Suggestions on How to Put Weight On (and keep it on) a Hard Keeper

If she has energy - alfalfa will give her more. Also I have had horses prone to ulcers have difficulty with alfalfa.

You say you feed her flakes of grass hay. What type of grass hay? They are not all treated equally.

I believe in keeping the diet simple and have never had trouble other than weight gain.

I will hang a hay bag (high so horses don’t get feet in them) and fill it with either Orchard grass hay or Timothy grass hay. Keep it filled.

Then for supplements I feed a ration balancer for grass hay diets like Progressive or Buckeye or Stam 30. And throw on a few carrots.

That’s it.

If have horses that get loose manure I give a probiotic.

IMHO you just have to be willing to feed more hay…

Some horses do seem to be sensitive to alfalfa and it will make them weird, but for most horses, alfalfa is one of the best avenues to weight gain. In CA, you probably have access to nice big bales of western alfalfa–adding a few flakes of that a day to her diet would be my starting point. Actually, when we were in CA and my moderately hard keeper mare had surgery and lost a lot of weight really quickly, I bought several bales of alfalfa, stuck them under a tarp, and fed those in addition to what she was already getting.

As that same horse has gotten older (she is now 21), I have found that alfalfa (or peanut hay here) and fat are the keys to keeping her weight good. I also started feeding Tri-Amino when her age started to impact her muscle and topline.

A digestive supplement can also really help. Something with probiotics/yeast. Triple Crown Senior, for instance, has probiotics in it already, but some feeds don’t. I had an Oldenburg gelding who would drop weight every fall and spring unless I had him on probiotics, but if he was on them he was fine and even prone to chubbiness.

A few don’t do well on it, and it’s not for easy keepers, of course, but alfalfa is quite beneficial for many horses, particularly at shows, as it has natural buffers that protect against ulcers.

http://www.thehorse.com/articles/20839/alfalfa-hay-reduces-ulcer-severity

A horse that longs to my boarding facility is a very hard keeper. He is an ancient Arab.
What worked for them was high fat/fiber, flax and veg oil.