Cackling Easter: chickens color the eggs themselves

Chickens lay white and brown eggs, you already knew that. But did you also know that you can tell whether a chicken lays brown or white eggs by its earlobes? Hens with white earlobes lay white eggs, hens with red earlobes thus lay brown eggs of all shades and…..yes…sometimes green, blue or olive-colored eggs too! So while in many households and elementary schools just before Easter, white eggs are dyed and decorated in all kinds of ways, there are breeds of chickens who color their own eggs.

Brown eggs

Most chicken breeds with red earlobes lay light brown eggs, sometimes these are almost white, but e.g. the Barnevelder lays really brown eggs and the Welsummer lays brown eggs with dark brown dots. The French Marans takes the crown with very dark brown eggs. The brown shell color occurs because brown pigment, protoporphyrin, is added to a greater or lesser extent during shell formation in the oviduct.

Blue and green eggs

But what about blue and green eggs? Here, too, a pyrrole (dye) plays a role, namely biliverdin, a bile dye. Chickens that lay blue to green eggs carry the gene Oöcyan. This gene is the cause, that the green bile dye gets into the shells and shell membranes of the eggs. This causes it to act as a pigment, so to speak, which in turn results in many different shades of blue and green eggs. We also call chickens with this gene green-leggers, blue-leggers or Easter-eggers .
Dominant color gene
Chickens with the Oocyan gene in them have passed it on from their parents. In addition, this gene is also dominant. This means that the chicks of these chickens will most likely lay colored eggs, even if they are crossed with chickens that lay white or brown eggs. However, there is a big difference when crossing a hen with the gene O with a hen that lays white eggs or a hen that lays brown eggs. A cross with a hen that lays white eggs will in fact give blue eggs, where a cross with a hen that lays brown eggs will give green eggs.

Green is just as tasty

Apart from the color of the eggshell, there is really no difference between green, blue, white or brown eggs. The inside is the same as “normal” eggs and the taste is the same as well. Only the eggshell may want to be slightly thicker, which reduces the chance of harmful bacteria entering an egg. Unfortunately, the common comment that green eggs contain less cholesterol is a fable.

Several breeds are color layers

Chicken breeds with the Oöcyan gene include the Araucana (a Chilean fowl that often has ear tufts and a bulbous tail), the Ameraucana (Araucana from which the ear tufts have been bred out because they are linked to a lethal gene, which makes some of the chicks unviable)), the Dutch Schijndelaar (bred from the Araucana, the Sumatra grouse, the Brabant farmer’s grouse and the Leghorn) and the Cream legbar (a Plymouth Rock cross with leghorn and Araucana).
A separate group are the olive leggers. This is not a breed but an F1 cross of green-laying hens with a cock of a breed that lays dark brown eggs, such as a Marans or Barnevelder cock. The result is olive or khaki colored eggs.

Happy Easter and tap a colored egg!

Hans Krudde
(Pictured left to right: top: Araucana, Marans, Marans,Orpington, Australorp, bottom: Olive laying, Schijndelaar, Olive laying, hybrid laying hen, Schijndelaar)