Crude ash

Crude ash is the mineral residue that remains after a food sample is fully incinerated, and it serves as a simple proxy for the food's total mineral content, including calcium and phosphorus. The name often alarms owners who picture something burnt and unwanted in the bag, but that is a misreading: ash is not an added ingredient, it is what is left after laboratory combustion drives off all organic matter, leaving only the minerals behind (FEDIAF, 2024). A higher ash figure therefore signals a higher mineral load, which is frequently linked to the presence of bone or [meat meal](/glossary/meat-meal) in the recipe, since these are mineral-dense ingredients. This is genuinely informative for certain animals. In cats, ash and the related calcium-to-phosphorus and magnesium levels are relevant to lower urinary tract health, which is why feline [neutered diets](/glossary/neutered-diet) and some [indoor](/glossary/indoor-diet) formulas pay attention to mineral balance. A useful caveat is that ash alone does not tell you which minerals dominate or whether their ratios are appropriate, so a sensible amount of ash from quality animal ingredients is not a defect, whereas an unusually high figure may warrant a closer look at the [ingredient order](/glossary/ingredient-order). It appears in the [analytical constituents](/glossary/analytical-constituents) list and feeds into the [NFE carbohydrate estimate](/glossary/carbohydrate-estimate-nfe). For more on decoding the mineral side of a label, see the [Petipedia glossary](/glossary).

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