I have posted before (here and here) regarding conservation in tigers. This article from ScienceDaily.com talks about the potential genetic value of many captive tigers.
Conservation value is typically defined as the "closeness" an animal's background is to wild "founder" animals. There are many tigers in captivity, most of them probably in private hands. Surprisingly, in some areas it is cheaper to get a tiger cub than a purebred dog. If some of these animals (most of whom have an unknown genetic heritage) prove genetically valuable, that could greatly help the overall health of all tigers, and may bring some of the most threatened subspecies some much-needed genetic diversity.