I agree with the comments made on grain. This makes a huge difference. I find it best to read the percentages on the feed tags. For the wild ones we feed ultium by purina feed. The key is reduced starch and sugar (those feed the bucks) The fats and fermentable Fiber create focused energy you can work with. This is a feed for performance horses so it wont disappoint.
I have also had great success with Red Cell as a supplement. It gives focused and steady energy.
I hope this helps