The Short Answer
The color of a chicken egg is determined by the breed of the hen that laid it. Chicken breeds with white earlobes lay white eggs, while breeds with red earlobes lay brown eggs. This is because the gene that codes for earlobe color also codes for egg color. So hens that inherit the dominant red earlobe gene will lay brown eggs, while hens that inherit the recessive white earlobe gene will lay white eggs. The egg’s shell color comes from pigments that are deposited as the egg develops in the oviduct. Brown egg layers put more pigment onto their eggs than white egg layers. But the interior quality and nutritional content of brown and white eggs are identical.
Earlobe Color Determines Egg Color
Chicken egg color is primarily determined by the breed and genetic makeup of the hen. Interestingly, the gene responsible for earlobe color in chickens also codes for egg color. This is why hens with white earlobes lay white-shelled eggs, while hens with red earlobes lay brown eggs.
In chickens, red earlobes are produced by a dominant gene, while white earlobes are produced by the recessive form of the gene. Hens that are homozygous dominant for the red earlobe gene (with two copies of the dominant red allele) will always have red earlobes and lay brown eggs. Hens that are homozygous recessive for the white earlobe gene (with two copies of the recessive white allele) will have white earlobes and lay white eggs.
Hens that are heterozygous, with one copy of each allele, will also have red earlobes and lay brown eggs because red is dominant over white. So the earlobe color (and in turn, egg color) comes down to the hen’s genetics. This is why certain breeds, like Rhode Island Reds, lay brown eggs, while others, like Leghorns, lay white eggs.
Pigments Produce Egg Color
The specific pigments that color the eggshell are called porphyrins. As the egg travels down the oviduct, cells deposit pigments onto the developing shell. Red-brown pigments called protoporphyrins produce the brown egg color. These pigments are secreted along with the calcium carbonate that makes up the eggshell.
Hens that lay brown eggs deposit much higher levels of protoporphyrins onto their eggs than hens that lay white eggs. White egg layers deposit only a small amount of pigment. The protoporphyrins are what make the brown eggshells darker and browner.
Without these pigments, an eggshell would be white due to the calcium carbonate. So it’s the special pigments that certain breeds deposit onto the shell that creates the brown color. The interior contents of brown and white eggs are nutritionally identical. Only the outer shells differ in color.
Breeds That Lay White Eggs
| Breed | Origins |
|---|---|
| Leghorns | Italy |
| Minorcas | Spain |
| Anconas | Italy |
| Andalusians | Spain |
| Catalanas | Spain |
| Hamburg | Holland |
| Lakenvelder | Germany |
| Campines | Belgium |
There are several chicken breeds that typically lay white-shelled eggs. The most common white egg layers are:
– Leghorns – Originated in Italy, known for excellent egg production
– Minorcas – Originally from Spain, lays very large white eggs
– Anconas – Another Italian breed that lays about 280 white eggs per year
– Andalusians – From Spain, small white eggs at a rate of about 175 per year
– Catalanas – White eggs from this Spanish breed
– Hamburg – Holland breed lays medium white eggs at a good rate
– Lakenvelder – Medium white eggs from this German breed
– Campines – Originated in Belgium, lays medium white eggs consistently
So Mediterranean breeds like Spanish, Italian, and Dutch chickens commonly lay white shelled eggs. The Leghorn is the most widespread white egg layer used in commercial egg production.
Breeds That Lay Brown Eggs
| Breed | Origins |
|---|---|
| Rhode Island Red | United States |
| Plymouth Rock | United States |
| Australorp | Australia |
| Orpington | United Kingdom |
| Barnevelder | Netherlands |
| Marans | France |
| Welsummer | Netherlands |
| Wyandotte | United States |
The breeds that typically lay brown eggs include:
– Rhode Island Red – Well-known American breed laying 250+ brown eggs per year
– Plymouth Rock – Another American breed that lays brown eggs regularly
– Australorp – Originated in Australia, lays about 250 large brown eggs annually
– Orpington – The popular British breed lays large brown eggs consistently
– Barnevelder – Medium brown eggs from this Dutch breed
– Marans – Dark chocolate brown eggs from this French breed
– Welsummer – Speckled brown eggs from this Dutch chicken
– Wyandotte – American breed best known for brown colored eggs
As you can see, many American and European breeds lay brown eggs. The Rhode Island Red, Plymouth Rock, and Wyandotte are the most common brown egg layers, especially in commercial productions.
Egg Color Is Not Linked to Quality
While there are many colorful chicken breeds that lay beautiful brown, blue, or even green eggs, the interior egg quality is not linked to shell color. Brown eggs are not healthier, more nutritious, or superior to white eggs in any way. That’s just an external characteristic.
A brown egg does not have higher levels of protein, vitamins, or any nutritional benefit. The nutrients within brown and white eggs are the same. In blind taste tests, people cannot tell the difference between scrambled brown and white eggs. They taste identical. So while egg shell color provides nice visual variety, it does not indicate the quality or contents inside. Don’t pay more for brown eggs thinking they are better than white ones. The important thing is the diet and welfare of the hen herself, not the pigments in her shell.
Egg Color Is Determined Early
A chicken’s egg color is actually determined long before the egg develops and starts its journey down the oviduct. As mentioned earlier, the egg color depends on the breed and genetic makeup of the hen. So the pigments that color an egg brown or white start developing when the female chick is just an embryo inside the egg!
The gene responsible for egg color expresses itself in the chick extremely early on. So a hen is born carrying her genetic coding for producing brown or white eggs. This genetic basis sets her up for depositing pigments (or not) before the chicken starts laying eggs as an adult bird.
A hen’s oviduct produces the pigments as the egg forms. Then colors like brown get laid down in the outermost layer, the cuticle. So eggs acquire their color quite late as the nearly complete shell forms in the uterus. But again, that color was predetermined long before by the hen’s genetics. An Easter Egger chicken with a white earlobe genetically coded to lay blue eggs can’t randomly start laying brown eggs one day. Her egg color was set at conception.
Temperature Affects Shade
While genetics determine the broad color of chicken eggs, temperature can impact the precise shade and intensity. Hotter temperatures tend to produce darker brown eggs. Cooler temperatures lead to lighter brown eggs from the same hen. For example, a Rhode Island Red may lay a deep mahogany brown egg in summer but a lighter tan egg in winter.
The heat stresses her body and affects the pigment production. Her nutrition can also influence color. A well-fed, heat-stressed hen tends to lay darker brown eggs than a hen experiencing nutritional stress. Free range chickens that walk around also tend to produce darker eggs than confined birds. But the basic color remains fixed based on breed. Just the precise intensity and shade can fluctuate with environmental factors like heat.
Egg Color Diversity in America
For most of America’s history, chicken eggs were diverse shades of brown, white, blue, and green. When birds ran around homesteads, their eggs came in an array of natural colors. Then in the 1920s and 30s, large-scale chicken farming started. The industry chose just a few breeds for mass production, notably the white-egg laying Leghorn.
Egg companies found the uniform white eggs easier to market than a mix of colors. So for decades, most grocery store eggs in the U.S. were white. But since the 1970s backyard chicken keeping has surged. And a renewed interest in colorful heirloom breeds emerged, bringing back brown eggs. Today it’s just about a 50/50 mix of both. So after a period dominated by white eggs, the natural diversity is returning.
Conclusion
Chicken egg color ultimately comes down to the individual hen’s genetics. Hens inherit genes for either white earlobes (leading to white eggs) or red earlobes (leading to brown eggs). Whichever version a hen gets sets her egg color for life. The specific breed of chicken determines which color gene gets passed on.
As an egg forms in the oviduct, pigments called porphyrins get embedded into the outer cuticle to make brown shells. Heated stress increases the intensity of brown. But egg color is decided long before the egg develops based on the hen’s genetic coding. And this color diversity doesn’t affect egg quality or nutrition at all. So while fun to collect eggs of different colors, they provide the same great interior contents regardless of the shell pigments!
