The largest quantities of fibre in most commercial diets for pigs originate from cereal grains and cereal grain co-products. The quantitatively most important fibre components in such diets are arabinoxylans and cellulose, which are poorly digested by endogenous and microbial enzymes in pigs. To increase fermentability of these components it is, therefore, necessary to add exogenous enzymes to the diets. Theoretically, four enzymes are needed to hydrolyse cellulose, whereas nine enzymes are needed to hydrolyse arabinoxylans. The greatest energy value of fermented cellulose will be obtained if cellulose can be fermented in the small intestine, but to achieve that, all four cellulose degrading enzymes need to be added to the diets. However, for arabinoxylans, the objective is not to achieve complete hydrolysis in the small intestine because absorbed pentoses do not contribute to the energy status of the pig. Instead, the objective is to hydrolyse arabinoxylans in the hindgut of pigs and microbial fermentation in the hindgut may be aided by addition of at least four enzymes to the diets. There are, however, only few studies with documented effects of addition of multiple enzymes to diets for pigs and more research in this area is needed.
Presented at the International Fibre Summit 2019 (https://internationalfibre.com/). Reproduced with permission from the organizers.