Silver Seminar
 
With permission: Copyright to the Birman Cat club of NZ.
transcribed from the Silver Seminar held By Avon Aspden
(Convenor of the NZ Cat Fancy Genetics Advisory committee)
for the Birman Cat Club of NZ on the 16.9.01.

 

Do not copy this text without personal permission
 from Avon Aspden and the NZ Cat Fancy
 
To breed really good silvers you need to do silver to silver matings.
 
The main thing to remember in cats is that there are two types of pigment, eumelanin, which is black and phaeomelanin, which is red or yellow. The black pigment is modified to produce the many different colours such as black, chocolate, blue, etc, and the red also comes in the dilute version of cream.
 
All cats are tabbies, they are bred selectively so it is not visible. You do need to understand the tabby mechanism to enable you to understand how silver works. In an ordinary non silver tabby both types of pigment occur you have the hair growing up, starting with the dark eumelanin at the top. It is controlled by an agouti protein which as it builds up,  cuts down a product called tyrosinase (an enzyme occurring in many organisms that is a catalyst in the conversion of tyrosine to the pigment melanin; inactivity of this enzyme results in albinism). As this particular chemical is reduced the colour in the top of the hair is cut off. Once the black eumelanin is cut off, the red or yellow starts to flood in. Depending on the type of tabby ( ticked, classic, mackerel or spotted), you have,  will dictate the number of black, chocolate or blue bands with the yellow pigment floating in. When you have silver the silver inhibits the yellow pigment from coming through, but it only works on the lesser levels of pigment. So you have the wonderful dark pigment of colour at the top and the silver clears out the yellow band. If you have an Abbyssinian for example, you have more dark pigment on the ends of the coat, with the yellow cleared out underneath to give silver.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

In a red cat where the colour is really strong at the top, it stays strong at the top but the second flush as it does a pulsing action cuts out the next bands. Silver is just a lack of colour, which cuts out the colour and stops the yellow flooding in. It is purely a lack of yellow pigment in the spaces where the dark pigment has come down, shut off, floods in (and you get a bit more pigment), and cuts off again, the areas where it shuts off are made clear.
 
Because you get different types of tabbies, you will of course get varying degrees of silver. The more coloured barring and therefore pigment a tabby has the lesser degree of silver there will be. A chinchilla is still a tabby, it is produced by a wide band gene reducing the colour, you get a tiny bit of colour at the tip and a big clearing out of colour underneath, producing a wondrous silver look. Of course it is not really silver it is just that there is no pigment there.
 
Then you go to the shaded’s. People believe shaded’s are bad tabbies, they are not, all they have is just a bit more pigment than the chinchilla. So you have a little less of the clear area underneath.
 
Now the silver tabbies, which obviously come in all sorts of colours, have tabby stripes from the tip of the hair, almost to the bottom. The in between hairs might just be tipped, so that the clear bit is not totally clear in the shorter hairs underneath and you are still getting that look of the dark marking with the silver that has been cleaned out in between the markings.
 
Silver is not to be confused with the brindling as seen in the pointed cat. In a pointed cat, stress or illness can lead to brindling and coat colour changes which can be confused on the show bench as silver, by an in experienced judge, when in fact there is no possibility that it can be a silver.
 
High and low grade silver refers to the amount of hair that is silver or not silver, high grade is obviously more silver and low grade is only a tiny bit.
 
I can tell you a classic story. I have this little low grade Seal Smoke point Siamese (Sayonara Myrrh-Maid (pedigree below) that was throwing the highest-grade silver I have ever owned in my life. A friend asked me to put her in a show to make up the Siamese numbers, so I put her in. Well I had three senior judges who told me they would have thought I had more experience and know how than to call her a silver. When I said that I get high grade silvers from her they said well you must be mating her to silver (which was not the case) They just did not understand how silver works. A lot of very low-grade silvers seem to throw the most exciting high-grade silvers you will ever see.
 
Silver is a dominant gene and cannot be carried. There is perhaps confusion of the term carrying silver due to the fact that people think their cat is carrying silver because they cannot see it, where it may in fact be a very low grade silver. Frequently low-grade silvers need to be bred from to positively identify them by their progeny.
 
Cats get more silver as they mature i.e. some babies are quite non-descript with their colours, but the silver develops as they get older. When silvers are born till they are almost a month old the silvers have the very, very tips of their toes and the tips of their tails lacking in pigment and are pink (as in totally devoid of any colour).The tips of the toes, tail and even around the mouth are pink...like new-born mouse pink. Almost transparent, in fact that is the best word to use. You know Siamese and Birmans are born white but the white does not extend to the end of the tail and toes. My own personal belief is that because you have an inhibitor gene it inhibits ANY colour going to the very extremities. Once kittens get to a month old it will be lost, but if you mark those kittens they generally turn out to be your silvers. It is so noticeable. I went away for two days and left a litter of two and half week old kittens with a friend. When I came back she said “I don’t want to upset you but you have a white spotting gene in your Siamese kittens”, those were in actual fact and turned out to be my Silvers!
 
Chinchillas are born tabby but because of the mechanism of the wide band gene the pattern is lost as they get older, but they often retain the typical tabby M on the forehead.
Dual registration as per the NZ Cat fancy regulations is recommended because of the low-grade silvers, which are difficult to identify. I had a classic example of this. I bought a seal tabby point in from Australia many years ago. I kept two daughters for breeding, fortunately, as one developed pyometera and had to be spayed. One of these daughters mated to my Havana turned out the most wonderous high-grade silver tabby. This was going back to 72’ 73’ I bought this cat in. In the last few months I joined the shorthair linechasers group on the Internet. And discovered that about 8 generations back from my import was a silver tabby domestic! Australia registrations are notorious for not showing silver, so we have come all this way without dual registration and I have this beautiful little girl that to all intents and purposes looks like a seal tabby Pt, but is in fact a low grade silver.
 
Breeders should have the choice to use silver lines if they choose if it is recorded and visible on the pedigree as indicated.
 Seal Silver tabby 52s/F or Seal tabby from silver lines 52(s)/F
 
NZCF Regulation
6.7 Smoke, shaded or silver Tabby
 
Any progeny bred from smoke, shaded or silver tabby parent/s, but with the phenotype of non-silver (ie phenotype of Solid, Broken Pointed or Tabby) shall have the registration Certificate endorsed with the genotype of the smoke. Shaded or Silver tabby variety. This shall apply for all longhair and shorthair Breed/Type Division registrations. Should any of these cats with dual registration  (eg Breed1[6]) at a later date change coat and become clearly identifiable as Smokes, Shadeds, or silver tabbies, application may be made to the appropriate Registrar to delete the non silver part of the breed number (ie delete 1 and leave 6).
 
Note: The inhibitor gene, being dominant, may be passed on only by a parent who is itself Smoke, Shaded, or Silver Tabby (ie the Gene cannot be carried invisibly). As the inhibitor gene, however is extremely variable (being polygenetic in origin and not easily manipulated by selective breeding) some progeny may have such low grade expression of the Silver factor that they are indiscernible from non-Silvers. Nevertheless, upon maturing, such kittens may reveal themselves to have been low-grade smokes, Shadeds or Silver Tabbies all along. Although actually smokes/Silvers, they may nevertheless remain indistinguishable form non-Silvers with only their silver progeny revealing their true genotype.
 
In these circumstances, dual registration will enable these cats to be exhibited according to their phenotype and also enable their Smoke/Silver progeny to be registered. The dual registration shall apply for succeeding generations.
 
One of the tricky things with silver is that you don’t always completely clear out the yellow pigment, this is called tarnishing. Tarnishing is usually evident across the nose area on the front of the feet and across the shoulders. If you have young kittens and they have it on the shoulders that generally grows out with the new coat that comes through, but by the time you sell them if they are still tarnished on the feet and nose it generally stays and is a fault. This can come about if you are not always doing silver to silver matings. You are not really getting a clear cut squeezing pattern, cutting off the pigment squeezing it out and clarifying it properly. This is something not often seem in Chinchillas due to the fact that they are usually from many generations of chinchilla to chinchilla matings and they have the polygenes for these features down pat.
 
Silver tends to create a somewhat washed out version of the original colour in the smoke. If you put a seal smoke next to a seal point the smoke tends to look slightly washed out in comparison, depending on the degree of silver present, it may only be that the seal colouring is slightly paler and no silver undercoat is visible.
 
Silvers generally have a colder appearance to their coats that tend to stay clear with age rather than turn yellow as do a lot of non silvers. Identifying silvers can be difficult but sometimes looking at the hair around the throat area, at the base of the ears, under the armpits and the base of the tail, is where you might detect some evidence of silver, but this is not a hard and fast rule, as discussed earlier when speaking of low grades.
 
Solid coloured cats frequently exhibit "spectacles" as well, and in many the colour inside the ears is much lighter.
With permission: Copyright to the Birman Cat club of NZ.
transcribed from the Silver Seminar held By Avon Aspden
(Convenor of the NZ Cat Fancy Genetics Advisory committee)
for the Birman Cat Club of NZ on the 16.9.01.
Do not copy this text without personal permission
from Avon Aspden and NZ Cat Fancy
 
 
Fancypawz Birmans
Cats of the future