It certainly doesn't sound appealing: Ash in your dog's dry food? No, that sounds gross. Many people mistakenly believe ash is a pet-food filler to cheapen the cost of production. But a food's ash content actually represents its total mineral content. Organic ingredients with calories -- protein, fats and carbohydrates -- can be incinerated; the inorganic mineral content would be all that remains, in the form of ash.
Since ash content signifies mineral content, including calcium, phosphorous, iron, zinc and others, dry pet foods should have ash content. And all do. The typical ash content in high-quality commercial dry dog foods is 5 percent to 8 percent. It's no coincidence; this is the generally accepted ideal range. That said, ask your veterinarian whether your large-breed puppy or dog with kidney dysfunction or other urinary tract problems should eat a dry food with lower ash content.
So, there's a standard ash content range, not a single percentage. That's because ash content varies a bit depending on the ingredients. For example, high-protein formulations contain more meat and bone, which raises mineral quantities and therefore ash quantities. Foods with supplemental minerals also have a higher ash content.