Rat Health Care & Information
The Burmese Variety
As the Burmese variety moves into guide standard it seems timely to give some history of this variety and also information on the genetics and general breeding theories we have so far. Hopefully the following article will give some enlightenment on this very attractive newer variety.
The Burmese variety was touched on by Claire Jordan in her articles 1998 and 2000 which although primarily aimed at the black eyed creams, mention other shades of ‘cream/taupe’ appearing in some of the litters. In conversation with Don Dickson recently, he confirmed that in hindsight, he is now convinced that the sister of The Milkman, Crystal, was not as first thought a cinnamon hooded, but almost certainly what was later defined as a ‘biscuit cream’ hooded. In those early articles, the ‘biscuit cream/taupe/stone cream’ was described to have “an unticked coat in a milky-tea taupe”. It appears we may have finally gone the whole circle with the Burmese variety and recreated the biscuit creams by taking the Himalayan gene back out of them and hence removing the points from the Burmese.
Sadly, records and memories seem to be fairly vague on some of the first few years breeding of these genes and also assumptions that the ‘cinnamony’ colour was cinnamon have since been proved wrong. By amazing luck it seems that two new genes (the black eye one and Burmese one) turned up at the same time when the two siblings were given to Don from the Edinburgh lab as it has since been proven that while both genes interact with the colour locus, they are not actually one and the same gene.
Claire Jordan and Brenda Dunn were the first breeders concentrating on the Burmese variety in the early years of their existence within the fancy. Neither breeds on a large scale and both worked primarily with Siamese and Himalayan rats for outcrossing to the biscuit cream and later the Burmese hence proving a relationship with the c locus and the feeling that Burmese must be on the c locus. The sable Burmese variety (2 copies of the Burmese gene) was also bred for the first time with Brenda Dunn in October 2001 – a rat called Scotratz Galaxy who many people saw at the Bradford Championships show in January 2002 when he was brought along to demonstrate the new variety. Burmese sibling Fudge and parents Biscuit and Toffee were also taken along and for many breeders in the south; this was the first time they had seen these two new varieties in the flesh.
Since 2002, a number of other breeders have taken on working with the Burmese varieties and many good examples are now seen at shows all over the UK and Burmese has done exceptionally well in the New Varieties class at shows within the last year or so.
Much like the breeding with the black eyed rats, as reported in the last Pro-Rat-A, many Burmese rat breeders have concentrated on ‘breeding more’, rather than testing the genes and the large majority of the matings observed with the Burmese do give the indication that the gene was likely to be on the colour locus. A small number of litters produced have skewed this idea and a number of breeders now believe that Burmese, like the black eyed gene, has a relationship with the colour locus in much the same way as pearl does with mink.
If we assumed that Burmese was on the c locus and in this example took Burmese as being cb, the specific varieties we see from test matings are: -
Sable = a/a cb/cb
Burmese = a/a cb/ch or cb/c
Wheaten (agouti) sable = A/- cb/cb
Wheaten (agouti) Burmese = A/- cb/ch or cb/c
Many breeders have added a number of different genes into the equation we are seeing various dilutions of the Burmese variety (mink Burmese, Russian blue Burmese and British blue Burmese to name but a few) and a number of shades of Burmese have been noted. Also breeders have added agouti into the equation, producing a very attractive sandy coloured agoutied rat with points. It had seemed fairly logical to assume that when Burmese wasn’t the shade it was expected to be or had lesser or greater points on the rat, that is was down to dilution and also down to the shade of Siamese/Himalayan rat used and in the early stages, cinnamon and mink was assumed to have been part of this equation as per the articles in 1998-2000.
When breeding for the Burmese variety, it has become very noticeable that if you use a show quality Siamese with really dark shading, the Burmese become almost sable in colour and way too dark for what we have been aiming for with showing them. On the other hand, if you use a very pale Himalayan or a pink eyed white to cross with Burmese, the Burmese can become too pale in shade and with less contrast between the body colour and the points.
Generally the many anomalies in shade of the Burmese had been put down to either the Siamese/Himalayan used or the fact that the rat was ‘probably’ something else as well, but some more recent matings are starting to show this as not necessarily being the case…
About eighteen months ago, I took a Burmese and paired him with his mink sister (their parents were Russian blue carrying Siamese x Burmese) and the resultant litter was sable, Burmese, Siamese, mink and black. The sable was later test mated with a Himalayan and all the resultant kittens were Burmese based (with some being Russian blue Burmese as both parents happened to carry that as well). The Burmese mated to a Siamese produced a normal litter of mixed Burmese and Siamese kittens. Now it doesn’t take too much genetic maths to work out that there isn’t room on the colour locus for more than 2 alleles to be displayed at once, so based on the above theory with the mink parent, we can only really have C/cb or C/ch and assume the Burmese parent to be cb/ch. This would have meant that the litter could not have both Siamese and sable in from these parents.
If we adopt another theory along the lines of where we went on the black eyed rats and we assume Burmese to have a relationship with the colour locus, rather than actually being on the colour locus, then all this becomes possible and it also answers many of the questions we have on the various different shades (and also points or not) on our Burmese.
Taking Burmese as being a separate and using for example Bu, we then get the following: -
Apply this to my mink x Burmese mating: -
This allows for the black and mink rats in that it’s possible to have a/a C/ch Mm = black and a/a C/ch m/m = mink. It also allows for a/a ch/ch Bu/Bu = sable and a/a ch/ch bu/bu = Siamese and of course a/a ch /ch Bu/bu = Burmese. (There was also a chance of getting Russian blue in the litter, but none of the kittens were, although several must have carried it.)
When this litter occurred, it was the first one known to not behave simply as though the Burmese gene was on the colour locus, and for quite a while, no-one seemed to have anything else that really seemed desperately odd so this litter was effectively ignored. In more recent months though, we have had the following litters which the theory of Burmese not being on the colour locus fits well with as there are too many varieties in the litter to fit with there only being 2 alleles allowed to be displayed at any one time:-
This also makes sense of several breeders who had bred PEW with Burmese and said it makes no real difference to the Burmese colouring and points…
Original theory = Burmese (cb/ch) x PEW (c/c) and therefore kittens being Himalayan (c/ch) or Burmese (c/cb) – the Burmese did have points although it was noted that the body colour was often slightly paled.
Alternative theory = Burmese (ch/ch Bu/bu) x PEW (c/c) – kittens = Himalayan (c/ch) or Burmese (c/ch Bu/bu), which then makes perfect sense of why they have points but are slightly paler. If you look at the 3 matings above when you effectively lose the Himalayan part from the equation, you also lose the points.
The theory of Burmese working in a similar way with the colour locus to the way pearl works with mink has been discussed amongst a few breeders who have sat down and worked through their own litters based on the ‘alternative theory’ and while many litters comfortably fit in with the ‘original theory’, all could easily fit in with this newer theory and it does quite clearly explain some of the anomalies along the line.
As Burmese is about to move to guide standard I will start with that variety.
The standard for the Burmese is as follows – “To be an even, rich mid-brown, devoid of dinginess, silvering, or patches, with darker points of the same shade. There is to be a strong contrast between the points and body colour. Eyes black.”
Burmese varies greatly on the shades that are presented on the show bench and the shade most breeders have been aiming for is actually easiest bred using mediocre Siamese or Siamese bred Himalayan with them. If a really good Himalayan is used, the Burmese tend to end up too pale and sandy coloured on the base colour with poor point contrast, while using a well shaded Siamese makes the Burmese almost ‘sable’ in colour. Unfortunately for the Siamese and Himalayan breeders out there, this means that Burmese breeders are not helping their varieties at all! Many breeders are guilty of exhibiting the too pale or too dark varieties and this doesn’t help our judges learn what they are supposed to be expecting from the variety.
Sable Burmese has two copies of the Burmese gene. As per Burmese, they vary immensely in shade and again the best are the ones with mediocre Siamese or Himalayan lines in the equation.
The standard for sable is as follows – “To be a warm dark otter brown with subtle darker points on the feet, tail, face, and ears. Devoid of dinginess, silvering, or patches. Contrast between points and body colour not to be overstated. Any suggestion of black in the points to be penalised. Eyes black.”
The biggest problem with showing both the Burmese and the sable Burmese is that both tend to be quite patchy and rusty in a similar way to many self varieties of rats and also there tends to be quite a lot of silvering in their coats as well. Both varieties do see random ‘marbled’ effect kittens in the litters and quite a number of them appear to have weird almost white patches appearing on their bodies. The marbling is clearly genetic and not moult related, although it does fade to a lot less as the rat matures. Selecting away from these marbled kittens for breeding seems to be reducing the occurrence of them generation by generation. The bucks are generally darker than does and do suffer the silvering most.
The agouti based version of Burmese is known as Wheaten Burmese.
The standard for Wheaten Burmese is as follows – “To be a mid sand colour, points to be distinctly darker than body colour. Base coat to be light brown. Belly colour to be pale silvery grey. Eyes black.”
This is a very attractive variety and like the self versions, does vary in shade dependant on the Siamese/Himalayan shades used in the lines. The too dark shades of wheaten Burmese can look almost like a bad cinnamon with points. Sadly the agouti based sable Burmese does look a lot like a bad cinnamon with points, so it is less likely a standard will be submitted for these for the time being.
As the time of writing the many Burmese dilutions being bred have not been submitted as new variety standards. The most striking of them I have seen is the Russian blue Burmese as many of the other dilutions of Burmese tend to look greyed or smoky and lose the definition between the points and the body and therefore maybe not striking enough to be worthy of their own class.
Like some of the black eyed lines, some Burmese have gained a bit of a bad reputation on temperament along the way so it is really important to select breeding rats with the best personality and temperament. Most of the temperament problems noted to date can be put down to hormones and in the case of bucks, castration usually solves the problem. In the case of the few problem does, they tend to be quite hard to introduce new rats to their cages. Like with any newer variety, it takes time to iron out everything and improve every aspect of the rats and there has been noticeable improvement in more recent generations. The type has also improved in recent years down to better outcrossing to typier rats rather than just breeding to ‘make more’.
The Burmese has become quite a popular variety and aside from the UK, they have been exported to the USA, Netherlands, Belgium and Sweden and are proving to be equally as popular in these countries as well. Data from outcrossing to completely unrelated lines to anything in the UK has helped to reinforce the genetic theories on the Burmese.
More Burmese pictures here.
Article originally published in Pro-Rat-A written by Estelle in 2005
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Last modified: February 08, 2017