Help with egg color genetics please

[dheltzel]

Yes- 1 gene there are 4 possibilities. 2 genes there are 16 possibilities. 3 genes 64 possibilities. It grows at an exponential rate. What I don't know, and can't seem to find anything definitive on, is just exactly how many genes are involved in making brown eggs. Everyone says it's "a lot" but there has to be a fact somewhere that that opinion is based on. I just can't seem to find it. Until I see something definitive I'm going to assume two factors.

I believe that no one knows how many genes are potentially involved, and some inhibit rather than produce brown, so if a hen lays a white egg, it could be missing the brown genes, or have the inhibitor genes.

And if you finally decide there are X, what if someone discovers a new one ? I don't know the number, but 2 seems far too easy to map and explain, so that is very unlikely to be the number. I would suggest at least 4, probably 10 or more.

 

[tbishop]

 

[Sonoran Silkies]

I looked through this section and got a lot of info but none specifically for my question-

If you bred a blue egg layer (LLrr) to a brown egg layer (llRR), you would get green egg layers (LlRr) that carry recessive white shell and recessive no tint genetics. Is that correct?
......

I hear that it takes many generations to get back to blue eggs. This isn't suggested by the punnett square above. Is it because of how few out of the whole flock would be female with the right genetics or is it because the brown egg component have multiple factors?

Not sure what your L and R are? Eggshells are either blue or white. The gene symbols are O and o+, respectively. Brown eggs are the result of a layer of brown pigment overlaying a white eggshell. Green eggs are the result of the same brown pigments overlaying a blue eggshell. OO shells are a darker blue than are Oo+ shells. There are at least 13 different genes that cause or prevent (mostly cause) brown pigment.

Brown egg shell color is controlled by multiple genes and that they all act independently for the most part. That is why there are so many shades of brown eggs. There is a gene that suppresses all brown egg colors at once, that is present in most commercial leghorns. I've heard it also can partially suppress blue, but I'm not certain of that, and hope it doesn't.

Basically, you need to change the Punett square from 4x4 to about 10x10 or something, so getting all the brown out (or back) is a real challenge.

No, it doesn't suppress blue; that is entirely different. 14x14 is more like it. Even thinking of the number of variations makes my head hurt!

If you do the math, you'll realize that once you are trying to control more than 2 or 3 genes you need to hatch hundreds or thousands of chicks to be guaranteed of getting your desired results. Since the inter-relationships between these genes (and the genes themselves) are not well understood (compared to genes like blue egg color and chick down color), you are really just selective breeding for whiter (or bluer) colors to get the brown reduced. Since the males never show a phenotype for egg color, but definitely contribute to the genotype, it makes this even harder.

Eggsactly. Best bet is to use males that already come from a line of birds that reliably lay the colour you want.

I have proved (at least to myself) that the white leghorn egg color genes can suppress the blue color gene somewhat.

I bred my black Araucana rooster to white leghorn hens and got pullets that laid pale blue eggs. I was disappointed and posted on here about it. Someone on here mentioned the color suppression facts.

So the next spring I changed to brown leghorn hens. The resulting pullets laid a much much bluer egg.

So was that the 'suppressing' genes at work?

Blue pigment, just like brown fades over the course of a laying cycle; OO birds lay a darker blue egg than Oo+ birds.

Yes- 1 gene there are 4 possibilities. 2 genes there are 16 possibilities. 3 genes 64 possibilities. It grows at an exponential rate. What I don't know, and can't seem to find anything definitive on, is just exactly how many genes are involved in making brown eggs. Everyone says it's "a lot" but there has to be a fact somewhere that that opinion is based on. I just can't seem to find it. Until I see something definitive I'm going to assume two factors.

At least 13 documented genes for brown eggs.

 

[tbishop]

Not sure what your L and R are? Eggshells are either blue or white. The gene symbols are O and o+, respectively. Brown eggs are the result of a layer of brown pigment overlaying a white eggshell. Green eggs are the result of the same brown pigments overlaying a blue eggshell. OO shells are a darker blue than are Oo+ shells. There are at least 13 different genes that cause or prevent (mostly cause) brown pigment. L would be blue; l would be white. R would be brown; r would be white.


Blue pigment, just like brown fades over the course of a laying cycle; OO birds lay a darker blue egg than Oo+ birds. That's what I was trying to express with the LL and Ll. I just took the second letter of the word because they both started with "B".


At least 13 documented genes for brown eggs. Can you cite a source for that? The original study(s) would be great! I've seen mention of anywhere from 8-13 alleles in forum discussions across the internet. I've found that in the course of the internet "telephone" game the original facts often degrade in accuracy.

Thanks for responding! Any kind of input helps me get closer to understanding the truth.

 

[dheltzel]

You won't be able to get a definitive number, just one you can work with. Maybe there are 8 common ones, 5 more that only some people have experience with, and who knows how many more that have not been found yet. Just because you find a paper where a scientist says there are X alleles, doesn't make it so, that's just his/her opinion with the research they have done. There could be 40 alleles, or 100, there could even be new mutations that are just occurring now.

You quest to find "the number" is a fools errand, IMO. You like 8? Go with that. Practically, it makes little difference to your breeding program whether there are 8,13, or 200. You will, in the end, be doing selections for egg color based on the phenotype of the hens and hoping their male progeny carry what you like about their phenotype to the next generation.

Getting a very white egg is hard, getting a very dark egg is maybe even harder. The incredible range of colors in the brown range makes this an exciting opportunity in empirical experimentation, but make Punnet square type phenotype predictions a futile exercise.

Did you know there is also a gene that gives the shell transparency and a glossy shine. That may not directly affect the color, but certainly our perception of the color.

 

[tbishop]

I'm often the fool .

It sounds like this is essentially folklore and everyone chooses what they are comfortable with without any actual documented fact to back it up. If that changes, I hope to read something definitive to help me understand the process. Thanks for the input!

 

[Sonoran Silkies]

Quote:
Go to Classroom-at-the-Coop and search on blue eggs. select posts by Ron O or Rokimoto (same person--Ron Okimoto, probably the best poultry geneticist of our time).

 

[tbishop]

Go to Classroom-at-the-Coop and search on blue eggs. select posts by Ron O or Rokimoto (same person--Ron Okimoto, probably the best poultry geneticist of our time).

AWESOME!!! Thank you!

 

[hwd2002]

Oh sorry

 

[Jayzandra]

I know this is an old post, but I would like to share my newbie experience.

I hatched out a couple of batches of eggs out this last spring. I only had one rooster at the time. A Wheaton Ameraucana. The hens were a Wheaton Ameruacana (she lays very large, very blue eggs) and an Cuckoo Marans (she lays medium dark brown eggs). So, I only got one pullet from each hen on the first hatch. The Ameraucana daughter now lays large mint green eggs. The Marans daughter lays brown eggs. I was disappointed because I was hoping for Olive Eggers. So, I was thinking the rooster probably isn't really an Ameraucana after all. The second batch of chicks I got 3 pullets from the same Marans. All three of them lay really olive eggs. So I was just a little perplexed until I read this post because they all have the same dad.

So what I'm basically getting from this is dad (or any chicken for that matter) can carry genes for both blue eggs AND brown eggs?