Barring, double barring

[Medodge]

I’m really enjoying learning all things chicken. My medical background makes me really curious about specific genetics. Is there anyone out there who has the time to explain (and post pics, I’m a visual learner) of the reasons and examples of double barring vs single barring.
Thank you so much

 

[Amer]

Barring is a sexlinked gene that basically prevents pigment from showing up in stripes along the feather. Males can have one or two copies. Females can only ever have 1 copy.
Here is a double-barred male

(not my picture)
In other countries, darker males are standard and thus produce single barred males. These don't breed true so they're not desirable here.

(not my picture)
Finally, a barred Plymouth Rock hen with single barring.

(not my picture)

 

[Egghead_Jr]

I've not heard and don't quite believe single barred males are desired in other countries.

I'm inclined to think this is a perpetuated misnomer attempting to describe why some males are dark and look like hens when the double barring should make them look much whiter.

How that is actually achieved is keeping a separate male line that is perpetuated with dark hens. There are pullet lines and cockerel lines and some breeders running both lines separately to have show quality cocks and hens. Barred birds benefit from this double mating system as the standard calls for the males to look similar to hens, and we find it more pleasing to the eye.

Double barring by nature will lead to wider white bars that make the males look lighter than the females. It has to be kept in check by strict selection of breeders or keeping a cockerel line to produce show quality cocks and the pullets of that line would not be of correct pattern.

 

[Medodge]

Thank you both very much. The pictures were a great plus.