http://en.wikipedia.org/wiki/Raw_feeding explores the debate.

I tried raw liver on my cats. They did not recognize it as edible.
Freeze-dried liver snacks were gobbled up as fast as dispensed.

How does one introduce cats/dogs to raw food?

Oh, maybe the storebought liver was not fresh enough?
I'd occasionally find evidence that my housecats were
finding fresh prey - leaving me a mouse nose and tail,
apparently the only parts they found indigestible. Urk!