DF is generally considered as a fraction with a low energy content. This diluting effect of the diet is used to increase the feed intake during low performance of animals. DF influences transit time with a reduction in the upper and increase in the lower digestive tract and, therefore, decreases the digestibility of almost all nutrients and energy. On the other hand, it increases the microbial growth in the gastrointestinal tract. This can lead to an increased excretion of nutrients in faeces. Finally, DF beneficially influences well-being and health. Fibrous feedstuffs give pigs the opportunity to chew the feed over a longer time. More short chain fatty acids are produced and eventually undesired micro-organisms are excluded. A regular peristaltic action avoids the possibility of constipation.