Horse is underweight and needs to gain 100 lbs?

Try Weight Builder you can find it online or at Orchelns. The directions for feeding it is on the back of the bucket. I use it on my old mare and it keeps weight on her. ( Made By Farnam) Premium concentrated high calorie supplement for weight gain, body condition and fuel for performance. Traditionally, horse owners fed more grain to provide extra calories, but too much grain can cause colic, diarrhea, founder and other problems. Weight builder contains 40% fat from flax meal and vegetable fats, contains added calcium and is naturally high in Omega-3 fatty acids. It also visibly improves the skin and coat condition. Feed 4 oz. per day.