|Olive eggs from my Olive Eggers, bred by me--with two white eggs for comparison.|
UPDATE: My Olive Eggers are laying olive eggs! This picture (above) shows what colors they are producing, and read more about where we are now in the Olive Egger project here.
The basic genetics, without boring everyone to death or getting beyond my own understanding, goes like this. A chicken carries egg color on multiple gene locations A bird can carry blue egg genes or brown egg genes, or BOTH. When they carry neither, they lay white eggs. When they carry only a few brown genes, they lay light brown eggs. More brown genes = darker brown eggs. When they carry only blue genes they lay blue eggs. When they carry copies of both, they lay some shade of green egg. To get dark or vibrant olive green, you need one dark dark brown and one bright bright blue gene carrying parent.
Only a few breeds of birds lay a true blue egg--Ameracaunas and Auracanas are the main ones, both of which are fairly unusual and can only be acquired from a breeder, as hatcheries do not carry them, no matter what they say. Easter Eggers are a mixed breed, and the term EE indicates a bird whose ancestry passed down to them at least one copy of a blue egg gene and which has a pea comb and lays, usually, an egg in the blue-green color range. In these birds, which usually lay a minty green or sea green egg, it is fairly unusual to find a blue egg, though focused breeding of the bluest-egg-laying EEs can provide a reliably bluish egg--but even then, they are still EEs. Egg color does not make for a breed, after all--heredity does. Hatcheries refuse to stop labeling their EEs as Auracanas/Americanas, and so many many folks are understandably confused about the difference! Interested? Read more about all that here: EEs vs AAs.
Many many birds have copies of the brown egg gene. French Coppered Black Marans (FCBMs) lay the darkest egg of any breed, as seen in the pic to the left.
What happens when you take the bluest egg you can find, like the one in the middle of this picture, and the darkest brown egg you can find, like those chocolate brown beauties surrounding it, and cross the parents? You may get a deep or vibrant green egg, from mixed breed birds called Olive Eggers. The deep green or true olive is above and to the left of the blue egg; the vibrant jade green egg is below and to the left of the blue egg). Once you get green eggs like this, breeding strategy consists of taking the greenest of these olive eggs and breeding the hens that lay them back to dark brown egg roosters, and French Coppered Black Marans roos are the best.
I am so excited to see what color eggs I will get from this batch of hens, who are bred from very blue-egg laying EEs crossed with FCBMs and from pure FCBM hens crossed with a pure Ameraucana rooster. My best FCBMs lay a huge speckled dark brown egg, which means that my eggs may also be olive and speckled--an amazing, beautiful combination! A few of the birds in this hatch will lay or carry genes for plain brown or khaki eggs too--in cases where their (heterozygous) EE mothers carry only one copy of the blue gene, a few of their offspring will revert back to brown eggs, but this should be a small percentage.
Are you interested in raising chickens that may lay dark brown, blue, blue-green, or olive eggs? I will have chicks available in mid April that should lay eggs that span the spectrum of these tones. Let me know if you'd like to reserve some! They start at $4 each as day old birds, and their price increases $1 each week to $8 at 5 weeks, when they are ready to live outside.