Ash Levels in Dog Food

[quote=jebel321]What causes higher levels of
ash in dog food?[/quote]

Basically dietary ash is what's left over when food is burned (just like ash in your fireplace is the non-combustible wood). This is an indigestible portion of the diet. In general the lower the ash content, the better the diet can be absorbed. In a natural diet most of the ash would come from the minerals in the bone.

This article http://www.mercola.com/2005/mar/2/pet_food_labels.htm should also help you understand ash and its' role in pet food.