Fawn
According to the NMC standard, a fawn’s “colour can best be described as the deepest tan as on a black tan”. This is a rich orangey colour, which is best seen in the flesh.
A fawn is a pink eyed red, genetically “lethal yellow”, and is one of the few genes (A^y) that are dominant to agouti. Like rumpwhite, this gene is homozygous lethal, meaning that babies inheriting two copies of the gene (one from each parent) die at a very early stage of development and are reabsorbed by the doe. In the case of the A^y gene responsible for red and fawn, this is early in the sixth day of gestation. This is not harmful for the doe and it is ok to breed two fawns together, which will result in smaller than average litters.
Lethal yellow mice are also associated with obesity. Some breeders have been successful in significantly reducing the incidence of obesity in their lines, so it seems that this is not inherent in all mice with the A^y gene. To avoid young mice becoming fat and the risk that they therefore might not be able to reproduce, they are often bred at a slightly younger age than most mice (perhaps from 10 weeks rather than 12). Some people also advocate letting fawns have back to back litters to prevent a reduction in fertility. I cannot say if this is successful as I have never bred the variety myself.
A fawn is a pink eyed red, genetically “lethal yellow”, and is one of the few genes (A^y) that are dominant to agouti. Like rumpwhite, this gene is homozygous lethal, meaning that babies inheriting two copies of the gene (one from each parent) die at a very early stage of development and are reabsorbed by the doe. In the case of the A^y gene responsible for red and fawn, this is early in the sixth day of gestation. This is not harmful for the doe and it is ok to breed two fawns together, which will result in smaller than average litters.
Lethal yellow mice are also associated with obesity. Some breeders have been successful in significantly reducing the incidence of obesity in their lines, so it seems that this is not inherent in all mice with the A^y gene. To avoid young mice becoming fat and the risk that they therefore might not be able to reproduce, they are often bred at a slightly younger age than most mice (perhaps from 10 weeks rather than 12). Some people also advocate letting fawns have back to back litters to prevent a reduction in fertility. I cannot say if this is successful as I have never bred the variety myself.
Best Satin fawn satin bred by Sarah Cudbill
The type of fawns is not usually comparable to the big pale selfs – for example, they tend to have smaller ears. If an outcross to improve belly colour is needed, champagne tans are often used. This also has the added bonus of bringing in better type, size and ears than are generally found in fawns. In the nest, fanciers should look for the brightest orange coloured babies as these usually make up into the best adults for show purposes.