Have you ever wondered how a hen can lay an egg every day? Why some eggs are brown and some eggs are white? How many days an egg takes to hatch?



Here are the answers to those questions and many more.



Hens and eggs

Hens will lay eggs whether or not they’ve ever seen a rooster. Roosters are necessary only for fertilization of eggs.

Hens will lay eggs whether or not they’ve ever seen a rooster. Roosters are necessary only for fertilization of eggs.

Hens will lay eggs whether or not they’ve ever seen a rooster. Roosters are necessary only for fertilization of eggs.

Most hens are productive layers for two years before declining in production, but some continue to lay eggs for several years.

Most hens are productive layers for two years before declining in production, but some continue to lay eggs for several years.

Most hens are productive layers for two years before declining in production, but some continue to lay eggs for several years.

Normal laying routines can be interrupted by molting, winter daylight shortage, temperature extremes, illness, poor nutrition, stress, or lack of fresh water. Hens usually return to normal laying habits when the disruption-causing factor ends or is corrected.

Normal laying routines can be interrupted by molting, winter daylight shortage, temperature extremes, illness, poor nutrition, stress, or lack of fresh water. Hens usually return to normal laying habits when the disruption-causing factor ends or is corrected.

Normal laying routines can be interrupted by molting, winter daylight shortage, temperature extremes, illness, poor nutrition, stress, or lack of fresh water. Hens usually return to normal laying habits when the disruption-causing factor ends or is corrected.

Some breeds lay eggs daily, some every other day, some once or twice a week.

Some breeds lay eggs daily, some every other day, some once or twice a week.

Some breeds lay eggs daily, some every other day, some once or twice a week.

Female chickens are called pullets for their first year or until they begin to lay eggs. For most breeds, around 20 weeks is a typical age for the first egg.

Female chickens are called pullets for their first year or until they begin to lay eggs. For most breeds, around 20 weeks is a typical age for the first egg.

Female chickens are called pullets for their first year or until they begin to lay eggs. For most breeds, around 20 weeks is a typical age for the first egg.

Egg development and laying process

Eggshell production drains calcium from the hen’s body. The comb, wattles, legs, and ear lobes will fade as the calcium leaches out. Calcium must be replenished through either feed containing calcium, supplements such as oyster shell, or high amounts of calcium in the soil of birds with outdoor access.

Eggshell production drains calcium from the hen’s body. The comb, wattles, legs, and ear lobes will fade as the calcium leaches out. Calcium must be replenished through either feed containing calcium, supplements such as oyster shell, or high amounts of calcium in the soil of birds with outdoor access.

Eggshell production drains calcium from the hen’s body. The comb, wattles, legs, and ear lobes will fade as the calcium leaches out. Calcium must be replenished through either feed containing calcium, supplements such as oyster shell, or high amounts of calcium in the soil of birds with outdoor access.

Hens don’t usually lay eggs in the dark, so once a hen’s laying cycle reaches dusk time, she will usually not lay till the following morning.

Hens don’t usually lay eggs in the dark, so once a hen’s laying cycle reaches dusk time, she will usually not lay till the following morning.

Hens don’t usually lay eggs in the dark, so once a hen’s laying cycle reaches dusk time, she will usually not lay till the following morning.

The typical interval between eggs laid is about 25 hours, so a hen that lays an egg every day will lay a bit later each day.

The typical interval between eggs laid is about 25 hours, so a hen that lays an egg every day will lay a bit later each day.

The typical interval between eggs laid is about 25 hours, so a hen that lays an egg every day will lay a bit later each day.

Although a hen has only one exterior opening (the cloaca or vent) for egg laying and elimination, eggs are not contaminated during the laying process. Two separate channels, the oviduct and the large intestine, open into the cloaca. As the egg nears the end of the oviduct, the intestinal opening is temporarily blocked off. The egg passes through the cloaca without contact with waste matter.

Although a hen has only one exterior opening (the cloaca or vent) for egg laying and elimination, eggs are not contaminated during the laying process. Two separate channels, the oviduct and the large intestine, open into the cloaca. As the egg nears the end of the oviduct, the intestinal opening is temporarily blocked off. The egg passes through the cloaca without contact with waste matter.

Although a hen has only one exterior opening (the cloaca or vent) for egg laying and elimination, eggs are not contaminated during the laying process. Two separate channels, the oviduct and the large intestine, open into the cloaca. As the egg nears the end of the oviduct, the intestinal opening is temporarily blocked off. The egg passes through the cloaca without contact with waste matter.

As a chick embryo develops in a fertilized egg, the yolk provides nourishment and the albumen cushions the embryo.

As a chick embryo develops in a fertilized egg, the yolk provides nourishment and the albumen cushions the embryo.

As a chick embryo develops in a fertilized egg, the yolk provides nourishment and the albumen cushions the embryo.

If sperm is present, the yolk will be fertilized before the albumen is deposited.

If sperm is present, the yolk will be fertilized before the albumen is deposited.

If sperm is present, the yolk will be fertilized before the albumen is deposited.

From the time an ovum leaves the ovary, it takes approximately 25 hours for the egg to reach the vent for laying. During that time period, the yolk will grow larger while being surrounded by albumen (egg white), wrapped in a membrane, and encased in a shell. Pigment is deposited on the shell as the last step of the egg production process.

From the time an ovum leaves the ovary, it takes approximately 25 hours for the egg to reach the vent for laying. During that time period, the yolk will grow larger while being surrounded by albumen (egg white), wrapped in a membrane, and encased in a shell. Pigment is deposited on the shell as the last step of the egg production process.

From the time an ovum leaves the ovary, it takes approximately 25 hours for the egg to reach the vent for laying. During that time period, the yolk will grow larger while being surrounded by albumen (egg white), wrapped in a membrane, and encased in a shell. Pigment is deposited on the shell as the last step of the egg production process.

At any given time a productive hen will have eggs of several stages within her reproductive system. The eggs most recently discharged from the ovary are just tiny yolks, and the eggs farther down the oviduct are progressively larger and more developed.

At any given time a productive hen will have eggs of several stages within her reproductive system. The eggs most recently discharged from the ovary are just tiny yolks, and the eggs farther down the oviduct are progressively larger and more developed.

At any given time a productive hen will have eggs of several stages within her reproductive system. The eggs most recently discharged from the ovary are just tiny yolks, and the eggs farther down the oviduct are progressively larger and more developed.

A female chick is born with thousands of tiny ova, which are undeveloped yolks. Once she reaches maturity, an ovum will be released into a canal called the oviduct and begin its journey of development.

A female chick is born with thousands of tiny ova, which are undeveloped yolks. Once she reaches maturity, an ovum will be released into a canal called the oviduct and begin its journey of development.

A female chick is born with thousands of tiny ova, which are undeveloped yolks. Once she reaches maturity, an ovum will be released into a canal called the oviduct and begin its journey of development.

Egg variations

While most eggs have a slight sheen to the shell, some breeds or individual hens tend to lay eggs with a chalkier texture.

While most eggs have a slight sheen to the shell, some breeds or individual hens tend to lay eggs with a chalkier texture.

While most eggs have a slight sheen to the shell, some breeds or individual hens tend to lay eggs with a chalkier texture.

The shell color intensity of eggs laid by one hen can vary from time to time, with an occasional darker or lighter eggshell.

The shell color intensity of eggs laid by one hen can vary from time to time, with an occasional darker or lighter eggshell.

The shell color intensity of eggs laid by one hen can vary from time to time, with an occasional darker or lighter eggshell.

Shell color is only “skin deep”-- the eggs inside are the same as eggs of other colors.

Shell color is only “skin deep”-- the eggs inside are the same as eggs of other colors.

Shell color is only “skin deep”-- the eggs inside are the same as eggs of other colors.

Egg size is dependent on breed, age, and weight of the hen. Larger chicken breeds tend to lay larger eggs; banty breeds lay small eggs. Older hens tend to lay larger eggs than younger hens.

Egg size is dependent on breed, age, and weight of the hen. Larger chicken breeds tend to lay larger eggs; banty breeds lay small eggs. Older hens tend to lay larger eggs than younger hens.

Egg size is dependent on breed, age, and weight of the hen. Larger chicken breeds tend to lay larger eggs; banty breeds lay small eggs. Older hens tend to lay larger eggs than younger hens.

Double yolkers may have a normal amount of egg white with two or more yolks. In the shell, the egg may be unusually large.

Double yolkers may have a normal amount of egg white with two or more yolks. In the shell, the egg may be unusually large.

Double yolkers may have a normal amount of egg white with two or more yolks. In the shell, the egg may be unusually large.

Double eggs or “egg in an egg” are created when an egg with a shell is encased by the next egg in the oviduct and a shell is produced over the outer egg as well.

Double eggs or “egg in an egg” are created when an egg with a shell is encased by the next egg in the oviduct and a shell is produced over the outer egg as well.

Double eggs or “egg in an egg” are created when an egg with a shell is encased by the next egg in the oviduct and a shell is produced over the outer egg as well.

Shell-less eggs are released before they have time to develop a shell. They may have membrane holding them together or just be loose yolk and white.

Shell-less eggs are released before they have time to develop a shell. They may have membrane holding them together or just be loose yolk and white.

Shell-less eggs are released before they have time to develop a shell. They may have membrane holding them together or just be loose yolk and white.

“Fart egg” and “oops egg” are terms for tiny eggs that quickly pass through the oviduct without reaching full size.

“Fart egg” and “oops egg” are terms for tiny eggs that quickly pass through the oviduct without reaching full size.

“Fart egg” and “oops egg” are terms for tiny eggs that quickly pass through the oviduct without reaching full size.

Pullet eggs--the first ones produced by each pullet--are smaller than the eggs that the same hen will produce as an older hen.

Pullet eggs--the first ones produced by each pullet--are smaller than the eggs that the same hen will produce as an older hen.

Pullet eggs--the first ones produced by each pullet--are smaller than the eggs that the same hen will produce as an older hen.

Young pullets often lay malformed eggs before getting established in a normal laying routine. Older hens may occasionally lay abnormal eggs due to age, stress, or illness.

Young pullets often lay malformed eggs before getting established in a normal laying routine. Older hens may occasionally lay abnormal eggs due to age, stress, or illness.

Young pullets often lay malformed eggs before getting established in a normal laying routine. Older hens may occasionally lay abnormal eggs due to age, stress, or illness.

Chicken-and-egg behavior

Most hens will lay eggs in the same nest box as flockmates, so it’s not necessary to have a nest box for each hen.

Some hens like to lay their eggs in private and others will join their sisters in the nest box. Often two or three hens will crowd into one box while another nest box remains empty.

Sometimes a hen will sit on previously laid eggs and add her egg to the clutch. Another might prefer to sit in another area and deposit one egg by itself.

Often a hen will sing “the egg song” before or after she lays an egg. Some will sing during the process of laying. It is a cheerful song that seems to be a proud announcement.

Chickens learn by example, so a fake or real egg left in a designated nest box may encourage hens to lay there instead of on the floor or outdoors.

Unconfined hens may lay eggs anywhere outdoors if they don’t want to return to the nest box. Sometimes a free-ranging hen will go missing and reappear weeks later with a parade of chicks.

Chickens like to eat eggs, even their own. An egg that gets accidentally broken will likely be eaten by one of the chickens. If you occasionally find pieces of shell or egg yolk in the nest box, it’s usually nothing to be concerned about.

Some chickens become habitual egg-eaters that break eggs open and eat them. An egg-eater should be culled from the flock if you wish to have eggs for the kitchen. Not only will that chicken continue to eat eggs, but others will learn from watching and you may end up with several egg-eaters.

Holes in eggs and cracked eggs do not necessarily mean there is an egg-eater in the flock. A hen can accidentally crack an egg in the nest when she sits down or adjusts the nest to lay her own egg. Sometimes curiosity or boredom leads a chicken to peck at an egg without the intention of eating it.

Chickens can be fed their own or other eggs either raw or cooked. Eggs provide protein and the calcium in the shell is beneficial for laying hens. A potato masher can be used to break boiled eggs into pieces of egg and shell.