Studies proved that β-mannan and its derivatives polysaccharide bodies which have a strong ability to block nutrients absorption. β-mannan, especially water-soluble β-mannan, has great anti-nutrition affect. Even if there is a little amount of β-mannan in feed materials, it will cause a very bad effect in blocking absorption of nutrients for livestock and poultry (mainly for monogastric animals). It may result in the trophism diarrhea and reduce animal growth, as well as nutrients utilization, reduce the egg weight and laying rate thus affects the economic benefit of the raisers.

β-mannan, can increase the viscosity of the digesta, affect digestion and absorption of nutrients thus it may result in the intestinal clostridial infection; it can affect the secretion of insulin and the insulin-like factor IGF-1 as well, so it can reduce animal performance; it can absorb water that is 7 times of its own weight as well as absorb many varieties of trace elements to reduce their bioavailability. Since there is no mannanase in the endogenous digestive enzymes of livestock and poultry, the addition of exogenous mannanase to degrade mannan is necessary.

β-mannan is the major component of anti-nutritional factor of NSP, its anti-nutrition effect can be summarized as the following two aspects:

1. Reduce the digestion and absorption of nutrients, affect diet conversion rate and animal performance.

2. Interaction with microorganism system in the back-end alimentary canal thus result in anaerobic fermentation and produce a large amount of clostridium which will produce mycotoxin and inhibit animal growth.