Does anyone know of conservation programs that are using hybrids to increase gene flow?

Question

or alternatively some conservation programs where this has been seen to be detrimental to conservation of rare species.

Answer 1

The only one I can think of is Lipizan horses, they are a rare hybrid of many breeds.  About once every 40 years a purebred of one of the original species is introduced into the breeding program to maintain genetic variety.

But I can't call them a rare species.