Stab in the dark, not looking for super-precision here. Assuming well cared for stock, good breeding practices, etc. How many litters can be expected from a rat? 3-4? 10-12?

I'm just starting my rat colony...So I'm can't stay first hand...Wild Bill could answer this better then me :yessir:

Average for us is around 5 but some have done up to 10.:yessir:
Edit: We notice that the females start to look like crap after 5 or so...So we just feed them off and replace them.

Usually female rats are most productive from 3 months to 7 or 8 months of age for me. So I would say I get about 4 months of good production of good sized litters. This has a lot of factors for other people, this seems to be the most important.

Do you keep the males in with the females or have seperate birthing tubs?

If you keep them in with males I think it shortens their productive span because they get pregnant right away. Where if they are seperated they kind of get a break from being pregnant. Which I feel makes them last longer. I like having the birthing rack also, because I can see when a females litter size is getting smaller and make the decision to retire her. I try to constantly have females and a couple males being raised as replacements.

I use the 12 week rotation, rotating all the females through one male's tub. 1 month pregnant (well, 23 days), 1 month nursing, one month recovery. I have 2-3 females in a tub 27x19x6. I have a couple of backup males, but should probably save some more females.

How long a break after weaning do you let them have? 4-5 months production doesn't give many litters with 7 weeks devoted to gestation and nursing each round.