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Acid Detergent Fiber (ADF), Lignin (Ash Free), Acid Detergent Insoluble Nitrogen (ADIN), Total Digestible Nutrients (TDN) And Cellulose - Reflux Method

ADF, ADF (Ash Free), Lignin (Ash Free), ADIN, TDN, Cellulose


This procedure is used for the determination of acid detergent fiber (ADF) and ADF-derived tests including lignin, cellulose, TDN (total digestible nutrients) and ADIN (acid detergent insoluble nitrogen) in all types of forages. A hot, acidified detergent solution is used to dissolve cell solubles, hemicellulose and soluble minerals leaving a residue of cellulose, lignin, and heat damaged protein and a portion of cell wall protein and minerals (ash).

Sample amount requested:  20 g

Questions concerning limited sample size can be answered by the UC Davis Analytical Laboratory.

ADF is determined gravimetrically as the residue remaining after acid detergent extraction. Lignin is determined gravimetrically after the ADF residue is extracted with 72% H2SO4 and ashed. Cellulose is determined by subtracting the pre-ash lignin value from the ADF value. TDN is a calculation based on the ADF value and is reported based on the formula for alfalfa. The TDN result is standardized to a 90% dry matter value. ADIN is determined by nitrogen analysis (combustion) of a sub-sample of the ADF residue. (See SOP 525 for information on nitrogen analysis.)

Analyte Typical MDL
ADF 0.5 %
Lignin 1.0 %
Cellulose 1.0 %
TDN (@90%DM) 0.5 %
ADIN 0.05

AOAC Official Method 973.18, Fiber (Acid Detergent) and Lignin in Animal Feed, in Official Methods of Analysis of AOAC International, 16th edition (1997), Chapter 4, pp. 28-29, AOAC International, Arlington, VA.