Purina Strategy Healthy Edge is a low starch/sugar formula for horses who are in moderate work, but need lower calories than others. It's also not crazy expensive ($18 per bag where I live). Y vet recommended it, so I've been using it on my 14 year old jumper who's an easy keeper for years and it's good for her! She's also out to pasture all day. You also don't have to feed it bulk, which is nice.
Triple Crown Low Starch is the same formula, but I think it's $4-6 more expensive per bag than the Healthy Edge (my feed store quoted me $23).
There are other good grains out there, I'm just a big fan of Purina and Triple Crown...when I can afford it! Lol
Oh, and here's the link to Purina's products: http://www.horse.purinamills.com/products/Default.aspx
And here's the link to Triple Crown: http://www.triplecrownfeed.com/produ...-horsefeedcost
They've got loads of info on all of their feeds!