Somewhat New to Breeding

Question
I'm somewhat new to breeding mice, and I have a few questions about it. I've bred one litter before between an albino, red-eyed couple. Now I've got one of the does from that litter and a new male from outside of that gene line. He's also albino with red eyes, and they mated last night and today. My question is, I also have 2 younger black does in with the two that have mated, and I'm wondering if the male will mate with them as well? If he mates with them, will the pinkies be mostly multi-colored, or probably mostly albino? I've never bred a black doe and I really love the multi-colored ones I've seen online, so I'm hoping for some of those. Also, can the buck stay in the cage with them the whole course of pregnancy? I'm going to remove him when the pinkies arrive if he shows signs of aggression or cannibalism, anyway, I just don't know if he can stay with them the whole term of pregnancy.

Thanks :)

~Kait

Answer
Hi Kait,

This is a GREAT question!  The male will mate with any females he is housed with, so you should only put does in with him if you are intentionally breeding them to him.  We typically write genetics using a capital letter for dominant genes (ones that show through even when a mouse only receives it from one parent), and a lower case letter for recessive genes (ones that a mouse has to receive a copy of from BOTH parents in order to show that trait).  Albinism is caused by a pair of recessive genes:

C/C = full color (black, red, brown, anything that isn't white with red eyes)
C/c = a mouse with one full color and one albino gene will show normal colors, but has a 50% chance of passing on the albino gene to future offspring
c/c = albino (this mouse still HAS normal color genes, but can't show them because the albinism masks them)

So in this case, an albino mated to a black mouse would have offspring who ALL show colors (unless that black mouse is secretly carrying and hiding an albino gene).  One parent would pass on black coloration, but the albino parent could be hiding anything under that albinism, so what you would get would be a lottery.  Dad would pass on an albino gene (c), and mom would pass on a full color gene (C), so every single baby in the litter would be C/c (look all sorts of colors, but be carrying albinism that might pass on to future offspring).  If you breed THOSE offspring together you will start to see albino babies, because each sibling will have half a chance of passing on albino genes and half a chance of passing on normal ones.

This is important to understand if you plan to breed the offspring, because that albino gene will continue to be carried on and on through future generations.  Usually the only reason to breed an albino with a colored mouse is to introduce other characteristics and traits to an albino line (temperament, size, health, parenting, etc.).  That's not to say that you can't, but you should carefully plan each mating so that it benefits your chosen lines (otherwise it's easy to end up with 200 mice that you can't/don't want to breed!).  Hopefully I didn't make this too confusing, but this site does a really great job of explaining mouse genetics, and I used it a LOT when I was first learning it:  http://www.hiiret.fi/eng/breeding/genetics/index.html

As far as keeping the male with the female(s) during pregnancy, I try to do this as little as possible.  The male will keep trying to breed with her, which will put additional stress on her during her pregnancy.  Also, momma can and will get pregnant THE same day she gives birth, leading to back to back litters that is not only hard on her, but hard on her pups, and can lead to high risks of complications.  Some males are not very focused on breeding or harassing the moms, and some of them are great daddies, but in my opinion it isn't really worth taking the risks if you can avoid it.  For this reason, I usually time to have females with males for two weeks - this gives them 2-3 estruus cycles during which to conceive, gives me a good, 2-week period to look for litters, and gives her at least a week to get used to a cage swap before she has to worry about nesting and the stresses of mommyhood.

Hopefully I answered all of your questions, but if you have anything else to ask or need something explained, please feel free to write me a followup.  Welcome to the wonderful world of mouse breeding!  :)

-Tam