Horse Health Vita B-1 Crumbles Horse Supplement offers an easy-to-feed source of vitamin B to support your horse’s health. This supplement is ideal for horses in strenuous exercise. Vitamin B-1 supports muscle function and a calmer demeanor in your nervous Nellie, and each serving contains 500 milligrams of vitamin B-1. Larger crumbles help to prevent sorting and make for easy top dressing.