Animals are not happy. If every animal in the Zoo is avoided carefully and appropriately. It's not wrong, ethics, and if that animal was put in place to maintain and preserve it not torture animals.
Animals are not happy If all of the animals in the zoo are fed well and proper. It's not unethical if it was put to the preservation and conservation was not considered as animal cruelty.
The animals are not happy. If all the animals in the zoo are Liang well and appropriately. It is not ethical and if the animals were locked to maintain and preserve it is considered not torture animals.