Is it right to kill our animals?

I’m an animal behaviour and welfare student and got into a bit of a debate with someone on my course about Marius the giraffe, sparked by this article..

She believes a genetically “dead” animal should be killed in the name of conservation. That genetically sound animals should be favoured. That we dissect and kill animals every day without thought, but because its a “cute, cuddy mammal” opinions are different. 

I do not agree. Call me a hippy or whatever, but an innocent, healthy animal does not deserve to be slaughtered. It is the humans fault alone that the animals have become inbred. We have kept them in captivity. It is especially unjust when it is an animal such as the giraffe. It’s status is of least concern, it is merely there for humans to look at, there is no conservation purpose. The zoo had plenty of offers from other places who would have taken the giraffe rather than kill it. They didn’t give the giraffe up to any zoos, including one in Yorkshire with giraffe facilities and a space for another male because “any space should be reserved for a genetically more important giraffe.” Personally, I don’t agree with this, humans putting animals into captivity and killing them because they are worthless to their aims. In a similar way I’m not a fan of zoos, the only way we can really help is by putting more effort into saving habitats rather than breeding a few animals that are not capable to being released into the wild anyway, and then killing them if they are surplus. I agree with the aims of Born Free or PETA for example that aim to help groups that rescue/ care for animals but don’t breed them, as breeding them leads to things like this. 

But hey, quite a few people seem to disagree with me! What does everyone else think?