ORIGINAL: dukemichaels
In general terms.. this question is nearly impossible to answer due to so many variables which occur in the wild. Nutrition on a year to year basis can play a huge role in determining this factor.. as well as some other important pieces of his envirornment.
However.. generally speaking... and according to most biologists.. a whitetail buck's peak weight is actually at 4.5 yrs. And his peak antler size is generally at 5.5 yrs.
But again.. take these years with a grain of salt.. since so many other variables can come into play. And I've read different biologists finding slightly different results.. but these years are the norm.
(Peak is refering to the greatest gains at which weight and antler growth is achieved.. but does not neccasarily mean greatest weight and antler size.)
I would believe that the meaning of "peak" would be up to the original poster (it's his thread). In this case I believe he meant heaviest weight and largest antlers. In which 6 1/2 would be closer to the truth. I know one thing, they maintain weight or gain a little more as they age, even past their prime. But, at 6 1/2 they're pretty much at their "peak" weight and antler size. Their are always exceptions to the rule.
Here's a pic of one at his peak.
