If been breeding them now since the beginning of the summer and it’s going very well now. It took about three months before it really started going well. Just like @saleengrinch I had the problem of them eating the babies. I discovered that when I give mealworms to the pregnant and nursing females this really stopped. When I put them with pregnant and nursing girls they immediately start eating them. If none is pregnant of nursing they hardly touch them. I feed mixed mouse food with different grains and dried veggies, pig food for nursing pigs, bread, veggies and the mealworms.
The second thing is not to clean the whole cage when there are babies. When I see the cage dirty I use a children’s beach shovel and remove as much as possible without touching the babies and then put new bedding in. I had it twice that a female started biting other females. Unfortunaly for her (both times the same female) she is now in the freezer and her daughters are now taking over as breeding females. Also the one that was always biting me is now in the freezer. Sad for her but a lot more relaxing for me. I can now put my hand in every enclosure without a problem.
I leave the babies quit long with the parents because I discovered they grow better if I separate them at the size of a normal adult mouse. I tried separating earlier before but they where growing a lot slower and became more shy and a little more defensive. Also several died. I did keep one male on three females but it got quit over-populated very quick and aggression got more. Now I keep 1 male on 2 females even though I use hamster cages of around 75 cm x 50 cm instead of the usual breeding tubs. The hamstertubs give some extra space for training wheels and extra hiding spaces for the ones that want some “privacy” 
I now every week cull about 12 of them…just empty one full enclosure of adults and after that I clean the whole cage and put the rats in that are ready to leave the parents. If I only need really big ones I leave a cage with only males grow up to really big ( males get bigger). I breed now in three cages and have 3 for the ones that left the parents. After they left the parents at the size of adult mouse it takes about 3 weeks to get to around 70 + gram for the males and around 50 gram for the females. Two ball pythons prefer rats but do eat ASF’s if they are hungry, One only eat ASF’s but the rest get one week ASF’s the other week rats so they don’t get to used to them. I only feed them dead because now I finally got all snakes on frozen I don’t want to go back to life again. In case I ever decide to stop breeding rodents at least I don’t have to switch again.
The one real problem I had recently is that in one cage they made a hole and five mice escaped. The other 20+ didn’t even though they had the chance. The funny thing was that two where so tame they walked right up to me. The second was not separating the males and females in time so a female got pregnant. The thirth was not noticing the female was pregnant until I already killed her. Now I separate males and females once I really want to get big, and doublecheck for nipples. If I see nipplies I leave them for two weeks to see if their belly grows.
For now I am happy with the breeding. I don’t want more because of the work and I really don’t like the killing, even though they die softly with co2.
Here some pictures
