TDN in crude fibre is

TDN in crude fibre is < 60%.
The energy value of forage is expressed as total digestible nutrients. Typically, the greater the value, the more energy-dense the forage is considered. Low-quality hay is generally 45 to 52% TDN.
TDN is determined by multiplying the digestion coefficient for organic matter, D, by a conversion factor calculated by the formula: F = M (0.01 + 0.000125 E) where M is the percent organic matter in the dry matter of the feed and E is the ether extract as percent of the organic matter.