How is reliable and consistent forage analysis ensured?Our member labs collectively analyse around 70,000 samples of grass, maize and whole cereal silage annually. It is important for farmers and feed advisers to have nutritional reports that are reliable as decisions on animal feed rations will be based upon them.
Silage is a variable material by nature and further variation can be introduced by the way samples are taken on farm from bag, bale or pit; the method of transfer to laboratory and handling upon receipt; preparation of sample for testing and operation of the testing equipment.
The Proficiency Test Scheme provides each member with a set of standardised test samples every month from summer to late spring. These, in turn, are assessed to ensure the samples are homogenous and each lab is receiving the same sample.
Each laboratory analyses the samples according to their normal commercial method and reports the results to the group. The results are then statistically reviewed and compared to two standards..
- Firstly, against a Master NIRS Instrument (NIRS is Near Infra-red Spectroscopy) and is a widely used rapid technique for forage analysis in laboratories and on farm.
- Secondly, against the gold standard of wet chemistry analysis carried out by an ISO accredited laboratory.
Having both these sets of results allows the laboratories to confirm that their instruments are calibrated and performing correctly and that the rapid analysis techniques are a good reflection of wet chemistry results.
From agreed key nutrient data, the member laboratory’s performance is graded. Over the year a picture builds up to show how reliable and consistent their analyses have been, and if there are any problems, then action can be quickly taken.
Different forages have different characteristics – for example, grass silage is much more uniform in character than whole crop or maize silage due to the inclusion of stalk, leaf and grain. Inclusion of all types within the Proficiency Testing Scheme demonstrates that laboratories are applying consistent techniques in sample preparation and measurement to all forage samples.