Practical tips for sampling

08 March 2016

Every GMP+ certified producer of trader of feed must take samples of its products. This is done primarily as part of the traceability system. These samples must be retained and are investigated when there appear to be issues with the feed. In addition, samples are also taken and analyzed in the context of monitoring and verification (part of the HACCP steps).

In this newsletter, we address several items about the sampling.


It is important that sampling takes place in a correct manner and that representative samples are taken. This, together with properly conducted analytic investigation, contributes to reliable analysis results. This way, the right conclusions can be drawn regarding the quality and safety of the produced or delivered feed.

The GMP+ B1, B2 and B3 standards contain requirements for sampling, with reference to GMP+ appendix BA13.

Retention samples

With regard to taking samples in the context of traceability, the GMP+ standards are in line with European legislation. Samples of both incoming and outgoing feed products are taken. These samples are referred to as ‘retention samples’.

Retention time

Please make sure that the samples are retained sufficiently long. The GMP+ requirements have adopted the formulation from the EU legislation in this regard. The samples must be retained at least ‘during a period appropriate to the use for which the feed is marketed.’

For GMP+ companies, this requirement means that they must retain the samples at least until the feed product has been fed. Sometimes, a lot of time passes between the production of a feed ingredients and the moment of consumption by the animals. As a producer of feed ingredients, please also observe the time of the transport (such as sea transport), any temporary storage (in a port or a silo elsewhere), the turnaround time of processing at compound feed producers and the feeding of the compound feed at the livestock farmer.

GMP+ BA13, chapter 4, provides a table with minimum retention periods. These should indeed be considered minimum retention periods. It may sometimes be necessary to observe longer retention periods.

Sealing and storage

The samples (and with that, the retention samples) must be sealed. There are various possibilities to do so. The goal is to rule out any misunderstandings about the integrity of the samples. Keep in mind that the competent authorities may request these samples if there is reason to do so, but GMP+ International as well. GMP+ certified companies are required to comply with such a request.

Samples in which any micro organic analysis may be carried out, must be taken and packaged in a sterile manner.

Storage of samples must be as such that the sample remains suitable for the purpose for which the sample was taken. Any analysis of the sample must provide reliable results. Retaining a sample in a cool and dark environment often keeps the sample in the proper, required condition. It goes without saying that pests must be barred from the sample storage area.

GMP+ requirements for sampling

Sampling must be done in accordance with standard procedures. The sampler must meet a number of qualifications, including knowledge of the feed, knowledge of the protocols and experience with taking samples (education!).

GMP+ appendix BA13 provides protocols for various situations. Important topics addressed in every protocols include:

  • Place of sampling;
  • Equipment: clean, reliable and if required: sterile;
  • Number of sub samples and the way a final sample is made;
  • Minimum amount of sample material: there must be enough to be able to carry out relevant analyses;
  • Sealing, storage and storage conditions (also see 2.2.2);
  • Minimum retention period (please also see 2.2.1);
  • Identification and registration of the samples.

Testing whether these components are complied with must be addressed during the internal audit and during the testing of the recall procedure.

Points of attention

  • As previously indicated, samples are also taken in the context of the monitoring and verification plan. This means that these samples are taken for the purpose of analysis. The purpose of that is to assess whether the risks identified in processes and products (including possible risks at earlier links) are controlled. And that the feed meets the specifications as defined. It goes without saying that poor sampling, regardless of expertly performed analysis, can never provide a reliable result. All the more reason to pay attention to proper sampling.
  • Assessing the way samples are taken, must be part of the annual internal audit.
  • Do not forget! Including the sampling of processing aids in the sampling plan.
  • There are traders that do not physically store or process feed. Still, these trading companies have the (legal) obligation to take (retention) samples. However, the GMP+ requirements allow for these trading companies to make arrangements with their suppliers or customers about sampling. In this, it is important that these samples are available.

Sign up for the GMP+ International newsletter

Stay up to date with the latest news