I eat meat, all of which comes from the butchers these days. The animals and birds are bred for human consumption and I hope that they are all raised and killed humanely. In the past we kept chickens, ducks, geese and rabbits ourselves, all of which had good lives and many of which ended up in our freezer after a quick end, so we are not squeamish.
I know that in nature animals prey on each other. I shall never forget, as a young chap in Africa a long time ago, witnessing the occasion when a lion jumped on the back of a large buck, which reacted by impaling the lion on its long sharp horns and seriously injuring it. One up to the hunted!
The case of Marius the giraffe is different. How any normal person could have had this poor, trusting young creature so needlessly and callously killed and then publicly dismembered is beyond me and sickens me. I would seriously question the activities of the zoo and its management in this case.