Well, there are some variables that come into play, which would make the answer vary also. However, in Hatcher's Notebook, I find (p407-408), that the 30-caliber, 150-grain M2 Ball bullet, striking at 140 FPS, carries 100 foot-pounds of energy, and this was considered the minimum velocity/energy level to inflict a wound on the human body. It does not say what the extent of such a wound would be, however.

Deer and hogs were not mentioned.....

(I still continue to be tickled by the guys who maintain - a lot of whom should know better-that it takes "X" foot-pounds of energy to kill a deer, a bear, an elephant, etc., and never qualify their claims at all by describing the type and size of the required projectile! Let's say it DOES take 1000 ft/lb to kill a 150-pound whitetail buck. If that's true, then what is required to kill a 7.5 ton bull elephant? Here we need 6.6 ft/lb per pound to kill the deer. Does it likewise require 6.6 ft/lb per pound to kill the elephant? If so, we need a bulletthat impacts with 99,999 ft/lb! Now, I seriously doubt that anyone here would care to fire it, even if such a rifle existed! For the sake of comparison, lets use an elephant rifle that delivers8000 ft/lb of energy at the elephant. If this is enough to kill the 15,000 pound elephant, that's only 0.53 foot-pounds of energy per pound of elephant! Deer are therefore 12.375 times more difficult to kill on a pound-for-pound basis than elephant!

I suspect that even if the "foot-pounds of energy" figure is useful for comparing rifles that fire bullets of similar diameter and construction, it is NOT useful in determining what is required to kill various game animals. For example,I have a .73-caliber Jaeger rifle that fires a .735", 597.5 grain pure lead round ball at a MV of 1600 FPS. I would be willing to bet that this contraption will kill a moose or elk just as quickly, within 100 yards, as a 7mm Rem. Mag. that carries almost twice the foot/pounds of energy, given identical points of impact on the game.)