Egg color (shades of brown) and the E gene...

[U_Stormcrow]

I'm embarking on a project (started, actually) to try and cull my way into a backyard mutt with some desired traits. My Roo is of unknown genetics, and some of my starter hens are hybrids, so... I know I'm rolling a lot of dice.

All of my eggs currently run shades of cream to brown, and I'm hoping to eventually end up with something consistently closer to cream than brown. In the first two batches of offspring, some of my babies appear to have slate legs, are generally darker overall, and pronounced black markings on the beak.

Query One) Is this indicative of the E gene?

Query Two) While the effect on beak and leg color is obvious, is it ALSO associated with darker tinted eggs? (I'm not looking for blue/green here, just wondering if the gene has any impact at all on the darkness of shell tinting?)

Query Three) Are there other genes, particularly red genes, that have impact on shell tinting (darker/lighter)?

Thanks in advance. I've read a bunch of pages that focus on the primary effect of various genes, but not so much about how they might affect other characteristics of the birds, or combine with other genes to have secondary effects.

 

[NatJ]

I've read a bunch of pages that focus on the primary effect of various genes, but not so much about how they might affect other characteristics of the birds, or combine with other genes to have secondary effects.

Sounds a lot like what I've found.
None of these affect your egg color project, but I'll list the other effects and interactions I can remember reading about.

Genes with other effects:
--homozygous pea comb makes smaller wattles and a bare line on the breast
--beard makes smaller wattles
--homozygous rose comb is associated with reduced fertility in roosters
--homozygous v-comb changes nostril shape
--homozygous short legs is lethal
--homozygous ear tufts is lethal
--recessive white reduces growth rate

Genes combining to give other effects:
--two leg color genes make four colors
--egg color white/blue/brown/green
--pea comb + rose comb = walnut comb
--pattern gene interacts with a few others to affect how pigment is distributed (spangled, laced, double laced, etc)
--dilution & coloring genes can stack up, like blue + chocolate or lacing + barring + blue, but those seem to just be each gene adding or subtracting from the results in an obvious fashion, so I feel that they don't really count.

 

[U_Stormcrow]

I found a "great" source yesterday on egg tinting, and I've seen the charts of course - those are simple, kindergarten level genetics. It was where the site said there were more than a dozen genes affecting egg color that made me stumble in my reading, and then it moved on to the next topic without identifying the genes much beyond O and o...

The comb genetics, after my earlier error, I'm pretty good on - particularly now that I've moved beyond reading to experience, since the online images showing rose combs tend to focus on the prominent male comb, not the comparatively tiny hen comb. and there aren't that many genes involved. Getting good on skin genes, too. Again, not that many combinations.

Pattern genes, honestly, I'm struggling - and there aren't that many more genes involved. Red coloration, too - particularly identifying what will become adult red in pale markings on chicks.

But eggs? I though that would be simple. Seemingly not.

Thanks again @NatJ, I greatly value you as a resource here.

 

[halefamily_flock]

I'm also very interested in understanding shades of brown. Here's what I've been able to piece together, so far. Still very high level and I don't know how to figure out which chickens have which genes, or how these relate to O/O...

Eggshell genes
Protoporphyrin IX

1. CPOX - high expression = brown shell
2. FECH - high expression = lighter color shell
3. BCRP - high expression = brown shell
4. HRG1 - high expression = white shell
5. FLVCR - high expression = lighter color shell
6. SLC01A2 and CLC01C1 - high expression = brown shell

Biliverdin

1. SL01B3 - high expression = blue/green shell

Shell color intensity can be measured by shell reflectivity %, with higher value = lighter egg. Spectrophormetry can be measured by something like this: cm-600d-spectrophotometer

Reference articles attached

 

[halefamily_flock]

I found a "great" source yesterday on egg tinting

Do you mind sharing your source?

 

[U_Stormcrow]

Do you mind sharing your source?

Not at all. It was Scratch Cradle, which really just links (sadly, one I really wanted was broken) to a number of different sources being shared around the web. Scratch has a whole series of simply written guides. Which are helping me with Kippen - though I still lack enough practical experience to make the jump between letters and visualization, but I've more than a trace of Aphantasia, so that's always going to be a struggle.

 

[halefamily_flock]

I struggled with Kippen initially, until I found a few other resources that helped me visualize the feather colors & patterns that related back to the genes in the calculator. The resource that helped me finally make the jump from letters in a chart to visualizing the impact of various genes was this one: 21st-Century-Poultry-Breeding
It is expensive in print, but the kindle version is affordable and it has lots of illustrations.

The other resource that helped me visualize was this youtube series:
Chicken Genetics Series from Chickens in my Garden

After watching the series, I started mapping my breeds in simplified, manual pencil & paper Punnett squares for the genes I actually cared about (similar to what she does in the videos), and then, when I went back to Kippen, I was able to focus just on the genes that mattered to me vs. being overwhelmed by all the detail.

Once I was able to start visualizing things, this book was very helpful. It has good explanations but no illustrations. An-Introduction-to-Color-Forms-of-the-Domestic-Fowl

Of course, none of the above sheds any light on egg color, but once I got the hang of feather colors & patterns, I felt confident enough to tackle some of the less documented genes. Combs were my next interest area, specifically crosses of Duplex and Rose combs, which I did some research and have started conducting my own experiments with. Here is a good thread for info on combs: multiple-comb-type-breeds

The next time I have a research day, I'm going to try to dig further into egg shell color. I have several experiments in the brooder now, and a few more planned for spring. Hoping to learn enough to make a few predictions in advance of POL in April/May.

 

[U_Stormcrow]

I was asking for my Lemonade project. One of my eventual desired outcomes is a cream to tan, rather than tan to brown, colored egg - and if the E gene which is so readily identifiable in chicks - was in any way responsible for darker tinting in eggs, I wanted to quickly get it out of the flock before I start thinking about F2, either by frying, stewing, stuffing as sausage, or selling as chicks. Seemingly, I'm going to have to demonstrate greater patience.

Oh, and I've been unable to locate the PDF previously published by NSPPA - in spite of considerable searching and direct inquiry of them. Their site is down, no longer maintained, and the documents gone.

 

[halefamily_flock]

I was asking for my Lemonade project. One of my eventual desired outcomes is a cream to tan, rather than tan to brown, colored egg - and if the E gene which is so readily identifiable in chicks - was in any way responsible for darker tinting in eggs, I wanted to quickly get it out of the flock before I start thinking about F2.

Sounds like you would like the light cream eggs that just came from my black crested beauties (Sex link Spitzhauben-Dominique crosses) chicken-math-genetics-experiments-in-southeast-missouri

I haven't found any research linking E (Extended black) with egg color, and the black pullets that just laid me really light cream eggs were ER/E, so it doesn't seem to be causing any problems in this very small sample. The basic idea for brown egg shells is that the offspring will split the difference between parents, in terms of darkness. So, in this example, crossing pure white-egg spitzhauben with tan egg Dominique, resulted in a light cream color that split the difference.

Rather than worry about E genes, you may want to introduce a pure white layer (e.g. a Leghorn?) into the mix before you move on. I don't have personal experience, but have considered bringing in a brown leghorn since it wouldn't mess up any of my desired feather patterns or colors and would increase productivity vs. my Spitzhauben and Hamburgs (my current white layers). I ultimately decided against it, thinking I can get very light cream, if not white, through these Dominique crosses (as well as Speckled Sussex, which is my lightest tan layer).

 

[U_Stormcrow]

I wasn't worried, so much as looking for some quick eliminations - but you are the second offering anecdotes that there are no clear/apparent links between E and egg color, so at least I know that breeding those birds (if they have other desired traits) isn't leading me to an unproductive evolutionary end in my program, at least from an egg color perspective.

By summer, I am going to have too many eggs, and too many birds, so I'm already thinking ahead to what traits to cull first. Really don't want to exceed 60 birds +/- at any one time, and if I can't find a market for the excess to cover feed costs, I'll need to scale back.

I do already have some light cream egg birds, such as the Wyandottes which are just starting to lay, so I can back cross to those If I get some of the other traits I want in a roo from one of the current generations - as the SLWs have acceptable, though not preferred, patterning. Just no reds in their plummage which is my other primary goal, followed by weight gain.