Stability Testing of Animal Feed

Evaluation of stability of e.g. active ingredients, in animal feed

during storage at pre-determined temperatures and relative humidity contents.


Additives in animal feed should be distributed homogeneously. This is mainly realized by the use of a premix with a high concentration of active ingredients. Premixes consist of an excipient with one or more active ingredients as trace elements, vitamins, nutrients, amino acids or medical products. To ensure continuous high activity and to avoid degradation, stringent conditions for their storage are usually necessary. Depending on the components a premix can be sensitive to environmental factors as temperature, humidity, oxidation, light, shear but also the overall composition with metal elements, and oxidising or reducing components.


Storage Conditions

Evidence is necessary to demonstrate the stability of the premix before incorporation into an additional feed. The shelf-life specification of a premix includes stability indicating test parameters.

The thermal stability and sensitivity can be evaluated under frequently-applied storage conditions as for instance temperatures at 25 °C, 30 °C or 40 °C with RH of 60%, 65% or 75%.

Others storage conditions during handling and shipping can be tested at specific temperatures and relative humidity’s in accordance with customers’ requirements.


Testing is carried out using the final packaging materials. For this purpose, small scale comparable containers or bags are used.


Testing Frequency

Selected testing intervals are sufficient to establish the stability of the product over the required time period. Including initial and final points in time, the samples are analysed at pre-determined time points, depending on customers’ requirements. Analysis of active ingredients can be done according to customers’ needs in specialized laboratories.


Testing Procedures

Testing procedures cover all relevant aspects which may change during storage and which may likely affect the quality of the product. These include physical (dustiness, particle size distribution, flow ability) or chemical (activity, transformations) characteristics, which may change during storage.

On the whole, there is no single stability-indicating assay or parameter that profiles the stability characteristics of a product. In consultation with the applicant a stability-indicating profile is prepared.


A (non-comprehensive) list of available methods is given below;



(Trace) Elements

by Neutron Activation (ISO-IEC 17025) and X-Ray Fluorescence (XRF)






EN15051, DIN55992 according to EFSA and U.S. EPA OPPT.


ASTM D6393, D6128, D6773.

Particle size distribution

ISO13317, 13319, 13321, NPR2244.

Specific surface area

ASTM D4222, D3663, D5604, D4780, ISO9277, ISO15901.


Additional analytical procedures and aspects, such as microscopy (optical or SEM), visual appearance of the product, pH, moisture level, water adsorption, caking, density, pore volume, and segregation are possible.


The tested products in bags or generated dust from the product can also be returned to the applicant for subsequent “in-house” testing.


Stability Study

The stability studies can be conducted in accordance with the various conditions as put forward by international regulating bodies such as the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products (VICH) or EFSA (European Food Safety Authority)



In collaboration with the applicant, a premix or product of active ingredients and excipients for the animal group and age is composed, homogenized and divided into representative lots for controlled storage and subsequent testing of physical, biochemical and or chemical aspects.


"Significant change" at the accelerated condition is defined as failure to meet specifications. Results out of specifications are reported directly when established at a test interval. A full statistical set-up and evaluation is part of the procedure.






Zetadec B.V.

Zetadec is a consultancy and contract R&D organisation for the feed, food and biomass industry. The strongpoint of Zetadec is its ability to operate on the interface of raw materials on the one hand and (processing) technology on the other hand. We assist companies in transforming new ideas into added value products.




Agro business park 44

6708 PW Wageningen

The Netherlands


Phone       +31 317 479644

Fax            +31 317 479666

Mobile      +31 620426959









Delft Solids Solutions B.V.

Delft Solids Solutions is a contract research organisation specialised in the physical characterisation of solid materials. The well-equipped laboratory coupled to the high degree of expertise guarantees high quality research and results that can be delivered in due time.



Main Office                                         

Rotterdamseweg 183c, 2629 HD Delft

P.O. Box 1038, 2600 BA Delft

The Netherlands

Phone      +31 (0)15 268 25 16

Fax           +31 (0)15 268 25 30





Bijdorpplein 21-23

2992 LB Barendrecht

The Netherlands

Phone      +31 (0)180 622 500

Fax           +31 (0)180 623 500