I much prefer the Taylor Knock Out scale when talking about killing big game.
http://www.n4lcd.com/calc/
Paper foot pound of energy do not really mean much, since big game critters are killed by blasting holes through hide, fur, bones and various eternal organs.
For instance my 50-90 shoots a .511 caliber, 615 grain lead bullet at 1,400 fps. It only has around 2,700 ft pounds of muzzle energy and at 600 yards drops below the 1,000 ft pound energy mark you are using. But the bullet is still going around 875-900 ft per second at that range.
Oddly enough this also happens to be the same paper energy that the 223 Rem develops with a 55 grain bullet at around 75 to 100 yards when fired from a full length M-16 barrel.
So which will blast through several inches of bone, meat, fur, hide heart and lungs??? The 223 at 2900 or the 615 grain 50 caliber lead bullet at 875 ?????
By the way the Taylor Knock Out value for the 50-90 at 600 yards is a #38, while the 223 Remington is a #5 at the muzzle.
This is why old time Alaskans like my dad and grandpa used 220 grain bullets in their 30-40s and 30-06s...for Brown bear and most moose hunting. The may be slower, but they punch through like a freight train and make lots of holes through multiple organs.
That is also why I use 275 to 280 grain bullets in my 350 Rem Mag loaded to a moderate 2,400 fps. Plus solid 400s in my 416 Taylor.
