Finish Line Vitamin B1 Blend Muscle & Nerve Care Powder Horse Supplement, 4-lb tub; The Finish Line Vitamin B1 Blend Horse Supplement provides vitamin B1 to support your horse’s healthy muscle and nerve function. Feeding vitamin B1 may also help to calm nervous horses, making the ride more enjoyable for both of you. This supplement’s apple flavor appeals to even picky eaters, and the powder form is easy to feed—plus it won’t freeze in the winter, unlike liquid supplements! This supplement contains 8,000 milligrams per pound of vitamin B1 (thiamine mononitrate), as well as calcium.