Xylanases and Debranching Enzymes - Unlocking Fiber

One of the most frequently asked questions: Is there a way to enhance the digestibility and availability of nutrients within my animal feeds, regardless of ingredient and nutrient composition? In recent years, enzyme solutions have been introduced into the marketplace that are capable of improving the digestibility and availability of vital nutrients from feed - such as energy, amino acids, phosphorus, and calcium - resulting in better animal performance and higher profitability. It is important to understand that feed-grade enzymes differ by supplier, that every enzyme has a specific substrate that they work on, and that not all enzymes are created equally. Today, the marketplace has placed a lot of emphasis on xylanase because xylanase can degrade fiber; however, a single xylanase is simply not enough. To effectively break down the complex structure of fiber and nutrient-fiber interactions found in plant-based ingredients, in-feed enzymatic solutions need to contain the synergistic activities between arabinofuranosidases (ABFs; sugar debranching enzymes) and xylanases (xylan-cleaving enzymes).

We often speak of non-starch polysaccharides (NSPs) and fiber interchangeably because both are indigestible and very complex in terms of structure. Fiber is Mother Nature's way of encasing and protecting nutrients in the seed so that the seed has food for when it germinates and grows into a plant. Based on the type and amount of sugars, in addition to the chemical bonding between the sugars, fiber/ NSP content can differ from one plant-based ingredient to another. Arabinoxylan (AX) is a very large and important component of fiber that is found in all cereal grains. It is primarily composed of long polymer chains of indigestible b 1-4 linked xylose sugars, to which arabinose and other sugars bind and become branch points. This AX complex effectively binds to, interacts with, and holds other fiber components together, essentially forming an impenetrable cage-like structure. To effectively break apart AX, ABFs are used to first cleave side sugars off the xylan backbone. Clearing away these side sugars creates an open space along the xylan backbone that enables various xylanases to efficiently access, bind, and break apart the xylan backbone of the fiber chain. By "unzipping" and degrading this component of fiber, other fiber components and interactions are destabilized, resulting in higher nutrient digestion and availability.

Whether tested at the university level or implemented in the field at commercial farms, supplemental ABFs and xylanases work in synergy across a wide array of feed types to ensure consistent breakdown of NSPs and improvement in both the digestion and retention of starch, protein, fat, and minerals. In trials where ABFs and xylanases were added, diets formulated with 3% less apparent metabolizable energy and digestible essential amino acids maintained body weight gain and feed conversion. Results depend on the diet, enzyme dose and production conditions.

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