Practical application of matrix values for enzymes

One practical and economical strategy to cope with this is the proper use of enzymes and precise implementation and utilisation of their matrix values.

Identifying the proper combination of enzymes depends on factors such as dietary ingredients, the age and physiological status of the animals and the feeding strategy of the operations. Phytase is one of the most commonly used enzymes in the animal industry, along with a combination of polysaccharide (NSP) degrading enzymes. Matrix values are categorised in three segments or parts: minerals (P, Ca, and Na), energy (Kcal ME, MEn, or NE), and amino acids.

To take advantage of the full value and maximise the economic benefits of enzymes a detailed understanding of the highly influential impact of matrix values including all three segments is essential. Most of these savings are attributed to improved energy contribution and reduced ingredient costs. In practice, regarding phytase, a significant number of operations focus and utilise the mineral fraction of total matrix values and avoid using the energy and amino acid fractions. Most of the economic value of phytase enzymes, at optimal dose levels of the proper phytase, is in the energy fraction (about 50% of total savings) and amino acids (about 25- 30%). By avoiding use of these portions, most of the potential economic savings remain unexploited.

Downspec values

The maximum benefit is achieved when all three portions of matrix values are implemented as “downspec values from the base diet.” It is most practical to consider the matrix values of phytase first and adjust the values of NSP enzyme to be added to the base line matrices of the phytase enzyme used. For this, it is imperative to use an efficacious phytase with proven matrix values for different conditions, diets, phytate levels and available calcium levels. In addition, it is important to be aware of the methodologies used for determining matrix values and the number of studies/datasets used to derive the matrix value. A recent publication (Dersjant-Li) reported a modelling result for 13 datasets to determine the digestible AA matrix for a new phytase.

Several factors must be considered when determining the optimal dose of enzymes and most specifically phytase levels in the diet. The choice of a proper phytase in a proper dose is the first step. The next move is to match the NSP degrading enzyme, in a proper dose with the phytase based on the operational targets or KPIs. Several distinct factors affect the performance of phytases and these should be considered to maximise results. One of the most critical points is the optimal range of phytase activity. Current commercial phytases vary significantly in their efficacy at pH levels close to those in the upper gastrointestinal tract (GIT). This is an important difference, given that the goal is to eliminate the detrimental effects of phytate and its associated anti-nutritive properties as early as possible. 

The level of phytate (analysed vs. calculated) is a key factor and the basis for evaluating the proper dose levels and calculations for matrix values. The others are levels of TAX (total arabinoxylans), soluble and insoluble fractions, undigested protein fraction, and analysing calcium in terms of total dietary content and solubility, and ratio to phosphate. The final calculations also need to be matched with the nutritional strategy of each operation. The matrix value for a single enzyme and for the combined enzymes should be based on these substrate levels. Field experience and research studies prove that a practical verified approach to reduce feed costs and maximise the benefits of enzymes, when full matrix values are implemented, is low-protein diets (diluted amino acid levels) and the use of alternative ingredients.

Application evaluated

One such study was presented at ESPN (Bello), where different matrix value application approaches were evaluated; mineral matrix only, minerals + energy or full matrix (minerals + energy + digestible AA). The diets were maize-SBM-RSM-based. The dietary treatments were 1) a nutrient and energy adequate positive control (PC); 2) PC reduced in available P by 0.22 % point (p),  Ca by 0.23% p, and  Na by 0.05% p at each of the four phases (NC1, mineral matrix only); 3) NC1 reduced in ME by 72 – 51 kcal/kg across the four phases (NC2, mineral plus energy); 4) NC2 reduced in digestible AA by up to 0.06% p across the four phases (NC3, full matrix) and diets 5); 6); and 7) were the NC1, NC2, and NC3 respectively supplemented with Axtra PHY GOLD at 1250 FTU/kg. Axtra PHY GOLD maintained performance vs PC. As shown in  2 the application of full matrix resulted in the greatest cost benefit. 

Another study evaluated the application of Axtra PHY GOLD alone or with Axtra XAP, a xylanase-amylase-protease enzyme blend, on growth performance, bone quality, economic benefit and carbon footprint (Bello).  The diets were based on maize, wheat, SBM, sunflower meal and canola meal.

The diets were:

• a nutrient and energy adequate positive control (PC);
• a diet reduced in Ca by 0.24 – 0.21% point (p), digestible P by 0.20 – 0.18% p, Na by 0.05% p, dig AA by up to 0.06 – 0.04% p and ME by 79 – 44 kcal/kg vs PC across the 3 phases (NC1);
• NC1 supplemented with Axtra PHY GOLD at 2,000, 1,500, and 1,000 FTU/kg (NC1+PhyG) in starter, grower and finisher phase, respectively; and
• the NC1+ Axtra PHY GOLD with additional reduction in dig AA by up to 0.02% p and ME by 75 kcal/kg and supplemented with Axtra XAP  (xylanase at 2,000 XU/kg, amylase at 200 U/kg and protease at 4,000 U/kg) in all dietary phases (NC2+PhyG+XAP).

Both NC1+ Axtra PHY GOLD and NC2+ Axtra PHY GOLD +Axtra XAP maintained performance and bone quality vs PC (Table 1). The overall feed cost, USD/kg BWG and total carbon footprint, g CO2 eq/kg BWG were decreased by NC1+ Axtra PHY GOLD and further decreased by NC2+ Axtra PHY GOLD +Axtra XAP vs PC (P<0.05) (Figure 3).

Clearly, application of the full matrix for phytase alone or in combination with other mixed enzymes can reduce the feed cost, lead to production benefits and contribute to sustainable broiler production. Therefore it is important to use the right enzyme mixture, at proper dose levels, and implement the full matrix values. Here, the real difference becomes clear in terms of the efficacy of the enzymes in practice and the full value can be realised.