Overview
ISO 16472:2006 specifies laboratory methods for the determination of amylase-treated neutral detergent fibre (aNDF) in all types of animal feeding stuffs. The standard defines both a gravimetric routine method and a reference method to quantify the neutral detergent insoluble fibrous residue remaining after treatment with neutral detergent and heat‑stable alpha‑amylase. aNDF is a key indicator of plant cell‑wall material (cellulose, hemicellulose, lignin) and indigestible nitrogenous matter, used in feed evaluation and ration formulation.
Key topics and technical requirements
- Scope and principle: Use of neutral detergent (ND) solution together with heat‑stable alpha‑amylase to dissolve non‑fibrous components and leave the insoluble fibrous residue (aNDF).
- Reagents: Specifications include sodium sulfite, heat‑stable alpha‑amylase (standardized to remove starch from a reference corn sample), iodine solution and a detailed ND solution composition. Only analytical‑grade reagents and purified water are recommended.
- Apparatus: Typical equipment includes an analytical balance (0.1 mg readability), cyclone/cutter mills (grind to a geometric mean particle size 220–260 µm), refluxing apparatus or Fibertec‑type systems, Gooch/P2 fritted‑disc crucibles and vacuum filter manifolds.
- Sample preparation: Follow ISO 6498 recommendations; samples should be air‑dry (~90% DM) or dried at <60 °C to avoid artefact fibre. Homogenization and controlled grinding are required.
- Procedure highlights: Weigh test portions (~1 g dry equivalent), pre‑extract high‑fat samples (>5–10% fat) with acetone, add sodium sulfite and ND solution, add standardized amylase, reflux (60 min) with vigorous particle movement, then filter, wash and dry residues for gravimetric determination.
- Quality assurance and precision: The standard requires use of blanks and in‑house reference samples, reports repeatability and reproducibility data (see Clauses 11 and Annex A), and includes Annex B on enzyme standardization.
- Safety: The document warns about hazardous materials and the need for appropriate laboratory safety measures.
Applications and users
ISO 16472:2006 is used by:
- Feed testing laboratories for routine aNDF analysis and quality control.
- Feed manufacturers and nutritionists to evaluate forage and compound feeds for ruminant diet formulation.
- Research institutions studying fibre digestibility, feed composition and animal nutrition.
- Regulatory and certification bodies requiring standardized fibre measurement for labeling or compliance.
Practical uses include feed formulation, forage evaluation, comparative analyses across labs, and establishing nutritional specifications for ruminant diets.
Related standards
- ISO 6498 (referenced normative standard) - preparation of test samples for animal feeding stuffs.
- The standard also cross‑references methods and apparatus (e.g., Fibertec systems) commonly used in fibre analysis.
Keywords: ISO 16472:2006, aNDF, amylase‑treated neutral detergent fibre, animal feeding stuffs, neutral detergent fibre analysis, feed testing, Fibertec, Gooch crucible, sample preparation, feed quality control.