Last time I pernah dengar this story. But seriously like H say this is only a joke by some sick people. Cat is higer life animal, its not like some frogs or tikus or some small fish to feed bigger fish.
Anyway my dad use to supply some thing to IMR long before, at IMR they do feed the ular with tikus hidup. But these cannot be compard to higher life like feeding cats or puppy to lion. I think zoo is ethical ebough in their care.
However it is the chemical companies that does animal testing. Name any company (just any one except body shop) they will have some very unpleasant testign on animals.