Adaptation of the Microbiome towards Fibre Digestion: Effects of Age and Dietary Ingredients

The dietary fibre fraction of European wheat-based poultry diets largely consists of non-starch polysaccharides (NSP), mainly arabinoxylans (AX). As poultry lack the metabolic capacity to produce carbohydrate active enzymes in order to degrade the NSP of cereal cell walls, they rely on their intestinal microbiome to hydrolyse and ferment the dietary fibre fraction of the feed. However, the colonisation by and composition of the gastrointestinal microbiota is strongly influenced by different host-specific and diet-related factors, which hence impact and modify dietary fibre digestion. In recent research, the importance of broiler age and the age-related microbial development on the capacity of broilers to degrade wheat AX was demonstrated. The first colonising microbiota were able to hydrolyse the dietary AX polymers, but not yet into fermentable compounds. However, as the broiler aged, adaptation of the microbial fibre degrading and fermentation capacity towards the AX substrates entering the hindgut was observed, which finally resulted in an increased fibre digestion with broiler age. Furthermore, to overcome the anti-nutritional effects of the dietary NSP substrates, endoxylanases are frequently added to the broiler’s diet. Addition of these enzymes clearly improves fibre digestion, due to the modification of both the structural and physicochemical characteristics of the NSP substrates, thereby making them more available for microbial fermentation. Supplementation with 0.50% arabinoxylan-oligosaccharides (AXOS), in essence prehydrolysed AX, revealed that the fibre solubilizing and fermentation capacity of the intestinal microbiota can be kick started at young broiler ages. It is recommended that nutritional intervention strategies take into account the age-related and diet-adapted fibre degrading potential of the intestinal microbiota. Depending on dietary ingredients and broiler age, microbiota will contribute differently to fibre digestion.

Presented at the International Fibre Summit 2019 (https://internationalfibre.com/). Reproduced with permission from the organizers.