Zoos are disturbing. The last time I went to a zoo, I watched a giraffe trying to reach a leafy tree branch that was outside its cage. The giraffe appeared to be pretending to chew on the leaves it couldn't reach. It made me sad somehow.
Next time you are at a zoo, especially after the animals have a bunch of babies, ask the keepers what happens to them when the grow up. If they tell you they go to other zoos, ask them what happens when there isn't any zoo to take them, what then.
Many go to exotic animal farms that hold animal hunts to make a living.