Correct. I'd rather not use muff here as that's usually used for beard/muffs. Perhaps bowtie vs bib? As in baby bib. I've been trying to think of descriptive terms for the visual difference between single/double het/dom dose.
BTW while the difference is most immediate on the neck, there are other signs even on a newly hatched chick. The homs will have naked areas on the face by the eyes while the hets have fully fuzzy faces. Homs also have larger naked areas on their bodies.. most easily seen when the chicks are still wet.. (dry)fluff and feathers does a very surprising job at covering up the naked body areas.
There is a monkey wrench though... pea comb has the side effect of reducing overall feathering. Not noticeable on most birds. However it can be observed when combined with NN- heterozyous pea on a heterozygous NN will have the naked areas around the face, beak and a smaller bowtie(usually somewhere in between a bowtie and bib) and often rather large parallel naked areas on back(again, dried fluff and feathers hide this well). They can fool one into thinking they are homozygous NN.. Also it is rather easy to hit on total clean necks on pea combed birds. I don't think it's possible to tell with these if they are truly clean necked or merely a side effect of pea comb.
Back to single comb NN.. as far as I know, nobody knows why some are totally clean necked.
My first many years in the NN hobby, I never had or saw a clean neck. Really wanted to see a total clean neck so I devoted a single line of hatchery turkens to the sole purpose of hitting on clean necks. No success after several generations.. the closest was some with a single feather on each side of neck.
Then I did egg trade with someone- the chicks were very obviously from a mixed flock, as there were crests, leg feathers, all sorts of combs etc. To my surprise... there were some totally clean necks- all happened to be pullets though so I did not get to do clean neck x clean neck, this group threw some chicks with clean necks but always in low numbers. None of the crosses of these to other "never had clean neck" lines produced any clean necks. Only in later generations did some clean necks show up, also in low numbers.. typical results were something like 2 fuzzies, 5 bibbed, 5 bowtie, 1 total clean neck... or 9 bibbed, 7 bowtie, 1 clean neck.
btw the lines that never threw clean necks started to produce some clean necks after being crossed with this group. Still have not done clean neck bred to clean neck, it's not of strong interest to me plus by chance it just never happened for a cock/hen with this trait to present at the same time in a project I was actively pursuing.
It seems to point towards something recessive and separate from NN gene and needing to be on a homozygous NN to show itself.
This is very helpful, and totally fascinating... I love the puzzle of it!
- Ant Farm