Meerkats under wraps

Meerkats in the wild would apparently breed like rabbits which is why any zoo in Australia only has single-sex populations just in case they stage a mass break-out. I had thought the person who told me this was pulling my leg but this is what the keeper explained during the talk at the meerkat enclosure at the Darling Downs Zoo when I was there the other week. So, where do the new/replacement meerkats come from? Are there special "breeding pairs" safely tucked (read: locked) away somewhere to boost the numbers when a replacement is needed (I was going to call it "natural attrition" but that would suggest they were leaving of their own volition - nope, we don't want that!)? Or do they come in from overseas? Or do they use AI for the job ... which would work in female populations, but not so much the male populations.