Weende analysis (proximate analysis)

Relevant for 150 years

The method was developed in 1866 by Hennberg and Stohmann in the German town of Weende. This method is also known as "proximate analysis" and has been used for more than 150 years.

There are several reasons why this analysis is still relevant after such a long time. For example, the analysis is relatively simple, inexpensive and can be carried out routinely. In the past, much animal feed research has also been done with the Weende analysis. Using the same method as previous studies makes it easier to compare results.

It has also been decided by the EU that animal feed need to include the information about  the minimum content of protein and fats. And must state the maximum content of crude fiber and ass on the label. These results can all be obtained with the Weende analysis.

The different groups

The Weende analysis consists of six different groups, which are explained below and briefly explained how we arrive at the results.

Moisture

The moisture content is determined by placing the sample in an oven with a temperature of 103 degrees Celsius. If the weight remains constant and nothing evaporates, the moisture content can be determined.

Inorganic substance

This group is also measured by means of an oven. Only the oven used for determining the ashes is 550 degrees Celsius. Due to this high temperature, all organic compounds burn. What remains are the mass and trace elements. AS is also called mineral fraction.

N-containing substance

Protein has a fairly constant content of Nitrogen (16%). By determining the level of nitrogen, you can also calculate the level of crude protein. The nitrogen is determined by the Kjeldahl method.

Raw fat 

To determine the fat, the sample is placed in a soxhlet arrangement. In this arrangement, the fat is extracted with an extraction agent. What remains is ultimately placed in a fume cupboard for 24 hours so that the extractant can dissolve. The only thing that remains is the fat.

Crude fiber 

By boiling the sample in a dilute solution of a strong acid and a strong base, you can determine the crude fiber content. The product that remains after the treatment with he acid and base fluid is the organic substance: crude fiber.

Other carbohydrates

In addition to the crude fiber, several carbohydrates are present. These are categorized into "other carbohydrates". This group is determined with a calculation. Substances such as starch, sugars, vitamins and organic acids occur as other carbohydrates in the Weende analysis.