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The Additivity Factor: How enzymes can boost the digestibility of amino acids


The formulation of diets that are nutritionally adequate and at the same time economical is a key factor in reducing costs and increasing margins for animal producers. 

Feed enzymes offer a range of useful options for enhancing the digestibility of the diet. The individual capacity of phytase, carbohydrase and protease to increase the digestibility of amino acids has been extensively demonstrated. However, it is increasingly the case that diets are formulated with more than one enzyme and so the additivity of enzyme effects has become a focal area of ongoing research.

In a collaboration between DSM Nutritional Products, Switzerland and Massey University, New Zealand,  the effect of phytase (DSM HiPhos), protease (DSM ProAct) and a mixture of phytase and protease on ileal amino acid digestibility in broilers was explored using three substrates: corn, soybean meal (SBM), and a mixture of corn and SBM.  The effect of phytase on amino acid digestibility was positive across all three substrates, but significant only for cysteine. The positive effect of protease was statistically confirmed for all amino acids. However, combining protease and phytase in the diet delivered substantial synergistic effects on several essential amino acids such as lysine. 


Figure 1: Standardized ileal digestibility (SID) of lysine in corn, SBM and a mixture of corn and SBM without enzyme addition or with phytase and protease alone or combined (redrawn from Cowieson et al., 2020).

It is possible that protease increases access for exogenous phytase to phytate. It is also plausible that the two enzymes enhance amino acid transport function, or that the increases in myo-inositol yield with phytase encourages protein accretion and amino acid absorption. These two feed enzymes used together thus have considerable potential for improving competitiveness of the feed industry. 

Currently celebrating two decades of innovative collaboration, the DSM|Novozymes Feed Enzymes Alliance offers the world’s most innovative and complete portfolio of feed and gut health enzymes and is continually working to develop next-generation enzymes that will take animal production to even higher levels of performance and sustainability. The Alliance produces phytase (DSM HiPhos) and protease (DSM ProAct) feed enzymes, along with a broad variety of carbohydrases.


1A.J.Cowieson, J.O.B.Sorbara, G.Pappenberge, M.R.Abdollah, V.Ravindran. Toward standardized amino acid matrices for exogenous phytase and protease in corn–soybean meal–based diets for broilers. Poultry Science. Available online 25 March 2020.


November 13 2020

The Additivity Factor: How enzymes can boost the digestibility of amino acids