Dietary fibre (DF) is an accurate term to define in practice the fibre fraction of ingredients and diets and includes cell walls, stored non-starch polysaccharides and lignin. Fibre has been associated traditionally with reduced palatability and impaired nutrient utilisation in non-ruminant diets. However, DF has also an important role in animal feeding, and a minimum amount of fibre is required to maintain the physiological functions of the gastrointestinal tract (GIT). The impact of DF on GIT physiology and animal behaviour depends on the species, age, management and health status of the animal. In addition, the response differs considerably with the physico-chemical characteristics of the fibre source used. Solubility, degree of lignification, size, density and water holding capacity, are key factors affecting the benefits (or negative effects) of DF on performance of non-ruminant animals. In general, insoluble fibre sources such as oat hulls and other cereal co-products, are better adapted than soluble fibre sources such as sugar beet pulp to the physiology and function of the GIT of poultry. Soluble fibres increase the viscosity of the digesta which reduces feed intake and limit the contact between nutrients and endogenous enzymes in the lumen of the GIT. As a consequence, soluble fibres should be avoided in poultry feeding. In pigs, however, both types of fibre might be of benefit depending on age and health status of the animal (i.e., inclusion of sugar beet pulp in diets for gestating sows and oat hulls in diets for young weaned pigs). Currently, most nutritionists formulate diets for pigs and poultry based on crude fibre values, accepting that all fibre sources are “equivalent” in nutritional value and physiological effects on the GIT of the animals, which in most cases is not correct. Because of the complexity of the response, it is difficult to predict and give an accurate recommendation on the type and level of fibre to use in commercial diets for pigs and poultry.
Presented at the International Fibre Summit 2019 (https://internationalfibre.com/). Reproduced with permission from the organizers.