ISO 6496:1999

Overview

ISO 6496:1999 specifies a standardized laboratory method for the determination of moisture and other volatile matter content in animal feeding stuffs by loss-on-drying. The method is based on measuring the mass loss of a test portion under defined drying conditions and is intended for routine quality control and official testing of most feed materials, with specific exclusions (see Scope).

Key topics and requirements

• Scope & exclusions: applicable to most animal feeding stuffs except milk products, mineral substances, mixes with significant milk/minerals (e.g., milk replacers), feeds containing humectants (e.g., propylene glycol) and certain single materials for which other ISO methods apply (fats & oils, oilseeds, oilseed residues, cereals, maize).
• Principle: loss of mass of a weighed test portion after drying; result expressed as a mass fraction (%) of substances lost on drying.
• Apparatus & materials:
  • Analytical balance (readability 1 mg)
  • Non‑corrodible or glass containers with tight lids
  • Electrically heated oven: 103 °C ± 2 °C
  • Vacuum oven: 80 °C ± 2 °C, capable of pressure < 13 kPa (with dried air admission or CaO desiccant)
  • Desiccator and acid-washed sand (for liquids/pastes and high-fat samples)
• Test portions and procedure:
  • Liquids/pastes and oil/fat-dominant feeds: ~10 g mixed with sand in container
  • Other feeds: ~5 g spread evenly in container
  • Dry at 103 °C for 4 h ± 0.1 h, cool in desiccator and weigh
  • For samples showing potential chemical change, an extra 2 h check or use vacuum drying at 80 °C/13 kPa for 4 h, with additional 30 min cycles until mass change ≤ 0.2% between weighings
• Replicates & result reporting:
  • Two determinations from the same test sample; report the arithmetic mean if the two results differ by ≤ 0.2%
  • Final result expressed to the nearest 0.1%
• Precision: annexed interlaboratory data provide repeatability (r) and reproducibility (R) values for several feed types

Applications and users

ISO 6496 is used by:

• Feed testing laboratories and contract analytical services
• Feed manufacturers for in-house quality control (moisture specification, processing control, shelf-life)
• Regulatory bodies and certification agencies requiring standardized moisture determination
• Research institutions studying feed composition and storage behavior

Practical uses include verifying product compliance, adjusting formulations and drying processes, and ensuring consistent feed quality.

Related standards

• ISO 6498 - Preparation of test samples (animal feeding stuffs)
• ISO 6497 - Sampling (recommended sampling method)
• ISO 662, 665, 771, 712, 6540 - alternative moisture/volatile matter methods for specific materials
• ISO 5725-2 - precision (repeatability and reproducibility) test methods

Keywords: ISO 6496, moisture determination, animal feeding stuffs, volatile matter, loss-on-drying, feed quality control, drying oven, vacuum oven, repeatability, reproducibility.