Originally Posted by Gammelquarterhorses
In my area there is a lot of iron already in the well water so you need to be careful and research all suppliments that you want to give. You don't want your horse to recieve too much of one mineral or vitamin, it can have a bad affect.
Also how long have you been training this mare? I think if it's been for a while I would take her out on a long trail ride or just give her a break. I have found that when I gave my western pleasure horse a break from the normal routine, he would give me 100% the next lesson.
I very much agree, especially with the bold.