Bullet construction will play a major role but the bottom line is that a few hundred foot pounds is all it takes to cleanly kill a deer sized animal. Most of the so called experts that come up with the charts are far from experts. Most reccomend 1000 for deer and 1500 for elk. Hogwash. You don't need anywhere that amount of energy.

Remember that you only need to get half way in to put a bullet through the heart of an animal.