How much of the current feed are you giving? How many pounds does the feed bag recommend for her age? It might be as simple as just feeding MORE of what you already have, vs. trying to add in this-or-that. Some feeds, like Senior feeds, do not supply a complete nutritional profile unless you feed 5lbs daily.... Read you label, and most importantly, feed by WEIGHT, not volume. A 1 qt scoop of 5 different feeds can each weigh differently, sometimes up to as much as half a pound more or less than the other, and the nutrition is based on the weight of the feed....
made me emotional for her. 
Unfortunately I had him in a sand pen on the directors jogging path. Bad luck. I heard from her almost every day wanting to put him down. I was feeding him 25lbs a day trying to beef him up. I wanted him thin while we did the corrective trimming ordeal but not skin and bones like he was. It wasn't until I started to top his morning feed (I had to feed him 3x a day) with a little (1/4 cup) veggie oil that he started to gain some ground with his weight. The pain uses up LOTS of calories. Go figure. Nice by product was his coat became amazing.
