The method determines ash-free NDF and includes amylase for starch removal and sodium sulphite for protein removal. This is commonly denoted aNDFOM, where “a” stands for amylase and OM for “organic matter” (everything that is not ash). In the final calculation, the weight loss during ashing is the ash-free NDF (the NDF that is combusted, leaving only the ash). The equation is: aNDFOM(g/kg) = 1000*(V1-V2)/sample weight (g) V1 = weight after extraction and drying (g) V2 = weight after ashing (g)