Enzymes are natural proteins! They are secreted by all animalsas part of the process of feed digestion. The stomach, small in-testine, and pancreas all secretea wide range of enzymes to digestcarbohydrates (major source ofenergy), lipids (also a goodsource of energy), proteins(amino acids), and mineral com-plexes. Enzymes literally chopdown large compounds (such asstarch, for example) into smallerpieces (such as maltose and dex-trin) and eventually into compo-nent building blocks or units (inthe case of starch, being glu-cose – a simple sugar). Thesesimple compounds are then ab-sorbed to be used by the animalfor maintenance and productionpurposes.Without the digestion process provided by enzymes virtually no nutrient can be absorbed.To work, enzymes need two condi-tions. First, they need the suitablesubstrate. Thus, a protease can-not break down a carbohydrate,nor a phytase can work on a pro-tein. So, there must be a matchbetween each enzyme and itssubstrate. The enzyme recognizesand attaches itself on the sub-strate in a mechanism that resem-bles the likeness of akey-and-lock analogy. Second,they need the proper environmentin terms of acidity or alkalinity.For example, enzymes secreted inthe stomach work best under lowpH (acidic) as this is the naturalenvironment of the stomach. Incontrast, enzymes secreted in thesmall intestine work best in ahigher pH environment, for thesame reason.Enzymes secreted by the animalare called endogenous. Thoseadded in the animal’s feed arecalled exogenous. Commercial enzymes (exogenous) are used toenhance the natural process of digestion. Examples include amy-lase (starch) and protease (pro-tein). Other enzymes are used toprovide for the digestion of sub-strates that are not digested bythe animal. This includes phytase(phytate phosphorus) and xylanase-glucanase (fiber compo-

nents). The majority of the com-mercial enzymes have been thatof the latter form, although amy-lases and proteases are beingused with increasing frequencyand success.Exogenous enzymes are also natural proteins, produced bycontrolled microbial fermentation,and they work under the sameprinciples as endogenous enzymes. Like their endogenouscounterparts, they too require theproper substrate and correct pHconditions to exert their full effect. In addition, there are a fewother requirements for exogenousenzymes: they must be stableunder diverse feed processingand storage conditions, they mustbe safe for human operators, andof course, their use must improveprofitability for the animal pro-ducer!Today, we can easily expect a 10%improvement in phosphorus digestibility by a modern phytase.Likewise, a glucanase or xylanaseenzyme can improve metaboliz-able energy in feed by about 50kcal/kg, or even more (up to 150kcal/kg is not unreasonable forlow quality cereals). Finally, a protease improves protein digestibility around 2-5% depend-ing on the type of ingredientsused. In the animal industrywhere profit margins are thin,such improvements as those con-ferred by exogenous enzymes areindeed substantial.In conclusion, enzymes are natu-ral, safe, and important for theanimal. Supplementation in feedenhances the process of diges-tion, and reduces the amount offeed being excreted. This, in turn,improves animal performance,profitability, and reduces environ-mental pollution.

Dr. Jon WilsonGlobal Innovation Project Manager

Feed Enzymes, DSMJonathan-W.Wilson@dsm.com

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What are Enzymes andHow do they Work?