Poultry Genetics
An Easy Guide to Genetics 101
Skip to:
The Basics (Dominant, Co-Dominant, Recessive, Hetero/Homozygous, etc)
E Locust (Solid, Birchen, Duckwing, Partridge, Wheaten, etc)
Pattern Genes (Columbian, Blacktail/Ginger, Patterning, Melanotic)
BBS (Blue/Black/Splash)
Silver (Silver, Golden, Gold/Red)
Barring, Cuckoo & Sexlink
White (Dominant & Recessive)
Mottling
Lavender
Chocolate (Dun/Khaki)
Less Common Colors (Lemon/Cream, Mahogany, Dilute, Charcoal, etc)
Egg Colors (White, Cream, Tan, Brown, Olive, Green & Blue)
Fibromelanism & Gypsy Face
Longtail Complex
Vaulting & Crests
Comb Types
Shank & Foot Feathering
Number of Toes
Other Considerations
The Basics
(Dominant, Co-Dominant, Recessive, Hetero/Homozygous, etc)
​​
Homozygous & Heterozygous
Homozygous refers to having both genes in a set. Every gene comes in a pairing of two. For example, ER/ER or S/S. Heterozygous means that only one of the two genes in a set are present - for example, ER/eb or S/s+. Heterozygous birds may or may not pass on their visual genetics to their chicks - they may instead pass on the more recessive, non-visually expressed gene.
​
Dominance in Genetics
All genes are either Dominant, co-Dominant, or Recessive.
Dominant genes are represented with a capitol letter, and need only one gene of the pair to fully express. Examples - E (Extended Black), Di (Dilute)
​
Co-Dominant genes are also represented with a capitol letter, but have different effects depending on whether there are one or two genes present in the set. For example, bl (Blue) expresses as a bluish-gray when one gene is present, but presents as white with a smattering of bluish-gray feathers when homozygous. Similarly, S (Silver) turns all gold feathers white when homozygous, but when missing a gene, the hackles, saddles, and wing bars on roosters will show a yellowish tarnish.
​
Recessive genes are represented with a lower-case letter, and need both genes of the set to visually express. Examples of this are lav (Lavender) and h (Silkied). When heterozygous, there is no visual difference from a bird with the genes absent.​
​
Allele
This is the term for individual genes. Each allele comes in a pair, described above in homozygous and heterozygous. Allele pairs for specific genes are located on specific locations on the genome, called a Locus.
​
Locus
A Locus is a specific location on the genome where Alleles are located. Some genes share a locus, which means that the bird cannot be both at once. For example, the E Locus is the location of the base pattern genes - a bird can either be ER (Birchen) or eWh (Wheaten) but cannot be both; a bird that has one copy of each will visually present as the more dominant gene. Another example is the Dominant White allele complex - a bird could be either I (Dominant White), or Id (Khaki/Dun), but not both; an I/Id bird would present as Dominant White.
Base Color vs Secondary Color
The base color of a bird is the background color. With no additional modifier genes, this is solid black, as seen with E (Extended Black). Genes that modify just the base color are Choc (Chocolate) and Bl (Blue).
The secondary color is what is shown when patterned E Alleles are present. In males, this shows on the hackles, saddles, and wings. In females, coverage can range from just the hackles to full body, depending on the E Allele. With no additional modifiers, this color is Gold (visually, orange-red). Genes that change just the secondary color are S (Silver), Di (Dilute), Mh (Mahogany), Ig (Inhibitor of Gold), and Cb (Champagneblond).
​
Genes that change the color of both the Base and Secondary are homozygous Bl (Splash), the Dominant White complex, c (Recessive White), and lav (Lavender).
​
Some pattern genes effect the placement of base and secondary color, such as Db (Darkbrown/Ginger), Ml (Melanotic), the Laced and Spangled complexes, Db+Co (Columbian), Mo (Mottled) and B (Barred).
E Locus
(Solid, Birchen, Duckwing, Partridge, Wheaten, etc)
​
The base pattern!
​
Order of Dominance*:
E(Extended Black)>ER(Birchen)>e+(Wild Type/Duckwing)>eWh (Wheaten)>eb(Partridge)>ey(Recessive Wheaten)>ebc(Buttercup)
​
*Some of these genes are incompletely dominant to others, see details.
​
​
E - Extended Black
​​
The most dominant of the base patterns. Presents as an un-patterned bird of base color (black, blue, etc). It causes an increased amount of eumelanin, or black feather pigment. However, a lack of other melanizers can present in males as hackle and saddle red leakage and in females as minimal red leakage on hackles. These birds may be confused as ER Birchen but note the lack of color on wing bars and breast.
​
Chick Color:
Solid base colored or with a slightly lighter belly. Some breeds present with cream in the head and face, which disappears at first molt. Barred chicks present with a white dot on the head, and mottled chicks will have a white tuxedo pattern.
​
Genes that visually effect E:
Barring, Chocolate, Dominant White, Blue, Mottling, Recessive White, Lavender
​Note that many other genes may effect leakage color, such as Silver, Mahogany, etc.
​
Breeding with homozygous E:​
E x E - 100% Extended Black
E x ER - 100% Extended Black, with hidden Birchen
E x e+ - 100% Extended Black, with hidden Wild Type
E x eWh - 100% Extended Black, with hidden Wheaten
E x eb - 100% Extended Black, with hidden Partridge
E x ey - 100% Extended Black, with hidden Recessive Wheaten
E x ebc - 100% Extended Black, with hidden Buttercup
​​
​
ER - Birchen
​​
The second in line of dominance on the E Locus. Birchen presents as a solid black ground color with a secondary color on the hackles, saddles, and wing bars of roosters and lacing on the breast of both sexes. Selection within a line can produce birds with more or less breast pattern; it is possible for unknown genes to be in effect here. A notable difference between Birchen, which is also called Crowwing, and all other patterned E alleles, is the distinct lack of secondary color on the wing triangle (the primary and secondary flight feathers).
​
Note: While the term 'Birchen' is commonly used to refer to a silver birchen bird, ER Birchen itself is a base pattern gene, and can be in a variety of colors and patterns. Gold Birchen is often called 'Red-Brown'.
​
Chick Color:
​Birchen chicks are, in general, tuxedo-patterned. However, the Db Darkbrown/Ginger gene can produce a solid color chick with shading on the head and back.
​
Genes that visually effect ER:​
The pattern gene produces further detailing and extension of the breast lacing, while the full lacing gene set (see Lacing) produces a fully laced bird. Additional melanizers such as Ch (Charcoal) and Ml (Melanotic) can produce an almost- or fully-solid bird, leaving room for confusion with Extended Black. All color and pattern genes can be visually expressed on Birchen.
​
Breeding with homozygous ER:​
ER x ER - 100% Birchen
ER x E - 100% Extended Black, with hidden Birchen
ER x e+ - 100% Birchen, with hidden Wild Type
ER x eWh - 100% Birchen, with hidden Wheaten
ER x eb - 100% Birchen, with hidden Partridge
ER x ey - 100% Birchen, with hidden Recessive Wheaten
ER x ebc - 100% Birchen, with hidden Buttercup
​
​
e+ - Wild Type / Duckwing
​​
Wild Type is the ancestral color for chickens. It is also referred to as Duckwing (due to the bluish sheen on silver e+ birds), as well as Black Breasted Red. Unlike Birchen, Wild Type roosters have secondary color on their wing triangles, but are otherwise similar. Wild type roosters are very difficult to tell apart from eb (Partridge). However, Wild Type hens are distinct - with a medium brown ground color with slight patterning, a warmer 'salmon' breast, gold and black patterned hackles, and a black tail.
​​
​
Chick Color:
Wild Type chicks are brown, chipmunk striped with a black eyeline.
​
Genes that visually effect e+:​
Unlike Birchen, the Laced complex cannot produce a properly laced bird on e+. All other color and pattern genes can be visually expressed on Wild Type.
​
Breeding with homozygous e+:​
e+ x e+ - 100% Wild Type
e+ x E - 100% Extended Black, with hidden Wild Type
e+ x ER - 100% Birchen, with hidden Wild Type
e+ x eWh - 100% Wild Type, with hidden Wheaten
e+ x eb - 100% Wild Type, with hidden Partridge
e+ x ey - 100% Wild Type, with hidden Recessive Wheaten
e+ x ebc - 100% Wild Type, with hidden Buttercup
​
​
eWh - Dominant Wheaten
​​
Roosters share the same pattern as e+ (Wild Type) and eb (Partridge); however, they have distinctly light under-fluff, especially noticeable where the tail meets the body. Wheaten hens are uniquely light-colored, with a cream body and warm brown hackles and wing triangle, along with warm-brown shading on the shoulders, saddle, and back. Tail feathers are black.
​​
Chick Color:
Solid yellow down with some dark patterning.
​
Genes that visually effect ER:​
The pattern gene produces further detailing and extension of the breast lacing, while the full lacing gene set (see Lacing) produces a fully laced bird. Additional melanizers such as Ch (Charcoal) and Ml (Melanotic) can produce an almost- or fully-solid bird, leaving room for confusion with Extended Black. All color and pattern genes can be visually expressed on Birchen.
​
Breeding with homozygous ER:​
ER x ER - 100% Birchen
ER x E - 100% Extended Black, with hidden Birchen
ER x e+ - 100% Birchen, with hidden Wild Type
ER x eWh - 100% Birchen, with hidden Wheaten
ER x eb - 100% Birchen, with hidden Partridge
ER x ey - 100% Birchen, with hidden Recessive Wheaten
ER x ebc - 100% Birchen, with hidden Buttercup
​
​
​
​
​
​
​
​
​