To increase the diversity of egg colors that our hens produce, we cross our Black Copper Marans (chickens that lay dark brown eggs) with Blue Ameraucanas (layers of blue eggs). The result is a hen that lays large, camouflage-colored eggs. (The hens are also very vigorous, as they are “hybrids.”)
The way this works is interesting. Eggs come, basically, in two colors: white and blue. You can see this when you crack them open. A white egg is white, from both the outside and the interior; the blue egg is also the same color from both sides. But, you say, I buy whole-wheat eggs . . . and they are brown! This is so because a brown-egg-laying hen deposits a brown-colored substance overtop a white-colored shell as it passes through her oviduct. Break open a brown egg and you will see this: brown on the outside, white on the inside.
What the Olive Egger hen does is lay a blue-shelled egg (because she carries the dominant blue gene from her Ameraucana parent) and then covers it with brown paint (a trait she acquired from her Marans parent). The result is a green egg.
But sometimes this does not work as planned. Over the past few years, as we have experimented with our Olive-Egger creation, we discovered a genetic irregularity with the line of Ameraucanas we were working with: Some of the hens were heterozygous for the dominant blue-egg gene. We divined this by noting that some of our “Olive Egger” hens laid brown, not green eggs: brown paint over a white shell. Had the hens been homozygous for the blue trait, this would not have happened.
As a consequence, we sold off all of our Ameraucana stock and started over with birds from a different source. We hope that this will work out better, that all of our new hens will be homozygous and that all of their daughters will lay the beautiful green eggs that this ingenious crossing can create.
In 2015 we will be creating Olive Eggers by putting “Bloom,” our new Black Copper Marans rooster, over our four Ameraucana hens (three splash, one blue).