Best grain/feed for weight gain.
I recently got a poor little filly who is underweight. She wasn't being fed enough by her previous owner and was in sad shape when she came to me. I've had her for a little over a month now, and she has gradually started gaining on quality grass/alfalfa. I didn't want to put weight on her too quickly, because I know its important to be careful and gradual. She is stable enough and eating well, and has been wormed correctly. I want to start her on some additional feed to help her gain some added weight.
For most of my horses, I feed COB, and they sustain well, but I'm not liking it so much as I'm realizing how much of the whole grains go unused by the body. Some of my horses rush through eating their grain, and grains that are swallowed whole tend to pass right out in their poop, being wasted. Someone suggest beet pulp. I know it must be soaked before feeding. But the dangers of expansion still worry me. Another friend suggested rice bran because it is utilized better than whole grains and is less complicated or worrisome as beet pulp. Still another suggested mixing the two.
What do you think is better? And how much do you think I should feed? She is 1 1/2 years old, so she is growing, and she is a National Show Horse (arab x saddlebred).