New to Rat Breeding

[jasbus]

ON a good diet, with proper cleaning and ventilation, in small cement tubs, you should be able to keep a 1.3 in each tub with no rotation.
If you don't need huge numbers, do a 1.2 per tub.

with 3 females per tub, on average, you "should" see a litter every 10 days per tub. This is just an average, obviously, sometimes they will birth at the same time, or closer together. That's just a number I use for my records on my racks. Average litter obviously will vary, but you should be able to get litters of 8-12 on average. So, in a well established rack of 8 tubs with three females per tub, you're looking at 30-36(again, average) per tub per month. This is a low average, being that they gestate on average at 21-24 days...
I wean my rats between 3-4 weeks, and usually mom will burst again within 7-10 days. Sometimes, they will litter again before the last batch weans. This is how I do mine, and I retire females after about 6-8 months of production. There are plenty of other ways of doing it, better on the females to rest them, but for good output, this is what I do.
I also retire my females by rack, meaning, I'll retire a whole section, so I can keep up with how long they've been breeding. My racks are 7 high, two wide, usually I retire a whole row of 7. Of course, on occasion, I'll get a death here or there and have to replace one, but it's easier for me to do it this way. This also helps me keep track of a bad producer as well.
I also have a rack of retired moms, they live in groups of 5 or 6 for up to 2 months, just to be sure they're not preggo. I foster out pups to these girls to help ease any large litters or multiple litters in my breeding racks. Usually they will take pups for a month or so after they've stopped mating.