Animals are killed with far less energy than the .357 Mag or .45 Colt provide every year, just look at bow hunting for example. Energy is just a byproduct of velocity and mass, it never indicates how well a cartridge will kill. The only thing you need to really worry about is, can I put the bullet where it belongs? Don't get me wrong you need a certain amount of energy transfer to make things work properly, but nobody has produced to date a definitive study of how much energy is needed to kill a deer.
The only energy figures I care about is the one that is set in the Colorado big game hunting regulations. Rifles must produce 1000 ft. lbs. of energy at 100 yards, and pistols must produce 550 ft. lbs. at 50 yards. Unfortunately that leaves both the .357 Mag and .45 Colt in the cold and unusable as either rifle or pistol.