按照官方方法进行纤维测定的一致性和准确性

21/07/2022

Discover more about the analytical methods for fiber determination in feedstuff and achieve accurate and reliable results with the VELP Fiber Analyzers.

Feed represents 70% of the costs of a livestock operation. It is made up of many components and it is essential to assess the amount of these elements in order to obtain a nutritionally balanced diet.

Fiber is one of the most important feed components. From a nutritional point of view, it occupies more space in the digestive tract than any other substance because it is poorly digestible.

The fiber amount of feed has an impact on livestock productivity and the cost of the feed. For example, the calculation of the correct amount of fiber in the feedstuff influences milk production, milk quality, and fat content of milk.

Analytical methods fiber determination in feedstuff

Official Methods for Fiber Determination

Since there is no guarantee of direct correspondence between chemical solubility and nutritional availability, fiber is defined by the method used to isolate it.

There are two official recognized methods used today:

1. WEENDE METHOD (CRUDE FIBER)

The method is based on the solubilization (digestion) of non-cellulosic compounds by sulfuric acid and potassium hydroxide solutions. Crude fiber is the loss on ignition of the dried residue remaining after digestion of the sample and is determined by weight difference.

It is the reference for the legal measure of fiber grains, meals, flours, and feeds, even if it accounts for most of the cellulose but only a portion of the lignin and no ash, so it underestimates true fiber and is less than acid detergent fiber (ADF).

2. VAN SOEST (ACID DETERGENT FIBER)

This method is based on the concept that plant cell substances can be divided into less digestible cell walls (made of hemicellulose, cellulose, and lignin) and highly digestible cell contents (containing starch and sugars). These two components can be separated by using a neutral detergent and an acid detergent solution:

> Neutral Detergent Fiber (NDF)
The sample is digested in the Neutral Detergent Solution to separate the neutral detergent soluble fraction from the neutral detergent-insoluble fraction. The remaining dry matter is estimated and the proportion gives the neutral detergent fiber (NDF).

> Acid Detergent Fiber (AFD)
The Acid Detergent Solution (ADS) solubilizes the hemicellulose while lignin and cellulose remain insoluble. The residue is weighed for the determination of ADF. It includes cellulose and lignin.

> Acid Detergent Lignin (AFL)
The remaining residue from the ADF analysis is solubilized by 72% sulfuric acid, leaving the lignin (ADL) which is determined gravimetrically.

Eliminate the risk of errors and ensure consistent results with the crucible technology

Even if fiber is defined by the method used to isolate it, here are some technical standards to observe to achieve reliability and efficiency.

The crucible technology is fully adherent to official standards (ISO and AOAC). Fiber residues stay in crucibles during all steps of the analysis, eliminating the risk of errors and ensuring consistent results.

In addition, crucible technology features other advantages, such as:

No risk of sample contamination, as each sample is placed in its own crucible
High accuracy of results, as each crucible, can accept up to 3 g of sample. This is very important when the sample is not homogeneous
Low cost per analysis and long service life of consumables, as each crucible can be used for up to 20 analyses

A complete offer of advanced instrument and glass crucible to fulfill all your fiber determination challenges

According to the official crucible technology, VELP provides a complete set of different glass crucibles, depending on the type of sample to be analyzed, made to perfectly fit:

FIWE Advance: the fully automatic fiber analyzer for crude and detergent fiber determination, requiring 2-min operator time with a unique user interface and cloud connectivity
FIWE: the semi-automatic fiber analyzers that use pre-heated reagents for reliable fiber analysis results
COEX: the cold extractor that performs rapid fat extraction on feed samples, directly in the FIWE Advance and FIWE glass crucibles

Discover the complete range of VELP Glass Crucibles >

Would you like to learn more about the benefits of the different VELP solutions for fiber determination in the feed?

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