NAF General Purpose Supplement Refill Perfect for horses in light to moderate work, NAF General Purpose Supplement offers a broad spectrum of vitamins and minerals perfect for keeping your four legged friends happy and healthy. Although forage provides a high fibre diet that mimics a horses natural diet it may not contain all the vitamins and minerals needed to ensure your horse gets everything they need. With a broad range of vitamins and minerals available, NAF General Purpose Supplement is designed to complement the high fibre, low concentrate diet or those receiving less then the manufacturers recommended rates of hard feed.