What it is about the chemistry of β-Mannans that makes them such a problem?

β-mannans are high molecular weight molecules formed of a long chain of mannose sugar units with galactose side chains. β-Mannans are unable to be naturally broken down in the bird or pig’s digestive system.1


It is the long mannose structures, found in the backbone of β-mannans, that are also found in many pathogens, and that the animal’s innate immune system responds to.1,2


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Are there different types of β-Mannan and are some more problematic than others?

Yes - soluble β-mannans (often referred to as β-galactomannans) are the most important type because they are much more likely to come in contact with immune receptors and provoke an innate response.2,3,4


What feedstuffs contain β-mannans and how much do they contain?

Most vegetable feed ingredients contain β-mannans:5,6

Ingredients β-Mannans, Pct., as is1 Minimum Maximum
Corn gluten meal 0.17 0.10 0.24
DDGS 0.57 0.23 1.09
Oats 0.31 - -
Oats, dehulled 0.16 0.09 0.22
Palm kernel meal 7.24 5.34 10.90
Peas 0.11 0.09 0.12
Rapeseed meal 0.18 0.13 0.37
Rapeseed expeller 0.13 - -
Rapeseed, whole 0.08 0.07 0.09
Soya hulls 6.67 6.43 6.91
Soyabean meal 44% CP 0.79 0.38 1.30
Soyabean meal 48% CP 0.59 0.28 1.00
Soyabean meal, fermented 0.59 0.58 0.59
Soyabean meal, full fat 0.71 0.42 1.05
Sunflower meal, <=32% CP, w/ hulls 0.62 0.53 0.69
Sunflower meal, >32% CP, w/o hulls 0.57 0.42 0.75
Wheat 0.27 0.11 0.42
Wheat bran 0.25 0.21 0.34
1 Estimated Soluble β-Mannan, % = Soluble mannose % x 1.5

Does the effect of soluble β-mannans depend on the source?

The source of the soluble β-mannans is unlikely to affect their influence on the likelihood or magnitude of the animal’s immune response or its effect on their performance because it is the mannose sugar molecules that are recognized by the innate immune system.2,3,4