When hay quality is inconsistent, your horse?s nutrition doesn?t have to suffer. Provide your horse with a consistent and easy-to-use premium forage replacement with IMPACT? HAY STRETCHER Horse Feed. With over 100 years of expertise and research in equine nutrition and a dedicated team of Ph.D. Equine Nutritionists and Equine Veterinarians, nobody knows more about horse nutrition than Purina. Purina? IMPACT? is formulated to deliver premium nutrition with only high-quality ingredients that have been proven through years of feedings to support overall horse health and performance. See the difference IMPACT? feed can make for your horses.