"Ash" is the residue left after the food is incinerated in a lab oven, by definition the inorganic mineral content. Most kibble is 5–10% ash; raw and bone-inclusive formulas can hit 10–15%. AAFCO requires ash to be disclosed on the GA when it exceeds the maximum claimed in formulation, but many labels list it for transparency. On a dry-matter basis the displayed protein/fat/fiber/ash/carbs rows sum to 100%; if ash isn't on the label we estimate 7% as-fed (a typical kibble value) so the dry-matter calc has all components. High ash isn't bad on its own — it's a function of how much bone or organ meat is in the recipe — but it does displace digestible nutrients in the same kcal budget.