Tackling the presence of beta-mannans in feed could unlock sizeable gains for industry
Over the last few decades, some of the most important improvements in animal nutrition have come from better understanding—and then dealing with—the anti-nutritional factors in widely-used feed ingredients. As enzymes such as phytase and xylanase have come into near universal use, they have unlocked significant gains in animal health and performance.
Now, Elanco would like to see the same level of attention extended to another antinutritional factors (ANF): β-mannans. Citing years’ worth of research into the harm these can cause by triggering the defence mechanisms of the innate immune system that cause intestinal inflammation. Elanco argues that β-mannans are leading to a loss of metabolisable energy of up to 90 kcal/kg, reduced flock uniformity, and higher susceptibility to infections.
“During periods of increased stress, during an acute infection, for example, the β-mannans’ adverse effects increase dramatically, and the productivity loss can even exceed 20%,” claims Karl Poulsen, regional nutritional adviser at Elanco. “When this happens, the β-mannans’ influence on health becomes much stronger, with increased mortality and morbidity.” The problem, of course, is that β-mannans are common polysaccharides in plant-based ingredients. To help understand just how widespread β-mannans are in animal feed, Elanco has undertaken a survey to update the reference tables used to determine whether the application of a β-mannanase to break down these ANF would be appropriate. In the interview below, Poulsen discusses this work and makes the case for the industry taking the problem of β-mannans more seriously.
What kinds of ingredients tend to have β-mannans? How do they differ from other ANF such as trypsin inhibitor?
β-mannans are found in most vegetable feed ingredients. They are non-starch polysaccharide (NSP) fibres that belong to the hemicellulose fraction of plants. The soluble β-mannan content in different ingredients varies from negligible to over 5%. The β-mannan content is relatively high in many protein meals — around 0,6% in soya and sunflower meals, and up to about 7% in guar and palm kernel meals — so they are typically important contributors to the dietary β-mannan content.
β-mannans are different from other ANF because the damage they cause is mainly created by protective measures the innate immune system takes to fight the β-mannans. Simply put, the immune system mistakes even very low levels of β-mannans for invading pathogens (pathogen-associated molecular pattern), and then starts defending against a problem that does not exist. This indirect activity makes β-mannans different from most ANF, which have a direct influence on animal performance or efficiency. Trypsin inhibitors that reduce the activity of trypsin are a good example of an ANF with a direct influence. Another difference is that trypsin inhibitors are inactivated by thermal processing, while β-mannans can withstand thermal procedures used in modern feed production, such as drying, pelleting, and extrusion.
Why did Elanco decide that a survey of β-mannan content in different feed ingredients was necessary?
Elanco recently completed a global survey of the β-mannans content in commonly used feed ingredients. The survey includes 236 samples of common feed ingredients from 21 countries across the globe. This makes it the largest β-mannan survey, so far. An important motivation behind this survey was to update our reference table for β-mannan content in common feed ingredients. This table is important because our recommendation to use Hemicell™ is based on the estimated dietary β-mannan content, and the values are included in a convenient mannan-calculator that makes it easy to estimate the dietary β-mannan content and predict if the addition of a β-mannanase will be cost effective.
What are the most striking findings from the worldwide β-mannan survey? What did the survey conclude?
The main outcome of the survey was new information about the soluble β-mannan content in 36 common feed ingredients. The results did not indicate a correlation between the contents of crude protein or crude fibre and β-mannans, so the β-mannan content in dehulled soybean meal with higher crude protein content is not reduced, and it is not increased in dehulled soybean meal with higher fibre content.