Only to eat. Before going out to hunt there are rituals and prayers, and immediately after the kill, we offer prayers thanking the animal for allowing itself to be killed so that we may continue to live. I realize this may seem hypocritical to many, but it's just our way. Once the animal is killed, we use as much of it as possible, wasting little, out of respect for it's life, and the loss of it. For example, meat is eaten, hide is used for leather for clothing, sinew for thread, bones for tools, hooves for glue and rattles (for ceremony). Even the eyes can be used as the fluid in the eyes makes a most wonderful varnish... Horns for handles for knives, etc. Granted, most people, even many natives, don't follow these guidelines. Many, like myself, still follow the traditional ways. I make no judgements on the ways of others, this is just the path some of us follow.