skeletal health. The calcium demands of producing an egg daily strip bones of minerals, leading to osteoporosis and fractures that cause chronic pain in a high proportion of commercial hens. This is a genetics and management problem with welfare solutions: breeds selected for bone strength alongside production, calcium supplementation, and adequate exercise can reduce but not eliminate this harm. Avian influenza culls represent an additional welfare layer — the method of culling, frequently ventilation shutdown which causes heat stroke, is itself a welfare emergency that the industry has been slow to address.

What You Can Do

Support research into laying hen breeds with better bone health alongside production levels
Advocate for humane culling methods in avian influenza outbreak response
Choose eggs from producers with breed diversity and welfare monitoring programmes
Back regulatory requirements for bone health monitoring in commercial laying flocks