Colour and Coat Varieties
|
GreyThere are several 'flavours' of Grey Syrian Hamster, and this has led to some confusion over the naming of colours that use a grey gene as a component.
Dark Grey was reported in 1967 from a laboratory in Cambridge, Massachusetts. Interestingly, it came from a rust sub-line, inbred for 14 generations. Further breeding tests confirmed recessive inheritance, and the symbol dg (dark grey) was assigned to it. Dark greys were thought to be of reduced viability, as there was a shortfall in the expected numbers for a simple recessive gene. The authors documented a 10 to 20 gram reduction in body weight at 4 weeks compared to normal littermates, although mature weights were similar. Over the years, a number of other problems have beset the dark grey. Blindness is reported to be more common, but this is not a great handicap to an animal which normally has poor vision. Of greater concern to breeders has been the tail deformity which can vary from a subtle, scarcely noticeable curve to a tail which doubles-up upon itself, lying flat against the hindquarters. Sadly, no serious effort has been made to eliminate this deformity. At one time, some commercial breeders even selected for it, marketing the progeny as "Curly-tailed Greys". There is a general impression among breeders (which I share) that dark greys are less vigorous and less fertile than normal. This may have been the result of intensive inbreeding to produce litters of 100% grey animals. Dark Grey seems to be in decline in the UK at the present time.
The origin of the Lethal Grey is unknown. It was described in the same paper as the Dark Grey, but the authors freely admitted that they did not know where it had come from. Test matings determined that the homozygous (LgLg) animal probably dies in-utero, or soon after birth. To quote the late Roy Robinson, "The death of homozygotes should not be thought of as a detriment, for the Light Grey heterozygotes are as healthy as the next hamster, and an attractive colour". The heterozygote Lglg is a lighter grey with a more tan or yellowish tint compared to the Dark Grey. Examination of plucked hair swatches of both types of grey reveals a reduction in the orange-yellow pigment in the agouti band, and also lightening of the lower dark band in Lethal Grey.
Very much the latest addition to the Grey range, the Silver Grey has become established as a popular colour since its introduction to the UK in the early 1990's. The reasons for its popularity include a general vigour, docile nature and dominant inheritance, making it easy to breed. It is a lighter, cleaner grey than its older counterparts, with a corresponding reduction in the amount of yellow pigment in the coat. There is some evidence that the Silver Grey gene, designated Sg, also reduces the intensity of black pigment. It is not completely dominant, and heterozygotes show a variable amount of yellow in the pelage. The name Sepia Grey has been given to this variety.
Rust and Dark Grey together produce the Beige standard variety. The ideal is a soft pale grey with the Rust gene lending a brownish tone.
Another standard variety is the combination of Dark Grey and Cinnamon. It has less brown tone, tending to a paler lilac grey.
Dark Grey and Yellow together produce a very attractive pale grey-cream hamster which retains (ideally) the heavy black ticking of the Yellow.
The differing qualities of Dark and Light Grey genes are exemplified by combination with Cinnamon. Light Grey and Cinnamon produce a very pale creamy colour, with a richer yellow tone than the Lilac.
There is a bit of debate going on at present concerning which genotype is most appropriately referred to by the Ivory standard. Cream and either Dark or Light Grey is a diluted Cream, but the exact tone varies according whether Dark or Light Grey is the diluter.
When Silver Grey and Cream are combined, the result is that virtually all black and yellow pigment are removed from the coat, leaving a pure white hamster with dark eyes and ears. This variety was difficult to create previously, and there was debate as to its suitability as a standard, but it has now been granted full standard status.
Cinnamon, Rust and Yellow may each be combined with Silver Grey (SgSgpp, SgSgbb, SgSgTo/) to give similar colours to the above, but with paler, pastel shades.
The unfortunately-named Dingy Black shouldn't really be bred at all, as there is a risk that the dominant Silver Grey gene will get into stocks of black, and as the name suggests, its effect is not to be desired. It is of interest from a purely theoretical point of view, that the Silver Grey gene causes some dilution of black pigment. This is not, however, a new colour, and attempts to label it as "Blue" are not to be condoned.
I'm a bit of a fan of this colour. It is the heterozygous form of Silver Grey, and retains a variable amount of yellow pigment in the coat. It will not breed true, and mating one Sepia Grey to another will produce a proportion of Silver Grey, Sepia Grey and Goldens in a 1:2:1 ratio (on average). |
|
Beige (dgdgbb)