Basic Genetics: Coat colour Silver, Smoke, Shaded, Shell, Silver Tabby

Gene I, i

INHIBITOR gene I

Gene I is responsible that the base of the hairs gets silver white.
It is dominant over its companion i. Therfore gene I must be present only once to see its expression that a coat gets a silver white underground.

Note that there is a clear difference between tipping and ticking.
Tipping is, when only the tip of the hair is coloured. Smoke, Shaded and Shell cats have tipped hairs.
Ticking is when the hair shows several bands of colour. Ticked cats are the Abyssinians and Somalis. Ticked tabby is a special tabby pattern, which we will discuss later.

Non-Silver gene i

Gene i is recessive to gene I. Your cat must have ii that its coat doesn't show a silver white underground.

Possible gene combinations

II homozygous
When such cats are used for breeding all their offsprings will be Silver.
Ii heterozygous
These cats will produce solid coloured and silver offsprings.
ii homozygous for being without white underground
All solid coloured cats have this gene combination.

 

What is the difference between a Smoke, Shaded and Shell and Cameo ?

 

silver tipped/ticked hairs In most hypothesis the Smoke (3) is said to be without agouti. Some theories say that there is a different gene for the smoke cats. Think about the smoke spotted Egyptian Mau, where spotting can be seen on a smoke ground, that would mean that these Maus must carry agouti to show the spots.
On smoke cats the silver white band at the hair base can be only seen when you part the hairs. From outside a smoke cat looks like a solid cat, only when the cat is moving the silver white underground gets visible. You can also see that it is a smoke cat when you look at the eye brows which are silvery, the cat is to be said to have frown markings, also the frill at longhair cats is silvery. To check wether the cat is really a smoke or a solid part the hairs on the front and on the legs, there must be seen a clear contrast. Sometimes blue cats or cream cats have a lighter undercoat and can be easily mistaken as smoke cats.
Shaded and Shell cats are agouti cats. You can see this when they are born, they look like silver tabbies. Shaded and Shell cats are the result of carefully selective breeding programs to diminish the tabby pattern.
Shaded (2) cats look darker in their appearance, one third of the hair tips is coloured, the rest of the hair is white. Mostly known are the black silver shaded cats, but the tipping can be of different colours.
Shell (1) cats almost look white, only with very little tipping, one eighth of the entire hair length is coloured. These cats are known as Chinchillas.
Genetically Silver Tabbies (4), Shaded and Chinchillas are the same.

While Smoke have deep copper eyes the Shaded and Shell usually have green eyes - except all the cats with red which have orange eyes. In some federations also shaded and shell cats with orange eyes are recognized, they are called Pewter.
Silver shaded/shell cats with red are sometimes called Cameos, f.e. red shaded cameo or tortie shell cameo.

Therefore on Silvers we can have the following gene combinations:

Smoke aa I- - For "I-" you can either have II (homozygous for Silver) or Ii (heterozygous for Silver)
Silver Shaded A- I-
plus genes for tabby For "A-" you can either have AA or Aa.
For "I-" you can have II or Ii.
Note that Silver Tabby, Shaded and Shell have the same genetic code for their coat colour.
Silver Shell A- I-
Silver Tabby A- I- Ta-

ticked
For "Ta-" you can have TaTa, TaT or Tatb.
If you put TaTa You'll find this f.e. on the Somalis or Abyssinians.
A- I- T-

mackerel
For "T-" you can have TT or Ttb.
A- I- tbtb

blotched
-
There are different theories how the silver white band at the hair base gets broader. We will discuss the Wide band gene Wd later.
We will also discuss the Goldens in a later lesson. You probably know that sometimes there were born Goldens from two Silver Shaded/Shell parents.
You missed the silver tabby spotted pattern ? We will deal with Spotted in our lesson when it comes to the various tabby patterns.

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

You want to breed Chinchillas.

If you really want to go for Chinchillas you should not mix them up with Silver Shaded. Why not ? Both are silver. But you'll have to cope with the following problems:

If you look in the pedigrees of some cats you'll find them all, Silver Shaded as well as Silver Shell, and even Smoke. It would be better to stick either to Smoke, breed Smoke to Smoke or Smoke to Solid, breed Chinchillas only to Chinchillas and Silver Shaded only to Silver Shaded.
If you really want to breed outstanding Chinchillas you should not mix them up with Silver Tabbies.
Chinchillas are the product of a very carefullly selective breeding program to diminish all the tabby pattern on them, to get rid of the rings on their front legs, to get rid of uneven tipping and to have them as light as possible, so that they almost look white with a sparkling silver shine. If you mix them with Silver Tabbies the stripes and ghostmarkings will be back soon.

You want to breed Cameos.

This is quite a difficult task, because Cameos should not show any stripes or ghostmarkings. You should not mix them up with Silver Tabbies, because you'll have to face the following problems:

You should also not mix Red with Cream, because otherwise you'll get those problems:

You see, breeding Cameos means carefully selective breeding and not to mix them neither with Silver Tabbies nor Red with Cream.


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Last modified on  99-01-16

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