Genetics Mini-Series Article #10
Shank color genetics in chickens is anything but straight-forward. Traits believed to be prevailing a hundred ago are now considered recessive. Traits which appear to be governed by one gene nowadays appear to be one gene with five different venue. Some believe shank color to be controlled by two traits, others by three, and still others by four, and all agree that the construction of these traits is affected by a overplus of feather genes and yet-unidentified modifiers. thus, with that in mind, I ’ ll present my best pang at a working theory and encourage far research to those interest in shank color .
Reading: GMS10: Skin and Shank Color
Skin Color
Some report skin color ( yellow or white ) as being restricted to the epidermis, or top layer of peel. Others say that peel color is salute in both the epidermis and dermis ( deep layers of skin ). You can frequently see a red tinge in accession to the skin color. This is much from increased lineage flow due to hormones, most noticeable in a cock ’ mho shanks during mating season. A red tone, sometimes called horn, can besides be a secondary effect of red or golden feather .
Yellow skin
yellow skin is recessionary ( w ). The yellow paint is from carotenoids which are consumed by the chicken. A diet rich in carotenoids ( frequently in the shape of greens and corn ) will enhance the yellow pigmentation. The chicken pigmentation in a hen ’ south shanks will fade throughout her laying hertz as nutrients are pulled into her eggs from the reserves in her consistency. yellow pigmentation will besides fade with age .
White skin
White skin is dominant and is the barbarian type ( W+ ). White skin is characterized by a miss of chicken pigmentation .
Dermal Melanin
Dermal melanin is a black paint in the deeper layers of skin. The presence of cutaneous melanin is recessive and is the angry type ( id+ ). The absence of cuticular melanin is dominant ( Id ). Dermal melanin is a sex-linked gene. Males carry two copies and females carry one. Dermal melanin itself is controlled by five different alleles which affect its formulation and do not seem to be entirely understood ( Id, international development association, idc, idM, id+ ; see here ). Dermal melanin comes in lento and is normally not present in chicks ( excepting those with birch or extend black, explained more below ). The best time to identify the presence of dermal melanin is from 8 to 16 weeks of old age as cuticular melanin can fade over fourth dimension .
Factors inhibiting dermal melanin
Certain feather patterns inhibit the formula of cuticular melanin and may reduce or hide the presence of the id gene wholly. Barring ( B ) is one of these genes. Because banish is besides sex-linked, males with two copies of the barring gene ( B/B ) will probably not show dermal melanin at all while females of the lapp line ( B/- ) will show some cuticular melanin .
other factors inhibiting the expression of cuticular melanin to varying extents include : mottle ( Mo ), dominant white ( I ), recessionary white ( deoxycytidine monophosphate ), bluing and spatter ( Bl ), gold dilute ( Di ), flatware ( S ), and wheaten ( EWh ). A fall undercolor in the feather, visible in the ‘ bagatelle, ’ can be discernible where feather genes dilute cuticular melanin.
Factors enhancing dermal melanin
Base colors which extend areas of eumelanin tend to extend the black paint into the shanks a well. Some people call this cuticular melanin, but others seem to think that this melanin is actually spread into the epidermis preferably than the dermis. Base colors which enhance cutaneous melanin include extended black ( E ) and birch ( EB ) to a lesser extent .
Other melanizers
other genes can cause a blue pigment in the shanks, such as the dominant Fibromelanosis ( Fm ) gene used to darken the skin of Silkies .
Resulting Genotypes and Phenotypes
This chart describes stage color very generally, using only the W-gene, the Id-gene, and a bit of information from the E-series alleles .
These are common cannon colors as they are sometimes called. Dusky white, dusky yellow, and straw are not normally used terms. Dusky blank might be characterized as plainly white or slate, dusky yellow as willow, and chaff as yellow or light scandalmongering .
besides see GMS Supplement # 2 : Skin Color Punnett Squares and Test Crossing for visuals of the inheritance of white and yellow hide and a discussion of how to breed out unwanted recessionary traits .
Shank Color References and Resources
This is surely not an exhaustive explanation of shank color genetics and may not even be wholly accurate. hera are the resources I used which may be a great springboard for far probe :
