Bei Black / Black is probably one of the first color mutations of the brown rat. Already 1901 black color rats were issued in Aylesbury Town Show and even the winner rat was an evenly-drawn black and white rat, Miss Mary Douglas was one.
The standard for Black
In the standard the National Fancy Rat Society a dark dense black is required without white hair or patches. The undercoat and the feet should also be black, just as the eyes. The standard of the American Fancy Rat and Mouse Association Black describes similar. Important is, that a very good Black Rat Self (d.h. a rat without insignia) is completely black, d.h. the feet and toes must be black, what is breeding very difficult to achieve. In addition, the rat must not Silvering (single white hairs) or rust (brown patches in the coat) respectively.
The genetics of the rat in black / Black
The allele for black is on the A-locus, on which also the agouti allele is (therefore "A" for agouti). Besides, black is recessive to agouti, d.h. a black animal is always homozygous for the allele Black (aa). the designation "Allele for black" is incorrect basically, as it correctly is a non-agouti allele. In homozygous aa animals is not the characteristic banding of Agouti trains, but the hairs are monochrome from the shaft to the tip. the designation "Black allele" is remotely misleading in so, as that Homozygous aa in all colors leads to a resolution of the banding. However, it is so, that in an animal, at which no further color is present homozygous recessive, just pure black arises.
In addition, a black rat should not Silvering (and) respectively, So, at best, have the genotype Si Si.
Tips for breeding black (black) rats
I once wrote to a potential customer, the "something special" examined in terms of coat color. then demand she gave a, in no case "easy, boring black rat" to want, since the so everyone would. With this assessment, however, the lady was quite wrong. Because the breed really good black elf (thus completely black rats without badge) is extremely difficult. On the one hand, the effect of so-called silvering must be minimized, which ensures, that the rats with age show white Stichelhaare. As this is visible only late, it is extremely difficult, to consider the factor in an early selection of future breeding animals. It's the same with the so-called rust, which ensures, that black rats get brown spots or. to brown verfärbe. It is especially difficult, to raise animals, which are really colored black to tiptoe. Here is a conscientious selection is necessary. It has shown, that the best black animals from pure black lines come, because mating with drawn animals always leads to white feet.
Illustration: Significant silvering on a Black Irish rat
Illustration: White paws on an otherwise black rat
Illustration: Black / Black can be seen clearly at a very early age, here at a 7 Day-old puppies
Illustration: Compare Black (links) and Chocolate (right)
Illustration: Black aged 10 meet