Have you ever noticed that chicken eggs come in more than just white or brown?
Some are blue, green, cream, pink, and even speckled.
It turns out there’s a fascinating science behind these colorful eggs.
The biggest reason for different egg colors is genetics. You can often tell what color eggs a hen will lay just by looking at her earlobes.
Hens with white earlobes usually lay white eggs, while those with darker earlobes often lay brown or colored eggs.
But actually, all eggs start out white because their shells are made of calcium carbonate. The color comes later, thanks to pigments added during the egg’s formation inside the hen.
As the egg moves through the hen’s body, it goes through a five-stage process. During the fourth stage, pigments are deposited onto the shell, giving it its final color. Different breeds produce different pigments.
For example, White Leghorns lay white eggs, while Rhode Island Reds and Plymouth Rocks lay brown ones. The brown color comes from a pigment called protoporphyrin, which is added late in the process, so the inside of the shell stays white.
Some chickens, like the Ameraucana, lay blue eggs because they deposit a pigment called oocyanin, which colors the shell all the way through, inside and out.
Cross a blue egg-layer with a brown egg-layer, and you get olive-colored eggs. Other colorful egg layers include Araucanas, Dongxiang, and Lushi breeds.
Speckled eggs are also natural and happen when extra calcium is added during shell formation. It can be caused by small disruptions in the process or even by excess calcium in the hen’s body. Although speckled eggs might look unusual, they can actually be stronger than regular eggs.
While genetics decide the egg’s basic color, other factors can change its appearance a little. Age, diet, stress, and environment can make eggs slightly lighter or darker. For instance, older hens might lay bigger but paler eggs.
Stress from disease, heat, or overcrowding can also affect the egg’s size and shape, sometimes leading to oddly shaped eggs.
If you’re wondering about yolk color, that depends on what the hen eats, not the shell color. Hens that eat plants rich in yellow-orange pigments tend to lay eggs with darker yolks. Hens fed mostly corn or grains lay eggs with lighter yolks.
Research shows that while darker yolks and lighter yolks have similar nutrition, pasture-raised hens’ eggs often have more omega-3s, vitamins, and lower cholesterol.
And here’s a fun fact: sometimes a hen lays a double-yolk egg. It happens when two yolks are released too close together, usually in young hens whose bodies are still getting the hang of egg-laying.
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