NUTRITION ▶▶▶


Deciphering the dietary fibre message


Dietary fibre is complex; this message is short, but clear to animal nutritionists. The key to unravelling this complexity is interpreting the analytical data and the biological response that fibrous ingredients will elicit.


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BY DR NEIL JAWORSKI, DR TREVOR FABER, TROUW NUTRITION; AND DR FRED MADSEN, MADSEN NUTRITION SERVICES


ietary fibres can be viewed as beneficial or detri- mental based on the context of the total diet. When dietary fibres are poorly fermented, they still promote laxation, epithelial cell regeneration


and favourable stool quality. When dietary fibres are rapidly fermented, they provide nourishment for intestinal bacteria, which in turn produce beneficial metabolites that promote animal health. In contrast, excessive fermentable dietary fibre can result in osmotic imbalances and other intestinal disorders. What are some of the new ways of viewing and characteris- ing fibre, and how can they help us construct improved diets?


Capturing dietary fibre Crude fibre measurement was developed in the 1860s to esti- mate the indigestible fractions of a feedstuff. This method is, as the name suggests, crude, and has been found to provide very little useful information in modern diet formulation for sim- ple-stomached animals. Unfortunately, this methodology and label guarantee is still used. Numerous other methodologies are also available, with detergent methods and total dietary fibre methods being the most prevalent. The detergent methods in- clude neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) (see Figure 1). These methodol- ogies allow the identification of the insoluble hemicellulose, cellulose and lignin, respectively, within an ingredient. The total dietary fibre (TDF) methodology accounts for a broader array of fibre types that can be partitioned into insolu- ble dietary fibre (IDF) and soluble dietary fibre (SDF). In combi- nation with detergent analyses, this methodology allows an understanding of the chemical composition and functionality of a dietary fibre source. These values, however, do not explain the physiological effects or the complexity of the fibre sub- strate, since sources of dietary fibre are heterogeneous and their chemical composition does not tell the whole story.


Figure 1 - The detergent methods include neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL).


FOS, GOS, XOS, AXOS, Raffinose, Stachyose, Verbascose


B-glucan, Pectins, Galactomannans, Guar gums, Fructans


RS1, RS2, RS3


Arabinogalactans, Arabinoxylan, Glucuronoxylans, Xyloglucans Galactomannans


Crude fiber ADF NDF iDF Fast Fermentable >>>>>>>>>>>>>>>>> Slowly Fermentable >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Resistant


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▶PIG PROGRESS | Volume 36, No. 2, 2020


PHOTO: RONALD HISSINK


Non-Digestible Oligosaccharides


Soluble Hemicellulose


Resistant Starch


Insoluble Hemicellulose


Cellulose


Lignin


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