How do cage hens lay ..?

[jayjaymozza]

This may sound daft but it's been bugging me for days since I watched a documentary about caged hens, my question is how do they constantly lay ..?

I though chickens need to not be stressed, happy, healthy, well fed etc to lay ?
Surely to god these caged hens aren't happy?

 

[ChickenCanoe]

They can't help themselves. They've been bred to ovulate about every 26 hours under the right conditions.
They're fed optimal nutrition, They have constant clean fresh water. They are on a lighting program that stimulates lay. Most are kept at an ideal temperature with forced air ventilation. Other than not having privacy, dust baths, exposure to sunlight and space to spread their wings, they have a perfect life.