http://forums.kingsnake.com/view.php?id=1447856,1450228

It's not really a debate, but on KS, it is argued that if the rats have enough food, they can easily get 5 litters out before they are made into feeders themselves on continuous harem breeding.

I know that all I can really expect out of cycle breeding is a good 5-6 litters before they are retired or fed off.

I don't know how old they are after 5 continuous litters, and I have no proof if it is detrimental to their health. All I know is that wild rats average about a year, and they will produce in high amounts until there are too many. I don't know how many litters they get out, but I'm pretty sure it's not 5 litters a year.

Just looking for some evidence for both sides of the story I guess.
(I personally cycle, and like to have my rats around for as long as they naturally can)