Composition is not nutrition
Two ingredients with the same proximate analysis can perform very differently. Processing intensity, anti-nutritional factors, fibre matrix and particle size all move digestibility while leaving the proximate profile unchanged.
Practical proxies for buyers
Full digestibility trials are impractical per shipment. Buyers use proxies: protein dispersibility index and urease for soy products, pepsin digestibility for animal proteins, reactive lysine for heat-processed proteins, and starch gelatinisation for extruded materials.
What to verify
- —Which species and life stage the digestibility coefficient refers to
- —The proxy test result relevant to the process route
- —Whether the value is measured, predicted or copied from a published table
Typical risks
- —Overestimated nutrient supply in the formulation matrix
- —Batch-to-batch variability that averages out on paper but not in the barn
Common mistakes
- —Transferring poultry coefficients to aqua or swine diets
- —Assuming digestibility is stable across origins and seasons
Frequently asked questions
Can digestibility be written into a purchase contract?
Directly, rarely. In practice buyers contract the measurable proxies — urease activity, KOH solubility, pepsin digestibility, reactive lysine — which correlate with digestibility and can be verified on a sample.
Related topics
The amino-acid profile — and above all digestible lysine, methionine, threonine and tryptophan — is what protein ingredients are actually bought for in modern formulation.
Particle size distribution governs mixing homogeneity, pellet quality, digestive efficiency and segregation risk, and is specified as a geometric mean diameter with a distribution, not a single sieve figure.
Crude protein is nitrogen content multiplied by a conversion factor (usually 6.25); it estimates total protein but says nothing about amino-acid quality or digestibility.
Build a structured RFQ with the parameters, tolerances and verification steps written in — free for buyers.
Start your RFQTechnical parameter names and analytical method references are kept in English because they are quoted verbatim in contracts, certificates and international standards.
Educational reference. FeedMatch Group does not rank, recommend or endorse manufacturers.
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