Crude fibre in roughages

Crude fibre in roughages is > 18%.
Crude fibre is the insoluble residue of acid hydrolysis followed by an alkaline one. This residue contains true cellulose and insoluble lignin. It is also used to assess hair, hoof, or feather residues in animal by-products.
The National Research Council classifies a roughage as a feedstuff with a minimum crude fiber content of 18% and a maximum content of total digestible nutrients (TDN) of 70%. Roughages provide a range of nutrients to animals.