NAF Biotics Supplement. NAF Biotics Supplement is a unique combination of pre and probiotics designed to maintain healthy gut function. NAF Biotics contains live yeasts to support gut health and fructo-oligosaccharides to support the growth of micro-organisms in the digestive tract. The pro and prebiotic ingredients work in harmony to support healthy, natural and normal digestive function. NAF Biotics Supplement is ideal for hard working horses, competition and performance horses, horses recovering from antibiotic treatment and horses and foals prone to digestive upset.