My Edible Garden

I've been gardening for most of my life and have been a devoted fan of organic gardening the whole time. It just makes so much more sense to work in harmony with Mother Nature than to fight her. Besides which it is better for the planet and better for our bodies. Here you can see what I'm planting and harvesting, with gardening hints and resources thrown in for good measure.

Wednesday, September 4, 2013

Egg Shell Color Genetics

Easter Egger pullets
I thought it was about time to give you an update on those cute little chicks up at the top of the page. Those are some of the 30 or so chicks that hatched on my birthday in April so going on 5 months old. They are part Ameraucauna, so actually just mutts, but some will lay blue or green eggs. Ameraucauna chickens lay blue eggs and have a small pea comb. Apparently the pea comb and the blue egg gene are closely linked, so in general if they have a pea comb they are going to lay blue or green and if they have a single comb then they will lay white or brown depending on the mix of breeds they are.
single comb on left, pea comb on right

So how do we get green eggs? Well there are actually only two colors of egg shell, blue and not blue. What I am talking about is the color of the shell itself, all the way through. If you open up a blue egg and look under the inside membrane, you can see that the inside is blue also. But when you look inside a brown egg the inside is white (genetically, "not blue"). You see in a blue egg the blue pigment is an integral part of the egg shell. However, in a brown egg the brown pigment is actually a coating put on the outside.

A green egg happens when a bird has the blue egg genes along with some of the brown egg genes. She makes a blue egg shell and then coats it with the brown coating. The shade of green it turns out to be depends on the brown genes and the amount of brown tint she adds.
As you can see there are a variety of colors and patterns on these girls. Some have single combs (and so will probably just lay brown eggs) while others have pea combs (and so will lay blue or green).  Some have great muffs and beards and some have clean faces. Purebred Ameraucaunas are required to have muffs and beards by their breed standard and I do think they are cute. But beards and muffs have nothing to do with the blue egg gene, so as long as they have a pea comb they will probably lay blue/green eggs, even if they have a clean face.

And some of them have begun to lay already!
I can't wait to see what other colors I get out of these girls!


  1. Mary, you have Easter eggs without the mess of food color dying. I didn't know there were so many things to know about egg shells. I have not see eggs that are blue or green. The chickens on farms here in Nebraska are either white or brown. I'm not convinced that the color of the egg shell has something to do with nutrition of the egg. The stores here will advertise the brown eggs are better eggs and price them higher.

    Have a great day with the chickens.

    Nebraska Dave

  2. Hi Dave, good to hear from you! You are right, the color of the eggshell has NOTHING to do with the nutritional content of the egg itself. I think this got started at some point when white leghorns became popular for mass production in cages, where smaller farms were still raising brown layers. Much more important is the diet and conditions the chickens are kept in, in this case it really does help to know your farmer!