Hi FMP. I am glad you showed up and think you can contribute a lot to the discussion since you have Cream Legbars, are experienced at showing and have birds that are most probably split for Cream.
I think that back in the day, the folks that had Brown Leghorns really didn't appreciate that there was an e+ and an eb genetics going on and they were both combined into one breed**. After a time they came to realize that e+ produces a salmon colored breast in females and eb produces a breast the same color as the back in the females--the boys pretty much look the same. Brown Leghorns were accepted into the APA SOP in 1874 and split into Light Brown and Dark Brown in1923. The APA was formed in 1873 so the Leghorns were in the first Standard they published. I don't have that reference so I don't know how the original Brown variety description varied before and after the split. FMP--Do you have that reference by any chance?
The way I see it is the Cream Legbar as it was admitted in Britain, was a variety based on the Genetic Variant ig that was discovered. The genotype is ig/ig, the phenotype is Cream. The Silver Legbar was based on the genotype S/S (S/-) and the Gold was based on Ig/Ig. For me I think it is pretty straightforward that Cream is referring to the genetic state of the bird. Punnett in one of his papers (
http://www.ias.ac.in/jarch/jgenet/48/327.pdf and the paragraph about the secondaries is found just above the entry "Rhode Island Red Cross" on page 329) describes how red doesn't show up in the wing triangle, only gold. So looking to see if there is gold in that location is the best way for a breeder to get an idea if their bird is ig/ig or Ig/?. It is a tool in the tool box to decide what you have. The breed standard (original British) allows for chestnut in 4 places--the back. shoulders, coverts (qualified as some chestnut smudges permissible) and crest. I think they left it off the secondaries because there is no red there and because the gold gets diluted by cream in that location. Otherwise the standard would read as it did for the gold variety: "primaries and secondaries dark grey barred, intermixed with white, upper web of secondaries also intermixed with chestnut"*
So for me, I am using that gold or lack of gold in the secondaries as my litmus test help me understand the underlying genetics I am dealing with in my flock. Having gold in the wing triangle alerts me that there may be an issue with dilution genetics piece to the puzzle, but for me it doesn't mean I need to cull that bird or that they are not a Cream Legbar. The problem as I see it though, is that if I ignore the gold there and turn down the chestnut, turn down the barring, turn down the melanizers in my bird to achieve a phenotype that matches the standard (except for the gold in the wing triangle) then I am setting myself up for problems down the road with getting too light of a bird when I hatch the ig/ig version of the Ig/ig father. I think to a certain extent this is how we end up getting lighter and lighter birds.
SO the big question I have for you FMP, and also for anyone else who cares to answer--and this is the crux of the conflict between folks about color in the Cream Legbar--
Does the Cream Legbar mean to you:
a) The Cream is a genetic designation for this variety of Legbar and the ideal bird should be ig/ig
b) The Cream is color of bird and can be diluted with 2 copies of ig/ig or can be Ig/? and the ideal bird just needs to match the standard
How does the APA view the variety Cream? Is it a color or a genetic state? Can I show a bird that is white under a traditionally silver if they look the same or would that be viewed as wrong? A BYCer once suggested that he could recreate the Cream Legbar by introducing silver as a substitute for Cream. I was not happy by this suggestion, but if look at Cream as a phenotype and the following reference seems to indicate that Cream and Silver look the same in the males (also referenced in the Punnett Cream Paper) then why would that be wrong as long as the bird looks cream in appearance?
In Sex-Linkage in Poultry Breeding Bulletin No.38 - Punnett & Pease say- 'An interesting new autosexing variety is the Cream Legbar.
The cream colour is undistinguishable to the eye from the silver : but cream is none the less a form of gold. It may be thought of as an extremely diluted gold .The Cream Legbar has a crest, which distinguishes it readily from the Silver Legbar.Its most striking peculiarity is that it lays blue eggs. The sex-distinction in the downs is the same as that in the Gold Legbar'***
(from:
http://www.the-coop.org/forums/ubbthreads.php?ubb=showflat&Number=109450 )
I realize the judges don't have a genetic test kit (or wouldn't if there was one available) so what do they think about this issue? Should the birds be ig/ig or just look Cream? It all comes down to Phenotype vs Genotype.
* The gold Legbar standard was admitted into the PCGB in 1945 a more detailed history is
http://blue-eggs.co.uk/#/history-of-cream-legbars/4554275782 Obviously, the chestnut referred to in the Gold Standard is genetic gold, not red.
**For those of you reading the post that are not up on genetics, e+ is wild type and often referred to as duckwing (the wing triangle matches the hackles and saddle) where eb is often referred to as partridge (although to confuse matters, partridge in Europe means duckwing--they are not the same!)
***the British downs description now reads Cream, as for Silver. When I look at the two down descriptions they are almost identical with very few minor changes--I am not sure of the date on the above reference--it may have come out about the time the Silver Legbar was accepted and thus not well known.
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