Chapter 10 Beta-glucans and beta-glucanase in animal nutrition, do we understand their full effects?

Feeding barley to poultry and pigs has long been known to be affected by beta-glucan found in grain cell walls. For poultry, the beta-glucan effect can be negative because of high viscosity found in the digestive tract reducing nutrient digestibility and destabilising the resident microbiota. The effect in pigs is less because of lower digesta viscosity and an increased ability of small intestine bacteria to depolymerize beta-glucan. Despite differences in the extent of the beta-glucan effect, the use of exogenous beta-glucanase effectively reduces or eliminates the negative effects and stabilizes the digestive tract microbiota. Despite this fundamental knowledge, research using humans, as well as in vitro models and other animal species, suggests that poultry and pigs might benefit from a more detailed understanding of beta-glucan effects. Two areas with promise, particularly in a reduced or antibiotic free era, are positive effects of beta-glucan on host immunity and the potential for beta-glucan to serve as a prebiotic in animal feeds. Superimposed on this knowledge is the need to understand how exogenous beta-glucanase can be used to produce hydrolysis products that optimize these areas.