About the
Silver Inhibitor and Agouti Gene
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Genes
are responsible for the features of what your cat will inherit:
colour, coat texture, temperament. Eye colour etc. They come in
pairs and the letters representing them are as below.
Dominant Genes are: A
= Agouti, B = Black , C = Full colour, D = Density of Pigment, L
= Shorthair, O = Red, S = White Spotting Gene, W = full white
colour and I = Inhibitor
Recessive Genes are:
a = Non Agouti, b = brown, c = Himalayan pattern, d = Dilute, l
= Longhair, o = non red, s = no white spotting, and w = non
white.
Alleles
= are different mutations of the same gene
Homozygous
= the cat has the same two identical genes, BB = Seal/black
Heterozygous
= the cat has two dissimilar genes, Bb = Seal/black carrying
chocolate
Phenotype
= The external look of the cat.
Genotype
= The internal look of the cat, or what the cat may inherit and
carry on through the offspring. A seal silver tabby carrying
chocolate and blue = Aa Bb cc Dd ll II oo Ss
Dominant
= Show the effect of the phenotype in the cat, one dominant
gene must be present to see this, Bb = Black/Seal carrying
brown/chocolate
Recessive = When
the effect of the phenotype can not be seen in the cat. When
only one gene is present, this same gene must be there twice
to show the effect of the phenotype, bb = brown/chocolate.
The "I"
(Inhibitor)
and "A" (Agouti) are dominant in all
colours. The recessive genes can be carried through numerous
generations. Both "A" and
"I" are single and dominant. (what you see is what
you get) Keeping in mind that colour is
separate from pattern.
All cats have an agouti pattern
"A", visible or not. The "A" brings the
bands to the fore, and the yellow, fawn, brown under lying
colour. It is the most natural occuring gene going back to
nature.
The "A" Agouti gene
shows cats in patterns, as Tipped (Abyssinian), Classic
(blotched, bulls eye patterns), and Mackerel, (fine tiger
bands) and even spots. Introducing a solid colour to agouti
can create solids and agouti. Agouti to agouti can also
create solids and agouti.Introducing the Inhibitor gene
"I" with the "A" gene will turn the
yellow underlaying colour to white/silver, and the shafts of
the hair upwards white/silver, hence the banding comes to
the fore giving you the silver tabby. The "I" gene
with the cat that is not agouti "A" will be a
Smoke.The inhibitor gene,
"I", simply 'inhibits' the production of colour on
the hair shaft. As a result part of the lower end of the
shaft is devoid of colour and appears white or 'silver'. How you will see the silver is
determined by the polygenic activity. Polygenes control the
depth of tipping on the hair, varying from 1/4" to
1/2" down the hair shaft, the length of the hair and
density.Due to selective breeding the
polygenes can be governed and the results will be foreseen.
Polygenes therefore determine how dense the colour appears
to the human eye. The more silver, the less tipping of
colour present in the hair shaft, the lighter the remaining
colour will seem. Continually breeding
silvers to silvers and keeping the gene pool closed in, an
already small gene pool, can be considered undesirable and
would not help to improve the type. It is imperative to
introduce solids with silvers, to prevent inbreeding, and to
improve type.
Tarnishing is incomplete
clearing of the yellow pigment of the hair shaft. Resulting
in a dirty or tarnished silver which is a fault in a silver
cat. Shading can occur in all the colours of the Birmans for
many different reasons and is completetly different from
tarnishing.Some silver kittens born, with
more tipping (pigment) on the hair, can be mistaken for
solid colours, even though they are "low grade
silvers". Unless they are used for the silver breeding
programme, they should be sold as pets. As a result of
silver to silver matings and non silver to silver, in our
breeding programme, we have silver and non silver from both.
To be a breeder of silvers you
have to be clear in your decisions and have no doubts of
what the colours are, and registering them as such. To be
able to accept advice from other breeders that have/have had
silver breeding programmes, and to have a open mind. To
focus on the high grade silver, and the type as per the
standard, is a very exciting and different challenge. The dual registration for the
silver breeding programmes, ie: Blue Silver Tabby = 52 s/FA,
Blue Tabby pt = 52 FA(s) is recommended to prevent any
argument for breeders not wanting silver in their lines in
the future.
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Grand Champion Kyat Fancypaws Polar Bear
In
my opinion nothing could
be more beautiful
than a
Silver Birman that sparkles inside and out.
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Sandy Steward,
Noelene Dally, Pauline van der Hoorn.
Fancypawz
Birmans
Look at great websites with genetics
for cats...
this link.
Or this one......
Please respect the Copyright
Copyright Fancypawz
©
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