The role of dietary fibre in animal nutrition and intestinal health
PROF. KNUD ERIK BACH KNUDSEN, AARHUS UNIVERSITY, DENMARK
Even though it is not digested, dietary fibre plays a key role in the nutrition of non-ruminant production animals, not only because of its functional properties, but also through its ability to help balance the microbiota that reside in the gut. Professor Knudsen reminds us of the importance of this portion of the ration in promoting optimum performance through improved gut health.
Dietary fibre represents the fraction of carbohydrates, along with the non-carbohydrate polyphenolic ether lignin, that is not digested by endogenous enzymes in the small intestine of non-ruminant species. According to recent definition, dietary fibre consists of non-digestible oligosaccharides, resistant starch, non-starch polysaccharides and lignin.
In addition to being non-digestible by endogenous enzymes, dietary fibre possesses several functional properties in the different parts of the gastrointestinal tract.
- Soluble dietary fibre influences gastric emptying, and digestion and absorption of nutrients in the small intestine
- Dietary fibre influences the rate, extent and type of products formed during fermentation in the large intestine
- Dietary fibre also influences the rate of passage in the small and large intestine
All in all, dietary fibre influences key parameters that are of importance in the nutrition of animals, but additionally, it may influence gastrointestinal health. The microbiota that resides in the gut encompasses hundreds of different microbial species. The diversity and the activity of the microbiota are influenced to a large extent by dietary composition, particularly the content and composition of the dietary fibre portion, and by the genotype of the host.
The outcome of the anaerobic fermentation of feed residues is the production of short-chain fatty acids, gases, urea and microbial growth along with an array of small organic molecules that not only have significant impact on the gut itself, but also on other organs through absorption. Small molecules originating from the diet, the host and from the microbes are also likely to have important functions in keeping the relationship between hosts and the microbiota of their commensal in balance.
A “healthy gut”, although not well defined, is an important prerequisite to reduce production losses and reduce the use of antibiotics administered due to disturbances of the gastrointestinal functions, for example disturbances caused by pathogens resulting in diarrhoea.