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Gene B: Black

 
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Genetic terms in cats
Genome of the cat
Dominance of genes
Cat Breeding techniques
Crossing Table 1
Crossing Table 2
Crossing Table 3
Gene A: Agouti
Gene B: Black
Gene C: Full colour
Gene D: Diluted
Gene Dm: Dilute modifier
Gene Fd: Folded ears
Gene I: Inhibitor
Gene L: Shorthair
Gene Mc: Mackerel
Gene O: Orange
Gene S: Piebald spotting
Gene W: White
Gene XY: Sex
Quality Points for Cats

 

Gene B: Black

Gene group B, b, bl

BLACK gene B

Gene B is responsible that the coat colour gets black.
It is dominant over its alleles. Therefore gene B must be present only once to see its expression that the coat colour appears black.

Alleles

CHOCOLATE Gen b

Gene b is recessive to gene B. Your cat must have either bb or bbl that its coat gets chocolate coloured.

Possible gene combinations

BB homozygous black
Bb heterozygous black
chocolate carrier
Bbl heterozygous black
cinnamon carrier
bb homozygous chocolate
bbl heterozygous chocolate
cinnamon carrier
blbl homozygous cinnamon
Note that cinnamon cats are always homozygous for this colour.

CINNAMON Gen bl

Gene bl is recessive to gen b, and of course also to gene B.
That means, a cat must carry gene bl twice (blbl) to show the cinnamon colour on its coat.

 

Where do I find such colours, like cinnamon ?

Black you find in almost all breeds, Persian and Exotic, Maine Coon, Norwegian Forest, British Shorthair, Rex, Oriental, Javanese, etc.
Chocolate you'll find in Persian and Exotic, British Shorthair, Rex, Oriental (called Havanna), Javanese.
In the so called natural breeds, like Maine Coon, Norwegian Forest Cat or European Shorthair chocolate - and consequently also lilac - is not allowed in most federations.
Cinnamon you'll find mainly in Abyssinian (called Sorrel) and Somali, Ocicat, Rex, Oriental and Javanese.
Now breeders have started to breed cinnamon pointed Siamese and Balinese, too.

How can this theoretical knowledge be used for the breeding practice ?

You want to breed chocolate.

Which cats could be used to reach this goal ? How can you detect, if you'll ever get chocolate kittens from your black female ?

Example 1

The easiest way - of course - is to use a chocolate female and a chocolate male. Are you really sure only to get chocolate kittens out of this mating ? I wouldn't.
Let's have a look !
Both the chocolate female and chocolate male can be either homozygous for chocolate (bb) or heterozygous for chocolate (bbl).

Let's take the worst case, both are heterozygous.
  male
b bl
female b bb bbl
bl bbl blbl
You see, you'll get a cinnamon cat, too. Only one cat will be homozygous for chocolate, two will be heterozygous for chocolate like their parents. But you can't see this from outside and your chance, not to keep the homozygous chocolate from the 3 chocolate kittens is 66%.
Only test mating with a cinnamon cat will help you to find out, which chocolate cat you've kept.

 

Example 2

But what to do, if you don't have 2 chocolate cats ?
Your female is black, and you want to know if she can produce chocolate kittens, that means if she carries chocolate (gene b).
It would be wise to mate your female with a chocolate male to find this out easier. Otherwise, if you mate her with a black male, you propabely don't know if the stud male carries chocolate, too.
Let's cross our female with a chocolate male. The genetic fingerprints of our female can be either Bb (she carries chocolate) or BB (she will never produce chocolate kittens). Note, we'll skip the fact that our female might carry cinnnamon (Bbl), this will complicate the case unneccesarily, we will come to cinnamon later on.

Case 1:
Your female carries chocolate - her genetic fingerprints are like that: Bb

 

  male
b b
female B Bb Bb
b bb bb
You see, you'll get 2 chocolate kittens out of this mating. But you can be also sure that all the black kittens carry chocolate.
Case 2:
Your female doesn't carry chocolate - her genetic finger prints are: BB
  male
b b
female B Bb Bb
B Bb Bb
You'll not get chocolate kittens in the first generation, but all the kittens are chocolate carriers. You must be a bit more patient. Mostly this is a good method, if someone starts to breed chocolate and doesn't want to buy so many cats, to cross the female with a chocolate male and produce kittens, which are all carrying chocolate and to keep one kitten. Next generation this kitten mated with a chocolate male or a chocolate carrying male will produce chocolate kittens, too.
 
[A] [B] [C] [cb & cs] [D] [Dm] [Fd] [I] [L] [Mc] [O] [S] [W] [XY]

 
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