American Fancy Rat & Mouse Association

This article is from the WSSF 2012 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Determining Father Of Litter: Self or Essex?

By Karen Robbins

Mayumi Anderson, Bii Rattery, CA, e-mail
QI had a female in heat and put her with a Russian Blue and Russian Blue Agouti Essex. The Russian Blue bred her once before I took her away and kept her overnight with the Essex. The Russian Blue must be the father of this litter because mom is a Self and I did not get any Essex babies out of her. I got three boys and one girl, all Russian Blue. I have never had just Self babies out of an Essex breeding except her. I thought differently when I did not find any Essex babies if dad is the Essex. I thought she had just four babies and that was why she did not get any Essex that time.

Have you ever had just Self babies when you breed Self and marked?

Don’t Know

ASince you only got four babies and Essex produces Self, there is the chance that you just didn’t get enough babies born to have Essex show up and only Self showed. But since you can have multiple fathers sire litters, there is the possibility that the Russian Blue is the father to one or all (did you see the Essex breed the female?). Because Essex breeds as if it is Self even though it has Berkshire markings (plus it is dominant), you won’t be able to determine who the father is exactly. You can try breeding her again but this time only have her with the Essex guy and see what/how many you get and compare colors/type to the litter you have now. Since the Essex is a Russian Blue Agouti, you should have gotten some Russian Blue Agouti. The small litter size and if he is not a dominant Agouti AA but rather Aa (carries self/non-agouti which means he would be able to produce Self Russian Blues as well), could be why none showed up even though at least half of the litter should have been Russian Blue Agouti this way. The only way to really know would be to do a breeding just to the Essex.

If you breed a Self to a true marked, it depends on what the marking is as to whether you would get any Self. The less white marking, the more chance of getting some solid babies. We have more on Marked rats in these articles:

Updated January 4, 2019