This article is from the Fall 2003 AFRMA Rat & Mouse Tales news-magazine.
Colors & Coats
From Karen Robbins
Kim Richardson had gotten 2 young female Black Variegated rats from me that ended up pregnant (they had been with 2 males — a Black Self and a Black Variegated with a crooked blaze — at the same time). They each had a litter and there was such a wide array of markings it turns out BOTH males had sired babies in each litter [see the Medical section “2 Fathers Sire 1 Litter???” in the Fall 2002 issue, Ed.]. Elisabeth Brooks had gotten one of the babies and asked me, “It would still be possible, would it not, that either father could be Surprise’s (the Variegated female I got from Kim — from Yuma’s litter) sire since her mother was a Variegated, since Variegated is Berkshire with modifiers?” and Kim asked, “Is it your belief that all of the Selfs came from the Self father?”
Answer from Karen Robbins
The Self could be the father of some of the Berkshires. The Variegated guy could also be the father of a small percentage of the Berkshires as Berkshire is one of the markings (small percentage) you get when you breed two Variegateds. So, hopefully none of the Berkshires were sold/kept for breeding as you wouldn’t know who was dad unless you did some test breedings (or did DNA testing on them). The only ones that you could know for sure would be the Variegated kids.
There should be no Self kids no matter who sired the baby. If the baby is light colored like Beige, then it may be difficult to see the white markings on the chest/belly, but they should have some white on their chest/bellies somewhere (tiny white spot/EI/I/Berk type markings). Genetically, you can’t get Self out of two Variegateds.
I’ve asked our genetic expert Nichole to answer your question in the genetic sense as to why you can’t get Variegated out of a Self/Variegated cross. Hope this helps.
Answer from Nichole Royer
Well, I’ll start off by saying that the genetics of marked rats have always been a great debate. If you check 10 different sources, you come up with 10 different versions. Thus, instead of going deeply into the specific genetics of Variegated rats, I’ll just comment on the observations AFRMA breeders have made over a long history of breeding marked rats.
What we have seen is that a Self rat bred with a Marked rat will produce babies, most of whom have some white on them, but not as much as the marked parent. Thus, an English Irish, Irish, or Berkshire rat bred to a Self will produce everything from a Self all the way through messy English Irish/Irish type markings. Keep in mind that this is only true for a “true Self.” That would be a rat that does not have any white on it and does not have any genes for white markings. It is possible for a rat to be genetically marked but have so little white on it that it appears to be Self. Often, these rats will have a very few white hairs on their chest, and white feet. This is of course very difficult to see, particularly if the rat is a lighter color. These rats are in truth marked rats at the extreme end of having minimal white. When bred, such a rat may produce babies consistent with it being Marked, not with it being Self.
Self bred to any of the markings with significant white on the top side of the rat (Hooded, Bareback, Capped, and Variegated) will typically produce Irish and Berkshire type babies. We have never experienced a case of a true Self bred to one of these “high white” varieties producing “high white” babies in the litter. Thus, you cannot expect to see Hooded babies in a litter where one parent was Hooded and the other Self. It’s not the slightest bit uncommon for a good Hooded bred to a true Self to produce very minimal white and in fact, can and has produced showable English Irish.
When breeding two “high white” rats together, once again you get a range in the amount of white on the resulting babies. It is not unusual to breed two Hooded rats and produce a few babies with significant color all the way down the rat’s sides. Are these genetically Hooded rats with too much color, or genetically Berkshire rats with too much white? I won’t even suggest which is correct and just say it’s normal to produce such a variation in a breeding involving two “high white” parents.
Regarding this specific question. There is a Variegated mom and a litter sired by two different dads all of whom come out of a specific well-known background. The dads were a Self and a Variegated. Out of the litter there were a range of babies, from apparently Self through Variegated.
Experience, and more specifically the result of breedings involving these particular bloodlines, have shown that what is produced by a Self x Variegated combination is in the messy English Irish/Irish/Berkshire range.
The same experience with actual litters has shown that a breeding between two Variegated rats will once again produce a range. This time from Berkshire through Variegated, and even right up to lightly marked Variegated with too much white.
A general rule that usually works well for marked rats.
Keeping in mind that a particular marking can be represented in a whole range of actual combinations (from way too much color to way too much white) there is a general rule of thumb.
Two rats with like markings (i.e., they are at the same level) can produce the full range of markings in their own level, and one level above.
Rats at levels next to each other will produce the range of markings represented by those levels.
Rats at levels separated by one level will produce mostly the level between them, but may produce small numbers of their own marking.
Rats separated by two levels or more will produce the levels between them, but will not produce their own level.
The levels are as follows:
2. English Irish
6. Masked/odd head spots/BEW
And yes, there are exceptions to every rule. This one will work in most cases however.
Regarding the Litters:
Berkshire with a head spot came out of Variegated (our Selfs are true Selfs and don’t have the white modifiers needed to produce head spots). Berkshire with way too little white (what we would consider EI/I messes) would have a Self father. Halfway decent Berkshire with no head spot would be in question.
Thus, my guess on fathers would be:
Yucca’s Litter (10) (info sent when litter was 3 days old)
7 Berkshires (Black) – could be either male
1 mismarked Bareback – Variegated male
1 Blue Berkshire – Could be either male...depends on if both potentially carry blue? [My guess is the Variegated since there was Blue in the mother’s litter. Karen]
1 Blazed mismarked Variegated (KK Sir Prize owned by Kim Richardson) – Variegated male
Yuma’s Litter (12) (info sent when litter was 2 days old)
1 Blazed mismarked Berkshire – Variegated male
4 Black Berkshires – could be either male
1 nice Berkshire with head spot – Variegated male
2 Blue Selfs or Berks (probably Berkshire) – either male
1 Beige – depends on if both males might carry Beige [Again, my guess would be the Variegated since they had been throwing Beige as well as Blue. Karen]
2 mismarked Barebacks – Variegated male
1 sloppy Variegated (KK Imagine My Surprise owned by Elisabeth Brooks) – Variegated male