Droopy Ears Rabbitry

Breeder of Mini Lop Rabbits in Perth, WA

Rabbit Genetics

I have found gaining knowledge and using rabbit genetics fascinating.

The more I knew the more I wanted to know.

 

So I decided to have a section on my website about rabbit colour genetics

for those who are interested to read

and also to help myself learn more along the way!

 

I hope you will enjoy reading it.

 

Rabbit Genetics
by
Annelize Jensen
 
written February 2011
 

 

Rabbit genetics

A new world open to us as breeders once we gain more knowledge of rabbit genetics.

 

We can not only make better breeding choices but most of all we can breed with a purpose. We can predict with more accuracy what coat colours can be expected from a certain mating.

A rabbit’s coat colour is mainly determined by just 5 basic genes. The genes are identified as A, B, C, D and E.

These are the 5 basic genes:

A:            Agouti hair shaft pattern (or not)

B:            Black (or chocolate)

C:            Complete colour (or shaded, or albino)

D:            Dense (or dilute) colour

E:             Extension of colour (or its limitation or elimination)

 

I will examine each of these in more detail but first a few terms and concepts to understand.

 

The DNA strand (A, B, C, D, E) are called a rabbits genotype. It is basically the list of all the colour genes the rabbit has.

 

Each parent donates one of each type of gene to the kits in the litter. In other words the kits inherit two of each gene.

Two genes from each parent are referred to as a locus, “AA”, “Bb” or “B_ “etc.

Each kit will then have two genes from the A locus, two from the B locus etc.

Dominant genes are the colour you can visually see. They are always written in capital letters.

You cannot know by looking at the rabbit what the second code letter of the rabbit is.

The second letter can be a dominant gene or a recessive gene, (meaning less dominant)

Recessive genes are visually not expressed, but are simply carried to be passed on to the offspring of the rabbit. The letter for the recessive gene is always written in lower case.

When a rabbit’s coat colour genetics is not fully known then

a _ underscore is used as a “place maker” in the spot where the second letter should be.

An example would be A_B_C_D_E_, where only the 5 dominant genes are known. All the five other genes are unknown therefore and marked with an underscore instead.

O  Remember that the 5 unknown genes can be either dominant or recessive genes.

A rabbit can have two identical gene copies like “AA”, this is called homozygous (homo = same).

A rabbit homozygous dominant at all 5 loci (multiple of locus) would have a genetic code that reads: AABBCCDDEE

A rabbit that carries two different gene copies at the locus is called heterozygous (hetro = different).

A rabbit heterozygous at all 5 loci would have a genetic code that reads: AaBbCcDdEe

Remember that the upper case letters signifies a dominant gene whereas the lower case letters signifies a recessive gene.

Now we can get back to the 5 basic genes of rabbits coat colour genetics.

 

The A locus

The A locus determines the basic pattern of the hair shaft of the rabbit without influencing the actual colour.  

 

There are 3 possible genes in the A locus.

They are listed below in order of dominance; the most dominant gene is listed first, second most dominant listed second and so on.

A =           Agouti (chestnut, chin, red, etc.) (The most dominant)

At =          Tan (otter and marten) (the 2nd most dominant)

a =           Self (black, blue, chocolate, lilac) (the least dominant)

 

A = Agouti (banded hair shaft)

”A” is the agouti gene, all agouti rabbits have to have at least one of the “a” genes. If they carry two of the genes (AA) then they are homozygous (pure). Meaning they can produce no other colour rabbit but the agouti colour. 

An agouti rabbit have tan, white or fawn marking on the belly, underside of the tail, inside of the feet and legs, inside the ears and nostrils, around the eyes and in the shape of a triangle at the nape of the neck. The fur on the body has rings of colour when blown into the coat. A grey or dove-grey ring at the skin is noticeable. Looking closely at its fur you can see that it is made up of 3 to 5 b and of colour. The Hair closest to the skin is gray. This is followed by yellow and yellow followed by black on the tips of the fur.

The agouti gene can carry the tan pattern (at)  or the non-agouti (self) gene (a). The agouti gene is then referred to as heterozygous. Meaning it is not pure agouti gene. For example Aa is not a pure agouti gene.

 
At = Tan pattern

The tan pattern creates the colouring that is seen on otters and foxes. The tan pattern also creates the silver ticking that is seen in martens.

The tan pattern have (like the agouti) tan, white or fawn markings on the belly, underside of the tail, inside of the feet and legs, inside the ears and nostrils, around the eyes and in the shape of a triangle at the nape of the neck. However, the body does not have the different coloured rings when you blow into the coat.

 

  •  The tan pattern is recessive to the Agouti gene but dominant to the self-gene.

 

A tan pattern rabbit can carry ‘’at’’, ‘’a’’ or both but never the ‘’A’’ gene for Agouti (because it is recessive to the agouti gene).

 

a = Self pattern

All self-rabbits have to carry two non-agouti genes. “a” is the recessive gene in the A series and a recessive gene cannot carry a gene that is dominant to it.

Self-coloured rabbits do not have any of the agouti or tan markings nor do they have a banded hair shaft. Each hair is a solid colour making the rabbit look all the same. The under colour of the coat is a bit lighter. For example the under colour of a black is slight blue and the under colour of a chocolate is dove grey.

When two self-rabbits (aa) are bred together they can never produce an agouti or a tan. A self-coloured rabbit are recessive to an agouti and a tan rabbit. A self-coloured rabbit must carry ‘’aa’’ in the A locus.


B locus

This "letter" “B” tell us how intense the colouring of the rabbits fur is.

There are only two genes in this set so there are only 3 possible
combinations ‘’BB’’, ‘’Bb’’ and ‘’bb’’.
The ‘’B’’ - black gene being the most dominant and the ‘’b’’ chocolate the recessive.


B = Black - The rabbit is black based, meaning the base colour is black or blue, blue being the dilute of black. Black or blue are the dominant colour.


‘’b’’ = brown – The rabbit is brown meaning chocolate or lilac. Lilac being the dilute of Chocolate. A rabbit must have one gene from each parent to be a chocolate colour. In other words chocolate have to be the gene and they have to be homozygous for chocolate.

Therefore a black rabbit can carry chocolate, “Bb” the ‘’b’’ gene, which would,
appears like the ‘’Bb’’, but a chocolate rabbit cannot carry black (bB).
A chocolate rabbit will always be ‘’bb’’. A recessive gene cannot carry a
dominant gene.

In other words two chocolate rabbits cannot produce any offspring that are black or blue.

If you breed two black rabbits and there are chocolate in the litter
then the B series would be Bb in order to produce a chocolate both
parents must be carrying the b-gene.  Chocolate based rabbits are ‘’bb’’ and
the offspring must get one ‘’b’’ from each parent.

C Locus

The C locus controls the amount of pigment in the hair shaft.

“C” is the most dominant gene,

“’c(chd)” is the second most dominant gene,

“c(chl)” is the third most dominant gene,

“c(h)”is the fourth most dominant gene, and

“c” is the most recessive gene (least dominant)

 

There are 5 different C Locus possibilities and some are dominant.

The 5 genes for the C locus are:

C = full colour gene. The full colour gene creates the one colour that we see in blacks, blues, chocolate and lilac.

cchd = dark chinchilla. This gene removes all red, orange, yellow and fawn pigment from the coat, leaving white.

cchl = light chinchilla.All the yellow is removed and the strength of the black is weakened.

ch = himi (Himalayan) The Himalayan is a pointed rabbit. It is only one step above a ruby eyed white. All the colour has been removed except the points.

cc= ruby eyed white (albino). This rabbit has no colour expression. This means that on the C locus it can only give a c.  It cannot carry any other gene because all other C genes are dominant to it. This gene removes all pigment from the coat and also makes the eyes pink. The pink that is seen is from the blood vessels because the albino gene removes all pigment from the rabbit.

Ruby eyed whites (rew’s) are best to breed only with other rew’s. Unless you know what your rew carries under its coat.

If you decide to test breeding be prepared to have offspring that are not showable and have few uses in a breeding program.

 

D - Locus

The ‘’D’’ locus are referred to as the intensity (dense)  of your rabbits coat colours.

There are only two genes in this set

‘’D’’= Dense (intense) colours being dominant, all dense colours have a corresponding dilute colour.

‘’d’’ = Dilute colours

Black and chocolate are dense (intense) colours whereas blue and lilac colours are controlled by the ‘’d’’.

Dilution, it changes black to blue and change chocolate to lilac. It also changes brown eyes to grey eyes.

 

The rabbit must receive one dilute ‘’d’’ gene from the sire and one dilute ‘’d’’ gene from the dam. This make the offspring rabbits genotype ‘’dd’’
The dominant intense ‘’D’’ has no effect on the black or the brown locus colouring. A dense colour is more dominant and can only produce a dilute colour if it carries the dilute gene “Dd” and is paired with another rabbit that is either a dilute colour ‘’dd” or a dense colour carrying dilute “D’’.

 

A dense coloured rabbit cannot produce a dilute colour if it doesn’t carry the dilutions gene even when mated with a dilute colour rabbit. Each rabbit MUST carry dilute to produce dilute coloured offspring.

 

Some dilute colours

Lilac is the dilute of Chocolate,

Opal is the dilute of agouti,

Fawn is the dilute of orange

Squirrel is the dilute of black chin,

Lilac chinchilla is the dilute of chocolate chinchilla

Lynx (lilac agouti) is the dilute of chocolate agouti

Lilac tort is the dilute of Chocolate torte

So black and chocolate rabbits will be ‘’D_” and blue and lilac rabbits will be ‘’dd’’

 

 

E – Locus

The E locus are the extension of colour.

There are 4 genes in the E locus.

“Es” = The steal rabbit. The most dominant.

“ E” = The full extension colouring. The 2nd most dominant.

“ej” = The brindle found in Harlequins. Second most dominant.

“ee” = The most recessive , the non-extension colouring as well as most recessive (least dominant).

 

In order of dominance for the E locus is

 ‘’Es’’ = Are called the steel gene it is also the most dominant gene in the E locus. The steel gene is solid coloured rabbits with hairs are that are ticked with either gold or silver tipping.

‘’E’’ = This is the full extension colouring like in self, agouti’s, otters and martens. It is the second most dominant gene.  Most colours have this gene. Some of the colours that have this gene are black, blue, chocolate, lilac, chestnut agouti, opal, otter, silver marten, lynx, chestnut agouti and cinnamon agouti.

‘’ej’’ = brindle, this is your harlequin marked rabbits, Japanese and magpie. It is the 3rd most dominant gene.  This gene makes the orange and the colour (black, blue, chocolate or lilac) separate =onto different hairs and into bands. When it is a broken colour pattern then it is called a Tricolour.

Common sense leads us to think that if you have a Japanese harlequin and want to improve the markings, you mate it with a better marked Japanese harlequin. However if you mate your Japanese harlequin with an agouti you can improve your markings due to the orange colouring in the agouti and because the genetic code are very like the Japanese harlequin’s genetic code.

The agouti’s genetic code:  A_B_C_D_E_W_

The Japanese harlequin’s genetic code:  A_B_C_D_ej_W_

 

The Japanese brindling gene is responsible for magpies harlies and tri’s, it basically creates a striped/block effect.

The difference you will notice from Harlie to magpie is what is going on with the C locus. The ‘’cchd’’ = “the dark chin gene” strips away the orange colouring and replaces it with white.

Here you can see why you can use the chinchilla to enhance the colouring of your magpies, because of the genetic codes that are alike.

The Chinchilla’s genetic code:  A_B_c(chd)_D_E_W_

The magpie’s genetic code: A_B_c(chd)_D_E_W_

 

Do not introduce the harlequin genes into your normal lines it can be like playing with fire and I would definitely not suggest it. You will struggle for generations to get rid of the harlie markings.

The ‘’ee’’is  the most recessive, the non – extension.  There is no colour extension, leaving only what would be  seen in the coat. The colour it reduces is black, blue, chocolate, lilac, seal, sable or smoke pearl.

 

The broken gene:

This gene represents the spotted rabbits.

En = broken colour

en = solid colour

In order of dominance:

EnEn = Charlie or lightly marked broken with colour on the ears, on the nose and sparingly on the body.

enen =  It is the broken rabbit with roughly even distribution of colour and white.

enen = Solid colour with no white areas.

 

  • This is the only gene where you know the second gene in the series by looking at the animal.

 

 

 

  •  Breeding two solid rabbits will produce two solid rabbits only.

 

Since EnEn is dominant and enen is recessive, then if you breed them together you will get 100% brokens. The charlie rabbit can only give En and the solid rabbit can only give en.

However you can breed your Charlie (en) with a self coloured (black, blue, chocolate and lilac) and will get beautiful broken/butterflies.

Charlie rabbits are not showable. Although they can still be useful in certain breeding programs. Keeping your best typed Charlie rabbit can be beneficial to a broken breeding program.

 

The vienna gene:

V = normal coloured fur

v = vienna marked

VV = normal coloured rabbit

Vv = mismarked vienna carrier

vv = blue eye whites

vm = vienna marked, the vienna marked rabbit his white markings present usually on the face, feet or nose area. It can cause white toenails and disqualification in rabbit shows.

 

Do not breed vienna marked or blue eye whites into your other colours unless you completely understand the gene cause the gene can cause generations of problems.

 

The W locus

The ‘’w’’ represents the middle yellow – white band locus and works with the agouti gene. The genes are:

W = normal width of yellow band (agouti band colour)

ww = doubles yellow band width, otters become tan.

 

This is the order of dominance for each gene:

A- agouti
at- tan patter (otter and marten)
a- self (black, chocolate, blue, lilac)


B- black
b- chocolate

C- full color (this would be torts, selfs, most agoutis)
chd- Chinchilla dark
chl- shaded
ch- himi
c- albino (REW)

D- dense (black and chocolate based animals)
d- dilute (blue and lilac based animals)

E- Full extension (i.e. black)
e- non extension (i.e tort, sable point)

En- Broken
en- Solid
En_En- Charlie

Additional genes:

Es- Steel
Ej- Japanese (harlequin and tri-color)
v- Vienna

w- rufus 


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