Chooks & Genetics

Which sex,which type of comb,how many toes,the colour of the bird’s shank,the pattern / colour in the feathers, are all determined by the information that is stored in the bird’s ‘genes’

The genes are located on pairs of ‘chromosomes’

(In chickens there are 39 pairs of chromosomes)

One of these pairs is called the ‘sex chromosomes’

In a male bird the ‘sex chromosomes’ are similar.

In a female bird one of the ‘sex chromosomes’ is almost empty

Female bird

Male bird

Most genes have two parts eg.

The gene for whether or not a bird has a rose comb

‘R’ is the symbol for the rose comb formthis bird’s genotype is R / R

The gene for whether or not a bird has mottled plumage

‘mo’ is the symbol for the mottled formthis bird’s genotype is Mo+ /

mo

The only genes that have one part are those that are on the females sex chromosomes

The gene for whether the bird is based on silver or gold S / -

The gene for whether the bird is barred or not B / -

The gene for whether the bird has an inhibitor of melanin or not Id / -

All genes that affect the appearance of the bird usually have two or more different forms;

one form from the original (red) jungle fowls (RJF), marked with a ‘+’ after the symbol, called ‘wildtype’

Male RJFe+/e+ s+/s+

Female RJFe+/e+ s+/-

ALL the other forms have arisen from mutations

eg. for type of comb there are different forms

for single comb, which is the wildtyper + / r + p + / p +

for rose comb, ‘R’ is the formR / R p + / p +

for pea comb, ‘P’is the formr + / r + P / P

Some forms of a gene are ‘dominant’ to other ‘recessive’ forms

the dominant form’s symbol will be capitalised

eg. rose comb R is dominant to wildtype r+

a bird will have a rose comb with R/R or R/r+

R/R is also written ‘ hom R ‘R/r+ is also written ‘ het R ‘

r+/r+ is also written ‘ hom R ‘ single (wildtype) comb

The most important gene for the plumage is the ‘ e – gene ’

There are five forms, in usual order of dominance

E ‘extended black’E^R ‘birchen’e+ ‘wildtype’e^b ‘brown’e^Wh ‘wheaten’

E Ancona, black mottled Langshan, AustralianAustralorp Leghorn, White Plymouth Rock, Barred

E^R Campine, gold & silver Hamburg, silver spangledModern Game, brown-red Sebrights, gold & silver

e+ Dorking, silver-grey all Jungle Fowls Leghorn, pullet-breeding (light) brownModern Game, ginger Old English Game, ginger

e^b Barnevelder, double-laced Hamburg, gold spangledLeghorn, cockerel-breeding (dark) brown Silkie, whitemost Wyandottes

e^Wh Faverolle, salmon New Hampshire RIR Sussex, light

The next most important gene for the plumage is the ‘ Silver – gold gene ’

Silver S(dominant)

gold s+(recessive)

Ancona, Black Mottled (white/dark).................E/E (or ER/ER) (S/S S/-) Australian Langshan, Black (red) .......................... E/E s+/s+ (s+/-) Australorp, Black (red) ............................ E/E s+/s+ (s+/-)

Barnevelder, Double-laced (red).............. eb/eb s+/s+ (s+/-)

Campine, Gold (white).............................. ER/ER s+/s+ (s+/-) Campine, Silver (white)............................... ER/ER S/S (S/-)

Dorking, Silver Grey (red) ...................... e+/e+ S/S (S/-) Faverolle, Salmon (red) ......................... eWh/eWh S/S (S/-)

Hamburg, Gold Spangled (white) ............... eb/eb s+/s+ (s+/-) Hamburg, Silver Spangled (white)............. ER/ER or eb/eb S/S (S/-)

ISA Brown (red)..................................... eWh/eWh s+/s+ (s+/-)

Japanese Bantam, Black................ ER/ER Id/Id (Id/-)

Jungle Fowl, Red........................... e+/e+ all wildtype

Leghorn, Brown (CB) (dark)........... eb/eb s+/s+ (s+/-) Leghorn, Brown (PB) (light)........... e+/e+ s+/s+ (s+/-) Leghorn, White.............................. E / E S/S (S/-) I / I

Modern Game, Birchen................... ER/ER S/S (S/-) )Modern Game, Brown Red....................ER/ER s+/s+ (s+/-)Modern Game, Ginger........................e+/e+ s+/s+ (s+/-) New Hampshire................................... eWh/eWh s+/s+ (s+/-) Old English Game, Ginger................... e+/e+ s+/s+ (s+/-) Old English Game, Black Breasted Red, Dark Leg......... e+/e+ s+/s+

(s+/-)

Plymouth Rock, Dark Barred .......... E/E S/S (S/-) B/B (B/-) K/K (K/-) Rhode Island Red, Single Comb...(exhibition)... eWh/eWh s+/s+ (s+/-)

Sebright Bantam, Gold..................... ER/ER s+/s+ (s+/-) Sebright Bantam, Silver.................... ER/ER S/S (S/-)

Silkie,White...................................... eb/eb s+/s+ (s+/-) or S/S (S/-)

Sussex, Buff...................................... eWh/eWh s+/s+ (s+/-) Sussex, Light.................................... eWh/eWh S/S (S/-)

Welsummer, Partridge........................ e+/e+ s+/s+ (s+/-)

Wyandotte, Black (CB)........................ ER/eb Wyandotte, Black (PB)........................ eb/eb Wyandotte, Blue Laced Gold.............. eb/eb s+/s+ (s+/-) Wyandotte, Blue Laced Red............... eb/eb s+/s+ (s+/-) Wyandotte, Gold laced...................... eb/eb s+/s+ (s+/-) Wyandotte, Silver Laced (CB)......... eb/eb S/S (S/-)

Autosomal Genes

Extended E Birchen E^R Wheaten e^Wh Wildtype e+ Brown eb

Co co+ Columbian eg. Light Sussex, New Hampshire

Ml ml+ Melanotic eg. Black Australorps, Black Langshans

Pg pg+ Pattern

Mh mh+ Mahoganyeg. Rhode Island Reds

ig Ig+ Inhibitor of Gold (when homozygous) eg. Cream Legbar, true-breeding Golden Duckwing Leghorn

I i+ Dominant White eg. White Leghorn Bl bl+ Blue (when heterozygous) eg. Blue anything

mo Mo+ Mottled (when homozygous) eg. Ancona

c C+ Recessive White (when homozygous) eg. Light Sussex, White Langshans

R r+ Rose Comb eg. Wyandottes, Hamburgs

P p+Pea Comb

Sex Chromosome Genes

S s+ Silver / Gold (when homozygous) eg. Silver-Grey Dorkings, Partridge Wyandottes

B b+Barring eg. Dark & Light Barred Plymouth Rocks