This article is from the WSSF 2016 AFRMA Rat & Mouse Tales news-magazine.

By Karen Robbins

Jody Oakes, Another Love Rattery (ALR), FL, e-mail
Q I have your Rat Genetics book. It tells me that if I breed a Rex with a smooth coat, I will get approximately half Rex and the rest smooth coat. In another small area, it says to keep a Rex male and a smooth coat sister and breed those two. What is the purpose of this? Will it give me more than half Rex in a litter? Or will it make the Rex coat better? I am just not understanding, and I am introducing Rex into my line and would love to know the low down on this to determine what I need to keep from my upcoming litter. Thanks!

A You won’t get more Rex by breeding brother/sister. We have found that certain colors have a better coat than others, e.g. Agoutis usually have better coats than Blacks. I’m not sure on the answer to your other question, but breeding in family lines is better than continually outcrossing each time unless you need to correct flaws (see the online articles for more on inbreeding, line breeding, and outcrossing www.afrma.org/breeding-inoutline.htm, www.afrma.org/brdstf_inbreeding.htm, www.afrma.org/c-c_win2000.htm, and http://web.archive.org/web/20080314202407/http://www.netherworld.com/~cowboy/SelectiveInbreedingMenu.html). Sorry I can’t be more definitive. Like Nick Mays says, outcross when type or other things begin to diminish.

Double Rexing only occurs when you breed two Rex together, so as long as you always breed Rex to smooth, you will be OK. Since Rex is dominant, you either have it (shows) or you won’t (a parent has to be Rex to get Rex kids), so it won’t carry and show up by breeding non-Rexes together. There are other curly coated genes in fanciers’ stock but you usually can’t tell by looking at them which ones they are. Also, more than one curly gene may be present on a rat. If you breed two curly coated rats together and don’t get double Rex (patchy/bare rats), or breed a curly rat to a smooth and don’t get curly kids, you may have one of the other curly genes. See the AFRMA Rat Genetics book (Other Interesting Coat/Color/Misc. Genes section in the back) for more info on each curly gene.

Lauren Holtzclaw, Legends Of Rock Rattery (LORR), GA, Facebook
Q Is there a name for a coat type in rats that is very, very short and really soft? When I rub it backwards it looks and feels like crushed velvet. I’ve had this line for 4 years and its been only standard coats. This same line did just surprise me with Siamese though.

Also, I definitely have some different coat types going on here, check out the whiskers on my new babies. Dad has a standard coat, mom has a very soft coat but looks standard. Their mother has a softer (feels like a feather) than normal coat that is a little longer than standard coats. These babies aren’t from the line with the short fur. I’ve never seen Satin before so I don’t exactly know what to look for. Is it too early to tell?

A Your description of the short-coated rat sounds similar to the Velvet rats that Karla Barber (San Diego) was working on, but hers weren’t very, very short as you describe. Also, the Velvets would take a few months to show their coat before you would know if you had one or not. The rat in your photo doesn’t look like it has a stand-up or thick coat like the Velvet rats have but rather looks like just a standard coat. How old is this rat? Do your short coated rats keep this short coat throughout life? The Velvet rat’s coat looks similar to a Rex rabbit—short, thick, plush, and stand-up, where this rat looks more like a Standard coat that is lying flat against the body. Are the guard hairs a lot longer or about the same length? I’ve seen Standard coated rats with longer-than-normal coats and very long guard hairs and it is a matter of breeding against long coats in your Standard animals. It looks like this is a Standard rat with possibly a shorter coat than is normally seen.

In mice, the English show mice have been selectively bred to have a very short, sleek, hug-the-body coat where the pet types have more of a longer, fluffy-type coat—it’s all in the breeding.

Here on the two monitors, the color of the short-coated rat looks brown, almost like Cocoa or a light Burmesey-type color—is it brown or gray in real life?

In the photo of the 3 babies, the little one in the middle looks like it has wavy whiskers which is typical of Satins though it doesn’t have the darker color from being a Satin. Do you have Satin in the lines anywhere that you know of? Satins don’t have very-short-crushed-velvet type coats though so you may have something new or they just have long whiskers. You can see photos of Satin whiskers (there is a photo of an adult female, along with the baby whisker pics) and various ages on these pages: Satin Rats article and Satin Rats - various ages and colors. At the age of your babies in the photo, you can easily tell which ones would be Satin. Once the babies start to get fur, you can tell the Satins in the litter by the darker color they have compared to Standard coated siblings of the same color. Your babies all look like Russian Blues with Standard coats, but very cute nonetheless.

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