Ok nt sure how to ask this without possible offending someone so I bluntly ask this.

What the life span of a rodent if mainly used for breeding/(producing feeders) and how often to replace them with younger rodents.( this would be for like asf, mice or rats.

I kow I replace my asf when the tumorous lumps start to appear on my females no matter how young/old they are they go into the feed off bin and are only kept alive till such time that I got a snake ready to be fed to.
I don't breed mice to much.
I know wit hthe rats I usually have at least 3 tanks going at anyone time with something like 1 male to 3-6 females.( most the time these be the nice pattern ones I though would make interesting babies)
but I was wonderign how often I should consider replacing them? I try to keep one of the tanks with either a young colony ( just starting to have pups and such ) but I don't want to breed them unti lthey drop over dead. I aslo would need a way to reduce the larger rats after they retired/frozen off as i lack a larger snake to feed them too. ( only draw back to adult rats no larger python or boa as my clean up snake.