640 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
Determination of the amount of acid detergent fiber and lignin in feed materials using acid detergent, sulfuric acid and heat.
Summary: 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). The analyses require approximately 10 g, but a minimum of 20 g is requested to allow for quality control samples.
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.