crossing two barred breeds getting a surprize

[tadkerson]

You have two male birds. See if the single combed bird lays eggs.

Tim

 

[centrarchid]

Quote:
I already culled out single combed birds. Group of interest made up of three males and two females. I think still 60 days away from egg production if California grey makes the lay early like a leghorn. Another cohort should be hatching any day and a third will be in just over 21 days. This is being repeated since so many being culled owing to comb issue. Something is not right about overal coloration of doms x California gray. Maybe contrast between light and dark bars too low.

Tim, I can almost see you over there!

 

[tadkerson]

The only other possibility ( that I can think of) is the effect of heterozygous E locus alleles. Barring works great on extended black alleles. But you start having problems with barring when you have the expression on other E locus alleles. The tails and wings are the first areas to show the heterozygous effect. This has been my anecdotal experience.

The extended black allele is a constitutive intramembrane protein ( MCR-1 receptor) that signals all the time- it does not need melanocortin to bind to it in order to signal the production of eumelanin (black pigment). Other allleles (wheaten, wild type) must have a binding agent to generate a signal to produce eumelanin. This need to have a binding agent may be the reason for the slower production of eumelanin and the smeared barring. If you have an allele that is ready to fire the moment the barring gene stops interrupting the signal you get a crisp line between barring and black. Just my two cents.


Here is a reference: Warning lots of biochemistry

Eur J Biochem. 2003 Apr;270(7):1441-9.
Association of feather colour with constitutively active melanocortin 1 receptors in chicken.
Ling MK, Lagerström MC, Fredriksson R, Okimoto R, Mundy NI, Takeuchi S, Schiöth HB.

Tim

 

[centrarchid]

Thanks Tim,

It does appear a second barring allele is at play although text saying birds with nearly is an exageration. With a single operating locus as in the females, the bar intervals are tighter and with lesser contrast than between light and dark. On average the color is lighter than on the standard barred. The males with two operating loci; one with the standard barred allele and other with "tighter" version appear intermediate between homozygous males of same age. The lighter allele will be selected against.