Which Purina feed should my horse be on?

I'm leaning towards switching my horses feed to the Purina brand, because I don't think the feed she's on right now is the most healthy.. I just need more information about the Purina feeds though..So give me your input..the only options brand-wise are Nutrena and Purina.. Thanks :) Info about... show more I'm leaning towards switching my horses feed to the Purina brand, because I don't think the feed she's on right now is the most healthy.. I just need more information about the Purina feeds though..So give me your input..the only options brand-wise are Nutrena and Purina..
Thanks :)

Info about her::
-10 years old
- QH Mare
-Begining jumping training
-Ridden 3-6 days a week for about an hour each time
-She's on grass 24/7 w/ a flake of hay
-2 Quarts of Nutrena Sweet Horse 12 currently
-She's a healthy weight now
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