Food, water, stress, maturity all play roles in the antler growth but nothing is more significant than genetics. A dink bucks offspring will always be just that, while a trophy deer will produce trophy racks...sure year to year growth is suspect to the other conditions but the underlying factors is if he has the genes and is allowed to grow to that potential (maturity) he will have trophy qualtity horns. If you strap the best conditions and feed bag onto a deer with inferior antler genetics he will not be a trophy...plain and simple. So genetics plays a much bigger role than "I guess" when it comes to deer.

As to your question about 3 years olds weight and antler score that is also dependant on the same factors. While maturity isn't usually achieved till above this age which is when the bucks reach peak antler growth, cases such as the hansen buck do appear. Clearily this is a statement to this deer's excellent genetics to grow such tree trunks at the young age of 3 and should be viewed as the exception not the rule. I'd say it would be 120-140 score wise and 175 lbs fully dressed as guessed average for sask.