Many feel you need 1000 ft lbs of energy to kill a deer or other critter , so look at a chart of what ever round you hunt with and see at what yardage you fall below 1000 and restrict your shots accordingly ! that is if you agree with the idea .
I've used 1,000 FPE for deer and 1,500 FPE for elk as the a rule-of-thumb with good results for many years - So I do agree!