NDF/ADF Analysis
Neutral Detergent Fiber and Acid Detergent Fiber Analysis · Also known as: fiber fractionation, detergent fiber analysis, forage quality assessment
Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) analysis is a chemical fractionation method that separates feed components into digestible and indigestible portions based on their resistance to sequential detergent treatments. Developed by Peter J. Van Soest in the 1960s, NDF/ADF analysis provides rapid estimates of forage quality and feed digestibility, making it fundamental to ruminant nutrition and feed evaluation worldwide.
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When to use it
NDF/ADF analysis is applied to characterize forage samples before purchase or feeding, to monitor quality changes during storage (ensiling, hay weathering), and to assess the effects of harvest timing and processing on feed quality. In research, NDF and ADF are used to explain variation in animal performance and to study factors affecting cell wall digestibility (breed, genetics, plant maturity). The method is standard in feed evaluation programs and is integrated into most ration formulation software.
Strengths & limitations
- Rapid analysis (same day) compared to weeks required for in vivo digestibility studies
- Provides fiber fractionation directly relevant to ruminant nutrition and filling effects
- Standardized protocols enable consistency and comparison across laboratories and studies
- Economical; minimal equipment and expertise required relative to bioavailability methods
- Strong relationships with digestibility and animal performance in published regression equations
- Model predictions based on regression equations; accuracy varies with forage type and growing conditions
- Sequential detergent treatment introduces analytical error; residue from NDF becomes input for ADF, propagating errors
- Does not account for the effects of processing (grinding, pelleting, heat) on digestibility within the same fiber fraction
- Cannot distinguish lignin from other acid-insoluble components (silica, minerals), overestimating lignin in certain forages
- Prediction equations developed in different regions or production systems may not apply universally
Frequently asked
Why is NDF higher than ADF?
NDF includes cellulose, hemicellulose, and lignin. ADF includes only cellulose and lignin. The difference (NDF - ADF) is hemicellulose. Hemicellulose is a significant component of plant cell walls and generally more digestible than cellulose, so NDF will always be higher than ADF in plant materials.
Can low NDF forage be too low for ruminants?
Yes. Ruminants require minimum NDF (typically 25-30% of diet dry matter) to maintain normal rumen function, rumination, and gut health. Very low-NDF diets (from high-concentrate feeds) can cause rumen acidosis. A balance between digestibility (low NDF) and sufficient structure (minimum NDF) is necessary.
Does NDF digestibility vary?
Significantly. NDF digestibility (the percentage of NDF that is actually digested) ranges from 30% in low-quality forages to 90% in high-quality fresh pasture. This variation is driven by lignin content (lignified cellulose is indigestible), plant species, and maturity. Two forages with the same NDF concentration can differ substantially in digestibility.
How does harvest timing affect NDF and ADF?
As plants mature, cell wall content (NDF and ADF) increases while cell contents (proteins, sugars) decrease. Early-harvest forages have lower NDF/ADF (higher quality); late-harvest forages have higher NDF/ADF (lower quality). Harvest timing is the primary management tool for controlling forage quality in hay and silage production.
Sources
- Van Soest, P. J., & Wine, R. H. (1967). Use of detergents in the analysis of fibrous feeds: II. A rapid method for the determination of fiber and lignin. Journal of the Association of Official Analytical Chemists, 50(1), 50-55. link ↗
- Goering, H. K., & Van Soest, P. J. (1970). Forage Fiber Analysis (Apparatus, Reagents, Procedures and Some Applications). Agricultural Handbook No. 379, USDA-ARS. link ↗
- Mertens, D. R. (2002). Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: collaborative study. Journal of AOAC International, 85(6), 1217-1240. link ↗
How to cite this page
ScholarGate. (2026, June 3). Neutral Detergent Fiber and Acid Detergent Fiber Analysis. ScholarGate. https://scholargate.app/en/veterinary-science/ndf-adf-analysis
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