Don't shoot the spikes or those with 'poorer' antler growth. That yearling spike could still wind up to be a booner at some point. With adequate nutrition, the genetics start showing at around 3.5 years of age. It is better for rack development to manage for a balanced herd and age structure in the buck segment. Set your harvest age and learn to evaluate taking a deer on that basis, then you will see a much greater response in antler size, I guarantee it. That's what I get paid for.