I suggest, before you start buying all this other feed and grains, get her inside's checked first, or start repairing the inner, before you can do the rest.
When I contacted SmartPak and spoke with the consultant, I was going to go with a "Fat Suppliment" like SmartGain and others, but the consultant said don't do it - get the digestive tract going in the right direction first, then move forward from there.
Just like hooves - you can put all the topicals you want on the hooves, but that isn't going to repair the growth or change the angles, nor make them stronger.............you can shove all the food you want into her mouth, but her body isn't going to process it correctly, nor utalize it efficiantly to help her gain weight and get back to her healthy status...........you have to fix the inside first, before you can get anything else.
Start with the right puzzle piece, to connect the others around it. Contact SmartPak and talk to them about their digestive aids. Like SmartDigest Ultra, and SmartGut Pellets.
I really like Purina Products. I personally like the complete feeds, where you can get it all in 1 package, without buying this and buying that and mixing this with that and dealing with all that time consuming nonsence.
I like my Purina Senior. I really like it. I also like Purina Ultium, and I also like their new product Purina Strategy Healthy Edge.
Ultium and the Purina Strategy Healthy Edge are Beat Pulp Based, so you're already getting the beatpulp there, plus many other positives. Both my Veterinarians highly recommend the Purina line, and of course they recommended these to me already knowing about my TB gelding and his health issues and his needs.