Charlie, for some of us with smaller breeding colonies or just an interest in rats for both production of feeders and enjoyment of managing a colony, it's a bit of a balance. You cannot realistically keep a lot of non-producers because that becomes a burden on your time and negates some of the financial benefits of raising your own feeders. However for me, a few older retirees or the occasional "I just like this rat so I'm not feeding it off" works. I tend to find them "jobs" (rats are social anyways so they need something to do). Some of my older rats keep control in the recently weaned feeder bins as I find an older, hand tamed rat to be a good thing in there - keeps the feeders calm and calm rats eat and grow better as well as being I believe safer live feeders. Some of my non-breeders are simply companions for the breeders as they cycle in and out of the breeder/maternity enclosures.