Actually I got the impression that they breed when the inv is closed, and if you open it the timer restarts. So I left them in the bank so they can breed peacefully. Maybe the check is made when you open the container, and it calculates how much time it was closed and does everything then.
Being seriously OCD about "crafting", I've started collecting the results of my breeding experiments in a Google Doc for easy reference and sharing. It's still missing several tribble types and lots of food types. I'm going to check other threads for any more info people have posted, then get back to the farm.
Donations of foodstuffs for experimentation, particularly the dropped ones, are very welcome. Feel free to request spare tribbles of a particular type, but please bear in mind that breeding in a controlled fashion is quite slow, so it may take a while before I can provide one.