LOL.. our solution was to get more cows!
Seriously though, in regard to vaccinations, we use ours, then seal it well with masking tape, then store it in the fridge, for when we need it the following year. Yes, not ideal, but that's what we were told to do by other farmers. I don't know if its still working or not, but we've had no issues with what we vaccinate for, although there's never usually a lot left over, just enough to do a late lamb. We use the vaccine that does cows and sheep, so it gets quite a work out at our place.