If human slaughters an animal to survive then this isn't the same thing as making some animal suffer for someone taste buds. If the animal doesn't suffer before his life is being taken then it still remains an injustice as an innocent animal who was enjoying life got his life taken away by a human. This is something most people try to avoid thinking of and don't like to admit.

It's important to mention the suffering and the injustice of these situations.

What is just doesn't depend on who the supposed victim are it depends on the actions of the person in questions. Animal are innocent victims. If we were in their skin we'd rapidly and undeniably understand this.