American Fancy Rat & Mouse Association

This article is from the WSSF 2007 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Test Breeding Agouti Burmese; Reverse Siamese Mice

By Karen Robbins

Test Breeding Agouti Burmese

Ken & Connie Van Doren, Happy Go Lucky Rattery, Whittier, CA
QWe did a test breeding of our “Wheaten” Burmese female to a Cinnamon to find out if our “Wheaten” is Agouti Burmese or Cinnamon Burmese since she is so red in color.

It looks like we have two colors in the babies, not sure what they are yet (maybe Cinnamon and Agouti?).

The brown looking ones all have very light (almost pink bellies). The black looking ones have lighter black bellies.

What does Agouti Aa mean (in laymen’s terms)? Did we prove or disprove anything? Concerning mom: Could the red come from the Agouti background in the “Wheaten”?

Update: the outcome of the colors of the babies were 9 Agouti and 3 Black.

Agouti Burmese rat
The Agouti Burmese female in question, owned by the Van Doren’s. Photo by Karen Robbins.

ABy your photos it looks like you got Black (black bellies) and Agouti (pink bellies) which would mean your rat is Agouti Aa (Cinnamon dad would have to be Aa as well to get Black).

AA or Aa is both Agouti. AA just means it is not carrying “self” aa so if you breed two Agouti colors together and don’t get any self rats, then they are both either AA or one is AA and the other is Aa. The only way to get self by breeding two Agouti colors is they both have to be Aa, which is what happened with this breeding. Since there were no Cinnamons, means mom is not carrying the Mink gene mm so she has to be Agouti. All the kids now carry the Mink gene from dad so if you breed brother/sister, you will get some Mink in their litter. If you breed a son back to mom, you won’t get any since she doesn’t carry it. Also, the kids now carry Burmese from mom.

Outcome of LitterMom: Aa
Dad: AAAAa

Bonnie Walter’s genetics series in the AFRMA “Mouse Genetics” book explains “boxes” (Punnett Squares) and how when you breed two things together, what you end up getting. So in your case Aa to Aa = ¾ Agouti (¼ are pure, ½ are carrying self but they all look the same) and ¼ Black—this looks about the percentage you got with your 9 Agouti and 3 Black.

As far as your Agouti Burmese female being so red in color, it could be because the Siamese used in her background is out of dark Siamese selected for dark color-depth modifiers. It could also be from the many different colors she could carry since there is Russian Blue (dd), Lilac/Mink (mm) (though with this test breeding it was proven that she doesn’t carry this), and Fawn (rr) in her background.

Reverse Siamese Mice

Jackie Oppelt, New Jersey e-mail
QI’ve seen Reverse Siamese mice before, but I’ve never been able to find out just what they are genetically. Could you give me any info about them—which gene it is, or what to breed with them, or anything like that?

Reverse Siamese Mouse
A Reverse Siamese, owned and bred by Nancy Ferris. Photo by Craig Robbins.

AReverse Siamese (called Stone in England and not shown there, and I was told by one breeder the males are not kept) is genetically cece, the same as Beige but dark, and the dark version of Ivory cec (called B.E. Cream in England). You will get the Beige (light cece)/Reverse Siamese (dark cece) out of some of the Ivory litters. England recommends breeding in a Stone/Reverse Siamese once in a while to the Ivory. Since we made a separate standard for the Reverse Siamese, they can be shown. To keep the dark color, you breed them to each other and select for the lightest “points.” The darker color shows up the “reverse points” the best if you want to continue this as a separate color. You need to cross the Reverse Siamese (cece) with PEW (cc) to continue the Ivory cec). *

Updated January 21, 2015