Well, since only few of us can afford to go on a photo safari to Africa or travel all the way to Australia in order to see koalas in the wild, for most the zoo is the only place to go and look at the kind of animals that don't have their natural habitats where you are. So the zoo IS the place for you to go and photograph animals other than what comes to your backyard or lives in the woods that surround you (provided you've GOT woods surrounding your place).
Which is why I personally think that taking photos of zoo animals is perfectly legitimate if you go visiting a zoo, and that it is a good experience to try and capture GOOD photos of zoo animals, too. Sometimes (or often?) zoo photography even forces you to become creative about the fences - all of that being steps for you to take.
So yes, on the rare occasions I go to a zoo, I'm bound to have my camera on me and take photos of captured animals.
Like you did here. Unfortunately, in many cases the light is not to your best advantage, such as in the case of the first photo showed here, where there was too little light for you to get a sharp, well-focussed photo. Which is a pity. But if this one's the only one you got of this particular wild cat (what is he exactly?), then ok.
Light apparently also was an issue in the case of the two of the little monkey, they're a bit soft.
After those, the other three look technically sound, in focus, and I like the koala and the parrots or loris - sorry, I can't tell those apart.