I have a 17 year old stallion that is terrible trying to keep weight on. After a year of trying out different feeding regimes, this is what he gets: 3 1/2 pounds of senior feed in the morning and at night. With that he gets 1/2 pound of rolled oats, 1 tablespoon of vegetable oil, and 2 cups soaked beet pulp. That's each feeding. He is also fed free choice grass hay that has a little bit of alfalfa here and there as well. Everytime I feed him I think, oh myy goodness this is so much! But he is not fat at all and this is the only thing that has worked for us. I think the beet pulp does a lot for him-finally added weight to his topline. And the veggie oil has given him a gorgeous coat plus adds a few calories. Sometimes with the older horses you have to try a few different things before you find what works best. I'd add the beet pulp and oil to your girls diet to start with, I bet you'll see a change!
**(my stallion is 31" so you can compare)**
**(my stallion is 31" so you can compare)**