Egg Information
We see a lot of incorrect information about Celadon quail, the Celadon gene, and what this gene actually does to coturnix quail and their eggs.
"Celadon" is the name for coturnix quail who are homozygous for the "ce" egg gene, which affects egg color. They are not a separate breed, they are not a separate species, and they breed just fine with other corturnix quails, because they are coturnix quail. They just have a mutation that affects their eggs.
So how does the ce gene affect egg color? First let's take a look at what components go into the color we see on normal quail eggs. Here is a normally colored coturnix quail egg.
"Celadon" is the name for coturnix quail who are homozygous for the "ce" egg gene, which affects egg color. They are not a separate breed, they are not a separate species, and they breed just fine with other corturnix quails, because they are coturnix quail. They just have a mutation that affects their eggs.
So how does the ce gene affect egg color? First let's take a look at what components go into the color we see on normal quail eggs. Here is a normally colored coturnix quail egg.
There are four components to egg color- shell color (1), base coat (2), speckling (3), and bloom (4).
Shell color is the color of the actual shell. The shell is largely comprised of calcium carbonate, which is a white compound CaCO3. It is the same compound found in seashells, limestone, and chalk. In quail, it also contains varying amounts of a pigment called biliverdin IXα (and biliverdin iron chelate), which is a green pigment also found in bruises and excreted in bile, that appears blue/blue-green/green to our eyes. This means that the actual shell itself can range from white to blue to green. The egg shells pictured below are all from normal, brown-egg layers with no celadon genes, to demonstrate the range of normal coloration in the shells.
Base coat is the color of the pigment layer that coats on top of the shell and is comprised of protoporphyrin IX, a red pigment that appears brown to our eyes, and trace amounts of biliverdin/iron chelate. This layer is applied in the bird's shell gland, after the shell has been formed, and covers the entire shell. When applied over a white shell, it looks brown, but when applied over a blue or green shell, it sometimes can look green/olive colored. It also varies in thickness of application, meaning the overall egg can look darker brown or very light brown. Here is a photo of an egg whose base coat has been partially removed with vinegar, to demonstrate how it's just layered over the actual shell.
When the base coat contains high amounts of biliverdin, the shell can look green even over a white shell, like the egg below- when opened, this shell was white inside.
Speckling is the color of the dark splotches over the top of the base coat. These are also comprised of protoporphyrin IX and traces of biliverdin/iron chelate, but applied very thickly in some spots. The number and size and position of spots varies from egg to egg, but the variance for a given hen will be relatively small. For example, a hen that lays an egg like the above will likely lay similar eggs over the rest of her life, she is unlikely to suddenly start laying eggs with big dark splotches. Here's an up close of some splotches that smeared, where you can see the red of the pigment (it is not blood, it does not wash off)!
Bloom, also sometimes called the cuticle, is not really a pigment, but a protective outer coating comprised of glycoproteins, lipids, polysaccharides, and inorganic phosphorous. While the bloom is generally considered "invisible," it can appear as a pale frosty color over the egg, and can even change the color of the egg significantly if it's thick enough. Some dark-egg chickens lay "purple" eggs, as the thick bloom of pink over brown looks purple to our eyes. In quail eggs, the bloom will make the egg look shiny, not dull, and it can very slightly change the color we perceive, much the same way a rock looks different when dry vs wet. In the photo below, the egg on the left has a thinner bloom than the egg on the right, and so is slightly more dull/rough.
The egg below is paler overall and has some white spots- these are excess calcium spots, not bloom. Calcium on the outside of the shell can affect the color as well, but is not typical or always present. You can tell the difference by the shininess of the egg- good bloom makes the shell shiny like it's been lightly-oiled, calcium makes the shell rough and white, like below. Here is an egg with excess calcium on the surface. I've wiped a wet finger down the center to show the difference in shell color under the calcium layer.
So, with all of that in mind, what does the celadon gene do?
Well, it doesn't change the shell color to blue. As discussed above, the shell naturally ranges from white to blue to green, without any mutations. But it does reduce or eliminate the protoporphyrin application on the outside of the shell. The base coat is eliminated (usually entirely), and the speckling changes from smooth splotching to raised bumps of calcium and pigment. The gene also, to a MUCH lesser degree, reduces the biliverdin content (most likely that of the biliverdin in the base coat and speckles, but it's hard to say for certain if the biliverdin the shell is affected or unaffected since the studies looking at this did not differentiate).
Here is a photo of a normal egg with a blue shell, beside a normal egg with a pale/white shell. The egg on the right is NOT a celadon egg- it is a normal egg with a blue shell and a very, very thin (or possibly even absent) base coat. This kind of egg fools a LOT of people who don't know better, but retaining it as a celadon egg and mixing the hen that laid it with homozygous celadons can wreck a homozygous line.
Here is a photo of a normal egg with a blue shell, beside a normal egg with a pale/white shell. The egg on the right is NOT a celadon egg- it is a normal egg with a blue shell and a very, very thin (or possibly even absent) base coat. This kind of egg fools a LOT of people who don't know better, but retaining it as a celadon egg and mixing the hen that laid it with homozygous celadons can wreck a homozygous line.
What goes into a good celadon?
While there is no standard of perfection (SOP) for celadon eggs, it's generally considered a good celadon egg if it is large, well-shaped, shiny, and blue, with no base coat, splotching, or other discoloration. Speckling vs no speckling is a matter of personal preference, and each have their own challenges. With speckled celadon eggs, breeders have to be more careful to avoid other discolorations like base coat leakage. With non-speckled celadon eggs, breeders have to be more careful to avoid even minor or pale speckling.
Since egg shell color is not on-off like it is for chickens (there is no "blue" egg gene, just the ce gene that removes brown), and eggs naturally can be non-blue, breeders must be careful to select for bluer eggs (more biliverdin) over time without also selecting for more protoporphyrin expression. This can be difficult, as the same gene is causing the reduction in both pigments, and increasing one may cause the other to increase.
Here is an example of two celadon eggs, but the one on the right is clearly more blue than the one on the left. All else being equal (the eggs are similarly sized, shaped, and with similar amounts of speckling), the bluer egg should be chosen for breeding.
Since egg shell color is not on-off like it is for chickens (there is no "blue" egg gene, just the ce gene that removes brown), and eggs naturally can be non-blue, breeders must be careful to select for bluer eggs (more biliverdin) over time without also selecting for more protoporphyrin expression. This can be difficult, as the same gene is causing the reduction in both pigments, and increasing one may cause the other to increase.
Here is an example of two celadon eggs, but the one on the right is clearly more blue than the one on the left. All else being equal (the eggs are similarly sized, shaped, and with similar amounts of speckling), the bluer egg should be chosen for breeding.
However, not all decisions are as easy as the eggs above, as sometimes telling the better egg can be difficult. Below, the egg on the right is the same egg as the egg on the right above. Despite the speckling lending the left egg some darkness, the egg on the right is still the darker of the two. You can also see that lighting can affect how eggs look in photographs! The above photo was taken directly under my yellow kitchen light, while the photo below was taken in indirect light from the shade of my camera.
Breeding is further complicated by the fact that the males do not lay eggs, and so good breeding may involve several cages with several generations, and seeing which bloodlines produce the offspring that lay the best eggs, not necessarily which individual birds lay the best. A good celadon male can be extremely difficult to find.
The health of the bird should not be disregarded in favor of egg color, either. All of the standards one should expect for wild-egg coturnix (good head and beak shape, straight feet, strong legs, strong wings, well-shaped back, good feathering, etc) are also true for celadons, while also not allowing egg color to slip to white or brown.
Interestingly, no one that I know of has attempted to breed for green (not olive, but clean green as a shade of biliverdin) eggs. It's certainly a possibility, as biliverdin is a green pigment. I've had a few green layers over the last few years, though I have sent them all to pet homes, as I didn't have a wild type line to separate the genes to. Part of the reason I wanted to start working with the wild type birds was to get a mutation-free line that I could outcross to for little side projects like a green egger line. Maybe that will be the next project!
The health of the bird should not be disregarded in favor of egg color, either. All of the standards one should expect for wild-egg coturnix (good head and beak shape, straight feet, strong legs, strong wings, well-shaped back, good feathering, etc) are also true for celadons, while also not allowing egg color to slip to white or brown.
Interestingly, no one that I know of has attempted to breed for green (not olive, but clean green as a shade of biliverdin) eggs. It's certainly a possibility, as biliverdin is a green pigment. I've had a few green layers over the last few years, though I have sent them all to pet homes, as I didn't have a wild type line to separate the genes to. Part of the reason I wanted to start working with the wild type birds was to get a mutation-free line that I could outcross to for little side projects like a green egger line. Maybe that will be the next project!
An Array of Eggs
For this page, I collected an array of eggs in order to showcase some of the differences, and talk a little bit about them, and how they pertain to egg quality in general, and to celadon eggs specifically, as well as to showcase the huge difference lighting can a make in photography of these eggs.
The first photo was taken in cool light- midday light in shade on a bright but overcast day. The second photo was taken in warm light, midday light in full "sun" on the same bright but overcast day. As you can see, lighting in photos plays a huge part in how the eggs look in a photo.
The first photo was taken in cool light- midday light in shade on a bright but overcast day. The second photo was taken in warm light, midday light in full "sun" on the same bright but overcast day. As you can see, lighting in photos plays a huge part in how the eggs look in a photo.
I've numbered the eggs, let's talk about them!
Egg #1 is what an egg looks like without splotching, but with a pale brown base coat. This is NOT a celadon egg; this is an "oops" egg where the hen's shell gland failed to apply the speckling, so all you can see is base coat. Egg #2 is very similar, where the speckling has been interrupted after the base coat was applied. The splotches got smeared!
Egg #3 is an egg with a thin base coat, vs Egg #4 which has a heavy base coat, with about the same amount and type of speckling.
Egg #5 is an egg with normal base coat and light speckling, compared to Egg #6 which is an egg with a normal base coat and average speckling, compared to Egg #7 which is an egg with heavy speckling. Egg #8 also has heavy speckling, with added calcium spots/coating.
Egg #9 is a normal egg with a greenish base coat. The shell underneath is white, and the egg itself is from a non-celadon line.
Eggs #10 and #14 are eggs with high biliverdin content making them look a little more blue-green, with Egg #10 being non-speckled and egg #14 being speckled. Eggs #11 and #13 are eggs with medium biliverdin content, making them look blue, with Egg #11 being non-speckled and Egg #13 being speckled. Egg #12 is a celadon egg, but with such low biliverdin that it looks white, and is not as good a candidate for hatching/breeding from.
Egg #15 is a celadon egg that has remnant base coating. Like Egg #10 and #14, it has a good amount of biliverdin, but is not suitable for hatching/breeding because of the base coat leakage. Compare it to Egg #14, which has about the same biliverdin content, but no brown base coat over the top of the blue.
Science has looked at the hatchability/hatch rate on eggs with different amounts of speckling, and found that heavily-speckled eggs like Eggs #4, 7, 8, and 9 all have worse hatch rates than medium to lightly-speckled eggs, with eggs like #4 and #9 performing significantly worse. Since egg speckling can be affected to some degree through selection, breeders should be careful about this factor when selecting which eggs to hatch. Obviously with Celadons, the speckling isn't as much of a factor, but in my own lines, I've also found that the speckled eggs tend to hatch better than the ones without.
Egg #3 is an egg with a thin base coat, vs Egg #4 which has a heavy base coat, with about the same amount and type of speckling.
Egg #5 is an egg with normal base coat and light speckling, compared to Egg #6 which is an egg with a normal base coat and average speckling, compared to Egg #7 which is an egg with heavy speckling. Egg #8 also has heavy speckling, with added calcium spots/coating.
Egg #9 is a normal egg with a greenish base coat. The shell underneath is white, and the egg itself is from a non-celadon line.
Eggs #10 and #14 are eggs with high biliverdin content making them look a little more blue-green, with Egg #10 being non-speckled and egg #14 being speckled. Eggs #11 and #13 are eggs with medium biliverdin content, making them look blue, with Egg #11 being non-speckled and Egg #13 being speckled. Egg #12 is a celadon egg, but with such low biliverdin that it looks white, and is not as good a candidate for hatching/breeding from.
Egg #15 is a celadon egg that has remnant base coating. Like Egg #10 and #14, it has a good amount of biliverdin, but is not suitable for hatching/breeding because of the base coat leakage. Compare it to Egg #14, which has about the same biliverdin content, but no brown base coat over the top of the blue.
Science has looked at the hatchability/hatch rate on eggs with different amounts of speckling, and found that heavily-speckled eggs like Eggs #4, 7, 8, and 9 all have worse hatch rates than medium to lightly-speckled eggs, with eggs like #4 and #9 performing significantly worse. Since egg speckling can be affected to some degree through selection, breeders should be careful about this factor when selecting which eggs to hatch. Obviously with Celadons, the speckling isn't as much of a factor, but in my own lines, I've also found that the speckled eggs tend to hatch better than the ones without.
We hope that this helps you understand the celadon gene a little better, and maybe some of the other eggs you may see! If you have questions, you can contact Ked via email!