Why do chickens lay eggs?

A nest with a fresh chickens egg.

Chickens lay eggs to procreate, it is their way of producing the next generation of chickens. 

Laying eggs is how chickens would naturally produce the next generation and is purely for reproduction from the chickens point of view. We have adapted and controlled their natural behaviour to service our society, a bit like the Borg in star trek.

Below: The deep brown chestnut colour of the Marans eggs.

From the human point of view we find it useful to select birds which lay the most eggs in the shortest time and it is artificial selection and or selective breeding that produces the chickens we know today that seem to lay and egg a day.

The hen has no idea she is, in the vast majority of cases, laying an unfertilised egg.

Do all chickens lay eggs?

All female chickens or hens do lay eggs. There are a few conditions where a damaged ovary means they do not. Provided they are well fed and looked after they should lay normally.

All it takes is a farmer choosing the hen that lays the most eggs as the progenitor for the next generation.

Below: A pair of hens sharing a nest while they lay eggs.

Perhaps without realising it, humans have been genetic bio-engineers ever since the dawn of agriculture through selective breeding.

After many generations over the thousands of years that chickens have been domesticated they have laid more and more eggs per year as a result of humans selecting for this trait.

Why do chickens lay eggs and not chicks?

Producing a large clutch of eggs and then hatching them all out at the same time is a bulk processing solution to raising a family.

Below: A clutch of baby chicks is the result of laying eggs and incubating them.


Laying a clutch of eggs, incubating and hatching them is a sure fire way of producing a dozen or so chicks at the same time. Chickens are a prey food in the wild and these types of animals often have large amounts of young to make sure some reach adulthood.

This way they are all at the same stage of development at the same time. It is also a test to ensure the chicks are strong enough, Hatching is quite an intense process and weak chicks will not survive, this ensures survival of the fittest.

Below: The Barnevelder mother hen has a large brood of chicks ensuring some grow up.

If a chicken laid or produced a live chick instead of an egg she would only be able to have 3 or 4 babies a year. It takes 21 days to grow a baby chick so even if she had them in quick succession with a long breeding season she would struggle to maintain the flock.

Also if chickens produced live young they would all be a different stages of development and this really does not work as bigger chicks bully little ones all the time.

Does it hurt for a chickens to lay eggs?

And does it take time for them to get used to it? I have no way of knowing absolutely but I would say it does not. I have around 300 chickens and have seen a great many of them laying eggs over the decades and they seem very content when settled on a nest to lay.

It does take them a little while to settle into eggs laying and get used to it. The odd pullet produces eggs with blood streaks on when they first start so it's not without it's problems.

I've never heard one make any sort of noise that would indicate that they were in pain while laying an egg. After the egg Is laid, however, they will often squawk loudly.
The reverse is true and if they can't lay an egg it is very uncomfortable and distressing. The inability to pass an egg is called egg binding and it’s lethal to a hen. I’ve been blessed that so far in that I see this issue very rarely.

Below: This is a series of images with a goose laying an egg.

I had to move a flock recently and three hens who needed to lay were not able to. They had their beaks open and were panting and constantly moaning in a long load squawk they don’t usually use, signs of severe stress and pain. They do like a quiet and undisturbed spot for nest and disruption will cause them to hang onto an egg.

You will be pleased to know they settled straight back in in the new coop and produced their eggs in a few minutes.

If the egg is too large, chickens can prolapse, which means their insides pop out. There are a great many reasons for this, inadequate diet, the egg may not develop properly, Thin shelled or shell less eggs or the hen’s muscles may not be strong enough to push an egg out.

They can become egg bound and if the egg breaks inside of them, they often die. If the problem isn’t recognised, a second egg will collect inside and cause severe stress. Surgical intervention is then needed but it’s rarely successful.

Battery farm chickens that have been rescued from egg laying factories are often given regular injections or implants to stop the egg laying.

Birds are designed to lay eggs and after the first few are quite used to the process.