Genetic questions!

[Sir Sacabambaspis]

It should be genetically possible.

But actually getting those genes into one chicken may take some doing.

I've seen khaki silver duckwing for sale from Ideal Poultry (Old English Game Bantams, they list it as "Fawn Silver Duckwing.")
https://www.idealpoultry.com/items/fawn-silver-duckwing-old-english-bantam/clean-leg-bantams

So you would need to add the mottling gene from somewhere. Maybe use any bird that is black with white mottling, cross them to the Fawn Silver Duckwing, and interbreed the offspring. You should get about 1 in 16 chicks that show both the Duckwing pattern and the mottling, and depending on how many you hatch, you should be able to find a few that also have the gene for fawn/khaki/dun. Using a black-based bird will let you recognize the wrong e-locus gene and get rid of it (E, Extended Black.) If you try to use something like Mille Fleur (probably E^Wh), it will be harder to recognize which chicks have the right gene (e+/e+) and which are mixed (e+/E^Wh)

Or if you can get "Spangled Old English Game Bantams," cross a Fawn Silver Duckwing rooster to a Spangled hen, then interbreed the chicks. That will be easier than using a black-based bird, because Spangled in that breed is Black Breasted Red (i.e. Duckwing pattern) with mottling. Beware that "Spangled" in some other breeds is caused by a very different set of genes. Spangled Hamburgs and Brabanters and Spitzhaubens will not work for this.
It looks like Cackle Hatchery has some Spangled Old English Game Bantams:
https://www.cacklehatchery.com/product/spangled-old-english-game-bantam/

Meanwhile, you could be crossing one of the Fawn (or Khaki) Silver Duckwings to a bird with barring (such as the Cream Legbar), then interbreed those chicks to get some that have the Fawn Silver Duckwing with white barring.

If you have one bird that is Khaki Silver Duckwing with mottling, and another that is Khaki Silver Duckwing with white barring, you can cross them and then breed a barred chick back to the mottled parent to produce some chicks that have both barring and mottling.

You could end up with bantams for this project. Or, if you use Cream Legbars or any larger birds to bring in the barring gene, you could probably select chicks for size as well as color, and end up with large fowl having this color pattern.

Edit: oops, I was naming USA sources for certain chickens. Since you are in Italy, you will definitely not be ordering from those hatcheries. In that case, I do not know what sources you might have, and what breeds you can most easily find that have the right genes for this project.

If you can't start with a Khaki Silver Duckwing, start with one bird that has Khaki (any color pattern) and one that is Silver Duckwing. Cross them, then breed a chick back to the Silver Duckwing. Pick out chicks that are Dun Silver Duckwing (one gene for dun/khaki), then interbreed those to get some Khaki Silver Duckwings. Or just work with the duns, and them to give the gene to 50% of their chicks, so you have to select for that too in each generation.

Wow this is super helpful and informative, thanks!!! I usually get my hatching eggs from Germany and I don't know any hatcheries in the EU, but I have seen Old English in several color varieties in Germany so I could probably get some from there!

 

[NatJ]

Wow this is super helpful and informative, thanks!!! I usually get my hatching eggs from Germany and I don't know any hatcheries in the EU, but I have seen Old English in several color varieties in Germany so I could probably get some from there!

It seems that the widest color varieties come in some of the small breeds. So Old English can be good.
Also consider d'Uccle or d'Anvers, since many of their colors include mottling, which is one of the genes you'll need.
And any other breed that is bred and maybe shown in lots of colors.

Nothing wrong with mixing breeds for a project like this, just that some of the rarer genes seem more likely to be available in some breed that has lots of colors.

If you have a choice of breeds with a given color, then of course you should also consider what other traits you want (size, body shape, egg color, feathered feet vs. clean legs, crest or muff/beard rather than not, etc.)

 

[Sir Sacabambaspis]

So I've been wondering... Can a hen have two blue egg genes and also have speckling? Like a Legbar egg but with speckles? I've been looking for any examples of this but I haven't been able to find any info on it. I have a hen who lays eggs that are cream in color with dark speckles (photo shows one of her eggs I collected)

If I cross her to my purebred Legbar rooster would at least a few of the daughters lay speckled green eggs? If so would it be possible to back cross them to their father to get a couple hens with two blue genes and the speckling? Would the speckles be drown or dark blue? I find this super interesting and and help with this would be very much appreciated! I've never seen a speckled blue eggs and I can't seem to find much information on how speckling works

 

[Sir Sacabambaspis]

It seems that the widest color varieties come in some of the small breeds. So Old English can be good.
Also consider d'Uccle or d'Anvers, since many of their colors include mottling, which is one of the genes you'll need.
And any other breed that is bred and maybe shown in lots of colors.

Nothing wrong with mixing breeds for a project like this, just that some of the rarer genes seem more likely to be available in some breed that has lots of colors.

I've always been so fascinated by mixing different breeds, but I've realized that sometimes you can end up with mixes that have so many variations it's surprisingly hard to get a color variety you want lol! I've realized that sone color varieties of breeds like silver Columbian Leghorns are becoming increasingly rarer and I hope to cross breeds like Lakenvelders and Silver Duckwing Leghorns and attempting to recreate something with all the Leghorn traits but with silver Columbian, but my calculations end up with like 60 different possibilities... But on the bright side I have more excuses to do big hatches!

If you have a choice of breeds with a given color, then of course you should also consider what other traits you want (size, body shape, egg color, feathered feet vs. clean legs, crest or muff/beard rather than not, etc.)

I have a Thürigian German bantam but I'm thinking he's a form of Chamois spangled, any ideas? Maybe mottling? I'm Germany his color is referred to as Chamois but I had always thought Chamois was just silver laced red?