Cuckoo – Double Bar and Single Bar factor - an easy and not so easy explanation

by the Cuckoo Stud

This is my own work and is written resulting from years of working with the Cuckoo Orpingtons and a select few other breeds in Cuckoo 
no comment is made to other breeds’ Cuckoo colour/pattern as I have little or no knowledge of breeds other than those I work with

Working with double as opposed to single bar factor birds gives different outcomes.

Mating Cuckoo to Black

Double bar = in the males = the lighter colour between the dark is wider (sometimes considerably wider) than the dark. 
When considerably wider it gives a silvery appearance in some birds, but is NOT Silver Cuckoo.
There is no such thing as a Silver Cuckoo in Australia = it is a double bar bird = do not be conned.
These overly light, silvery males are not suitable for exhibition as they do not meet the APS Standard for perfection.

Single bar = the lighter colour between the dark is of the same width or narrower than the dark.
This is the colour favoured for exhibition in the males.

Double bar factor roosters when mated to Black hens = the outcome is 95% to100% Cuckoo pullets and 100% cockerels with the lighter males also being double bar. It is rare but some Black females do hatch from this mating.
Of these Black females 50% will carry Cuckoo.

Single bar factor roosters when mated to Black hens predominantly gives offspring equalling 99% of the males are Cuckoo (with the rare Black male) to a 20% Cuckoo / 80% Black female ratio, on average. Any Cuckoo females from this mating are valuable to produce more female Cuckoo. These females display slightly darker than the males. 
50% to 100% of the Blacks carry Cuckoo and can be used to deepen the colour in a Cuckoo line that displays poor depth of colour. However these Black often change leg and eye colour in their Cuckoo offspring, requiring careful selective breeding to reduce this problem = by carefully selecting those Black that have mottled legs and/or reddish brown eyes.
The reddish brown eyes indicate cross colour bred birds.

Note that it is not recommended that these Black carrying Cuckoo be used in Black or Blue or Splash matings as the Cuckoo will come through, if not in the immediate, in future generations. (this has been proven in my backyard over 20+yrs of experimenting since acquiring Blue and Splash). However if one wants to develop a new line of Cuckoo these Black are a valuable tool.



A less simplistic explanation

Cuckoo and Barring are basically the same gene, it is believed to be pivotal on if the pattern is on fast or slow growing feathers. Some may have noted juvenile ‘Cuckoo’ birds displaying ‘barring’ that blurs to Cuckoo with age. These are not Barred birds, just slow to feather out.

Cuckoo is a sex linked gene, meaning the male may have two, and be pure, B/B, for Cuckoo (will look Cuckoo) ; these are almost always a lighter colour, with the light bars wider than the dark.

Or he will have just one B/b+ and be impure (will also look Cuckoo) ; these will display a darker colour with narrow light bars.

Mating a B/B (two doses, homozygous, or double bar) male to a Black b+/-  hen will give Cuckoo chicks as they are either B/b+ males or B/- females.

However if the male is an impure Cuckoo B/b+ (single bar) mated to a b+/- Black hen the chicks can be Cuckoo B/b+ males; b+/b+ Black males; B/- Cuckoo hens or b+/- Black hens.

Mating a B/B (double bar) male to a B/- Cuckoo hen will give all Cuckoo offspring – unless the male is actually an impure single bar but displays as double bar.

Mating a B/b+ (one dose, heterozygous, or single bar) male to a B/- Cuckoo hen will result in predominantly Cuckoo offspring with the remainder being Black of either sex (carrying Cuckoo)

Females can only ever have one dose, this is why double barring is sex linked.


Mating Cuckoo to White

commenting only from personal experience with the WA Whites acquired

Double bar factor Cuckoo rooster mated to White hens = on average 55% hatched Cuckoo (both sexes). Most displayed a poor pattern that did not extend the length of the feather.
About 10% to 15% of the females were White with black or Cuckoo flecking = these were grown out and mated back to Cuckoo.
The remaining birds displayed as White (both sexes).
When either the White or flecked birds were mated brother sister they produced 90% to 100% Cuckoo, with the balance either White or White with flecking.

Single bar factor Cuckoo rooster mated to White hens = about 35% of the males hatched Cuckoo, with a higher percentage of the females White displaying flecking.
With either these White or flecked offspring when mated brother sister 80% to 90% Cuckoo (both sexes), displaying a better pattern than the Double bar offspring, and 10% to 20% White or White with flecking.

With both the Double and Single bar factor Cuckoo/White cross all that hatched White were a very bright crisp White but they all carried Cuckoo when test mated back to White.
I found the ones with the flecking to be the better choice to mate to Cuckoo, as they tended to throw a higher percentage of Cuckoo when mated back to Cuckoo.

The Cuckoo/White mating keeps the beak and eyes the correct colour as the White has the same as the Cuckoo in this regard.
Note that the legs on Cuckoo are often white skinned with mottling as per the Cuckoo gene, this is allowed as per APS Edition 2.



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