Flint-Hill
Egg Color: It's in the blood.
Globins are members of a structurally and ancestrally related protein family. The most famous face in the family is hemoglobin, the principal oxygen-exchange protein in the bloodstream.
Hemoglobin incorporates a central, iron-containing structure called "heme" which is synthesized and degraded by a tortuously complex series of reactions. One of heme's precursors is protoporphyrin-IX, and that's the principal pigment found in brown eggshells.
One of heme's breakdown products is biliverdin, and that's the main pigment that gives blue-green eggs -- and intermediate-stage bruises -- their color. It's the color called "robin's-egg blue" in the case of the American robin.
Eggshells that contain both protoporphyrin-IX and biliverdin are one shade or another of olive drab. You obtain those by crossing a dark-brown egg layer such as a Marans with a green egg layer such as an Araucana. Depending on the two breeds chosen, hen-to-hen variation, and the number of generations over which the cross is maintained, you (or rather your hen) can produce eggs ranging from off-khaki to dark olive drab.
If you look at the scratches on the eggs above, you'll notice that the brown layer is for the most part deposited on top of the blue-green pigment.
The complete story is a bit more complex, and it can be dragged out almost interminably, but that's the main drift in egg coloring.
Egg Color: It's in the blood.
Globins are members of a structurally and ancestrally related protein family. The most famous face in the family is hemoglobin, the principal oxygen-exchange protein in the bloodstream.
Hemoglobin incorporates a central, iron-containing structure called "heme" which is synthesized and degraded by a tortuously complex series of reactions. One of heme's precursors is protoporphyrin-IX, and that's the principal pigment found in brown eggshells.
One of heme's breakdown products is biliverdin, and that's the main pigment that gives blue-green eggs -- and intermediate-stage bruises -- their color. It's the color called "robin's-egg blue" in the case of the American robin.
Eggshells that contain both protoporphyrin-IX and biliverdin are one shade or another of olive drab. You obtain those by crossing a dark-brown egg layer such as a Marans with a green egg layer such as an Araucana. Depending on the two breeds chosen, hen-to-hen variation, and the number of generations over which the cross is maintained, you (or rather your hen) can produce eggs ranging from off-khaki to dark olive drab.
If you look at the scratches on the eggs above, you'll notice that the brown layer is for the most part deposited on top of the blue-green pigment.
The complete story is a bit more complex, and it can be dragged out almost interminably, but that's the main drift in egg coloring.