Shell colour, curious...

[IggiMom]

I notice that there are sometimes offers for 'olive eggers' on the forum. Interesting. People are breeding Marans and EE's to get them. I don't see why it would, although I guess the test would be in the eggs of the chicks.

The EE's lay a green egg and the shell is green all the way through.

The Marans and Wellsummers lay dark brown eggs and the dark part is 'painted' on. It seems to me like a completely different mechanism, but I am no expert, just wondering.

I thought that shell color came through the roo, or mostly so, so I have been trying to keep Roos from my really deep blue eggs. (This is what I want, deep blue. I don't really care at all about olive eggs, I am just wondering.)

I actually do GET a few olives from my EE's and they are ok with me, but the ones I am hoping for the deep blues are my Wheaten Ameracaunas.

Catherine

 

[alicefelldown]

Quote:
Actually, it's easier to use a pure blue laying bird instead of an EE mutt to get a nice olive egg. EEs are great, but they can be a mixed bag genetics wise.

Now as to why the colors exist and how they are made?

Well, eggshells are made of the calcium carbonate and can come in either white or blue, but not brown.

As an egg develops within a bird's reproductive system, the shell is laid down as a liquid mineral layer around the already-formed membrane (which formed around the white and yolk). Pigmentation is added to the shell by papillae lining the oviduct, coloring it any of a variety of colors and patterns depending on species.

The blue shell pigment is called Oocyanin which is a byproduct of bile formation and is visible throughout the shell. It can appear in different shades of blue and most commonly tends towards green. The blue gene (O) is dominant over white; when blue and brown genes are present the shell appears to be green. You can see this when you crack an egg and peel off the inner membrane.

Brown shells are the result of a pigment called Ooporphryn, which is a chemical compound resulting from hemoglobin metabolism and it is deposited on the surface of the egg shell. Deposited on a white shell, the egg appears brown, and on a blue shell it appears green. Depending on the breed (after many generations of selective breeding) brown eggs can vary in color from light cream to dark brown.

The olive colored eggs are a result of mixing that dark dark brown with a good blue layer – so a nice blue shell, coated in brown ‘paint’.

 

[IggiMom]

Well, that was interesting. Very.

So are you saying that the shell color does not come through the roo, as I thought, but is inherited equally?

And the painted on brown seems to be true of the dark brown breeds. If you try, and sometimes even if you don't, you can wash it off--but not, for example, from the eggs of BO's or RIR's, who seem to be cream or brown throughout.

I am really interested in this.

I wonder how I can get deeper blue eggs--I would assume simply by breeder for them.

Catherine