There are regulations in place worldwide for the determination of crude fiber content. Standard procedures are applied such as ISO 6865:2000, ISO 5498:2000 (AOAC Official Method 962.09) AACC method 32-10.01, etc.
Crude fiber determination is an element of the classic Weende feed analysis. For crude fiber determination the sample is – if required degreased – treated successively with boiling acid and alkaline dilutions in the prescribed concentrations. Following filtration with a sintered glass filter, the sample is washed, dried, weight and incinerated at 475 … 500 °C. The weight loss during incineration corresponds to the crude fiber content of the sample.