I never expected it, but yet it happened. My rooster laid an egg. This was not a typical brown or white egg. It was a blue colored treasure one might find in a holiday basket.
There are two Ameraucana chickens on our farm. They are one of the few breeds that produce blue eggs (commonly known as Blue or Easter Eggers). It was a tell-tale sign that Bob or Joe wasn’t a rooster when we found the egg. Having one blue egg amongst a dozen brown ones is not fair. I wanted more and needed to know how I could possibly increase this color production.
There are four primary colors of chicken eggs; white, brown, blue and green. Within this spectrum, there are varying degrees of hues ranging from coral, pinkish, beige to deep chocolate brown and beyond.
On average it takes about 26 hours for a hen to create an egg. All chicken eggs begin with white shells. During this day-long process and while the egg is still within the hen’s oviduct, dyes are released. Egg colors are determined by genetics and the breed of the bird.
Brown egg layers apply a brown pigment (protoporphyrin) on the eggshell during the last 5 to 6 hours before they lay the egg. This dye does not penetrate the shell. When you crack a brown egg, the interior of the shell is still the original color of white.
A few hundred years ago a retrovirus was introduced from breeding. This resulted in a gene called oocyan (O). Only a few exotic chicken breeds have the big “O” gene that changes the chemistry of the eggshell and allows the blue dye to penetrate the shell. The blue pigment (biliverdin) is released onto the shell early in the cycle while it’s still in the uterus. If you crack a blue egg, you’ll find that the interior and exterior are true blue both inside and out.
What about the green eggs? They derive from cross-breeding blue and brown egg-producing chickens. The brown pigment covers the blue. Like an artist, this color combining results in a variety of green-hued eggs from light pastel green to dark olive depending on the intensity of the brown dye. If you’re lucky to find a green egg, crack it open and you’ll find a blue interior and green exterior.
It doesn’t matter what color of eggs you have. They all taste the same. My next project is to determine which rooster is laying the blue eggs.