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Enzyme Solutions for Poultry Diets

Characteristics of Effective Enzyme Solutions for Poultry Diets

Published: August 24, 2012
By: Gwendolyn Jones (Danisco Animal Nutrition)
Enzymes are widely accepted to improve the utilization of nutrients in poultry diets and increase the capacity of birds to perform on less digestible feed ingredients. However, increasing volatility in raw material prices for feed ingredients and stricter regulations on feed safety to control salmonella in poultry production, are changing the way we formulate and process poultry diets and requires more sophisticated enzyme technologies to maximize the efficacy of enzyme solutions. 
Matching dietary substrate levels
Both wheat and corn are highly variable in the amount of energy, which the bird is able to metabolise and the majority of phosphorus is present as phytate, a substance which is unavailable to the bird. The most common feed enzyme used in poultry diets is phytase, which releases phosphorus bound to phytate in grains. This can help to reduce the dependence on supplementary inorganic phosphorus. Furthermore E.coli phytases have also been shown to be highly effective against the antinutrient effect of phytate and thus also help to increase the availability of dietary energy and protein in the bird. There is increasing independent evidence to show that both carbohydrase and protease enzymes can offer an advantage on top of phytase in poultry diets.  This is because these enzymes are able to release extra energy from the starch in corn.  Around 65-70% of the energy in corn is derived from starch, however not all of it comes in an easily digestible form and digestibility has been shown to be highly variable between batches of corn.  For wheat, on the other hand, energy digestibility generally depends on viscosity, which is caused by the presence of soluble fibres in the grain – this too varies from year to year.
Specific enzymes can be used to target the substrates which are reducing the availability of energy in diets and thereby significantly increase the digestibility of dietary energy. For corn-based diets the most relevant enzyme activities have been shown to be xylanase, amylase and protease   Xylanase breaks down cell walls to expose starch for digestion. Protease helps to release the starch encapsulated by, and bound to, storage proteins. Amylase, a starch-digesting enzyme, can be added to the diet to help the bird digest starch. Xylanase also reduces the viscosity of wheat, which in turn reduces variability in the availability of energy to the bird in wheat based diets. Wheat viscosity is linked to the presence of non-starch polysaccharides (NSPs) such as arabinoxylans, which xylanase degrades.
As higher levels of cheaper alternative raw materials, such as corn DDGS, barley, wheat and rape seed meal are used in poultry diets the levels of potentially problematic substrates will increase. For example, the level of arabinoxylans in a corn-soy based poultry diet will increase by approximately 25% in response to including 10% DDGS into the diet. Therefore the nutritionist needs to be aware of these substrates and how much their levels are changing in response to raw material usage in order to determine appropriate enzyme additions.  Danisco Animal Nutrition is a pioneer in feed enzyme technology and analyzes over 1000 grain samples a year to assess changes and variability in substrate levels for enzymes in poultry diets.  Optimizing the combination of xylanase, amylase and protease to match the relevant substrate levels in modern, more complex poultry diets including corn DDGS has led to increased flexibility in formulating cheaper diets without negative impact on performance of birds in the US (Figure 1). More recently a xylanase and beta-glucanase combination developed by Danisco Animal Nutrition was approved for the use in EU poultry diets to match the substrate levels of mixed grain diets including wheat and barley and increase the consistency of performance in birds fed these diets.  
Figure 1. Performance and digestibility benefits from the addition of a combination of xylanase, amylase and protease enzymes (Axtra XAP) to complex diets based on corn and containing DDGS. Phytase at 500 FTU/kg feed in all diets.
Characteristics of Effective Enzyme Solutions for Poultry Diets - Image 1
Enabling more effective salmonella control
Concerns over food safety and feed hygiene have resulted in feed mills often using pelleting temperatures of 90- 95°C. Processing poultry feed ingredients at high temperatures not only risks destroying heat sensitive nutrients and feed additives but also  leads to increased starch gelatinisation and fibre solubilisation. This causes an increase in viscosity of the digesta, leading to poorer nutrient absorption and sticky droppings (Table 1). Furthermore trials showed significant decreases in body weight gain by up to 7% and a poorer feed conversion ratio (4.4%) in broilers.
The viscosity in wheat is linked to the significant amounts of non-starch polysaccharides (NSPs) such as arabinoxylans present in wheat. Soluble arabinoxylans increase the viscosity of the digesta in the small intestine, which reduces the digestion and absorption of nutrients and thereby reduces the availability of energy to the bird. Xylanase is an enzyme which will degrade arabinoxylans and therefore offers the means of reducing viscosity in wheat based diets and hence reduce the variability in the utilisation of energy by the bird. The incidence of sticky droppings will also be reduced by xylanase addition. The issue of feed enzyme stability during conditioning and pelleting therefore becomes highly relevant, when trying to meet feed hygiene requirements.
Table 1. Properties of gut contents in broilers fed pelleted diets based on 77% wheat, either non-heat-treated or pelleted at 90ºC.
Characteristics of Effective Enzyme Solutions for Poultry Diets - Image 2
Advanced enzyme solutions can stand the heat
As the pelleting temperatures of poultry diets increase more sophisticated technologies are required to protect enzymes from the heat, to ensure their bioefficacy in the animal. Thermo Protection Technology (TPT), a patented coating technology developed by Danisco Animal Nutrition, has been found to be highly effective in protecting their second generation E.Coli phytase from heat. This coating technology enabled a recovery rate of 96% after exposure to feed pelleting temperatures of up to 95ºC, under very precisely controlled processing conditions. Trials have also proven a fast release of phytase activity from Phyzyme XP TPT in the gut, with a bioefficacy equivalent to the uncoated product in mash diets.  Danisco Xylanase, is an inherently more heat stable xylanase and does not require coating to remain stable at pelleting temperatures of up to 90ºC. 
Conclusion
In order to meet the demands of increasingly more complex poultry diets and safer feed, effective enzyme solutions require the right combination of activities to specifically match the relevant substrates in the diet and achieve high tolerance to heat. The use of enzyme solutions should ideally be combined with software tools to determine the optimum dosage to maximize cost effectiveness in the diet. 
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kamaran abduljalil abbas
Salahaddin University
29 de abril de 2020

The matrix value of individual or multi enzymes when given by the enzyme producer can be depended when the producer company is well trusted.

Andres Felipe Belalcazar
6 de febrero de 2020

Hello all, I always argue that enzymes are not energy providers in animal feed. To use the famous "matrix values" of the enzyme products that all enzyme providers give to the nutritionist you have to understand where this is coming from. For phytases the phosphate liberated is the main effect but energy comes from the reduction of the antinutritional effect of phytate IP6. The matrix value depends on the ability of the enzyme to breakdown IP6 before it binds with calcium, protein and starch. Also true, more phytate you have more active phytase you will need to reduce these antinutritional effects. So we should measure the phytate present in the final feed, to correlate as well with the "matrix value".
For "carbohydrases" (enzymes that degrade carbohydrates) the effects are more complex, so you have to analyze each enzyme individually. Amylase breaks down starch and should be used to complement the endogenous amylase from the animal, the matrix value will depend on the age of the animal and the diet composition (characterization of the starch is important to understand this). Also, it could be used to control glycemic index in swine if you use less digestible starch (starch from peas is a good example) that could be degraded by the exogenous amylase at the distal jejunum.
Finally, fibre degrading enzymes such as xylanase glucanase and mannanase. All depend on substrate concentration, antinutritional effects they solve and prebiotic effects. These are quite long so they should be discussed in a separate discussion.
And last but not least proteases, the main effect is to make protein more digestible, so the matrix value should be applied on the digestibility of the raw material or final protein. One misconception is to do this directly to the amino acids. Proteases rarely cleaves protein to that degree, most often they will produce polypeptides. This is not a bad thing, in humans polypetides (from animal origin) have been found to boost the immune system. However, as far as I know, there is no research in this area for monogastric animals.

Finally my conclusion: only apply the matrix value when you understand where is comming from


Sorry the long comment.

Dimcho Djouvinov
AB Vista
19 de enero de 2020
Dear Uloma, Different enzyme products differ in their thermostabilty. One needs to apply a product which is able to survive the regime of heat treatment in process of pelleting. The other option is to spray a liquid product post pelleting.
Juarez Donzele
Universidad Federal de Viçosa - UFV
20 de diciembre de 2019

Dr. Luis, I fully agree with your consideration that changes in the microbiota, favoring the animal, is an important effect of enzyme action. I even think that this aspect should always be considered when presenting articles discussing the effect of enzymes on animal performance. Congratulations.

Luis Fernando Vergamini Luna
Opta Alimentos e Insumos
9 de diciembre de 2019
Gentlemen, just to add spice in the discussion we could also consider the microbiota as an important consumer of enzymes effects. Both phytases and carbohydrases will impact in the performance of established microbiota patterns, that seem to be specific to each production unit.
Dimcho Djouvinov
AB Vista
27 de noviembre de 2019

Dear Lokare,

For the proper application of phytase one needs to know the matrix values of the product, the phytic P levels in the feed and the goal of the production: performance or cost savings.

Rafael Duran
IFF - International Flavors & Fragrances
14 de noviembre de 2019
Aaron, I found your comment absolutely key; we, so many times get tied to endless discussions on which should be the level of enzyme addition without paying attention to the amount of potentially reactive substrate. Thanks and take care. Rafa.
Aaron Cowieson
dsm-firmenich
4 de noviembre de 2019

For sure enzyme responses are non-linear but in the range, we test them in animal nutrition they occasionally appear linear. I think it is crucial to also examine available/reactive substrate concentration when interpreting enzyme response. Systems may be saturated with the substrate in which case enzyme responses may be exaggerated across a wide range of inclusion concentrations, or they may be saturated with enzyme (low substrate concentrations) in which case the enzyme effects may reach a plateau very quickly. Relative substrate/enzyme concentrations should be quantified as often as practically possible before concluding on optimum doses. The next moving part is the limiting nutrients in the diet and which biological response you want to measure as an indication of enzyme value e.g. FCR, uniformity, digestibility, bone ash, etc. In the enzyme domain we have not been as consistent as we should have been in measuring and reporting these points in a systematic way.

Gene Pesti
University of Georgia
26 de octubre de 2019

I think everyone in this discussion made good comments. It seems to me that all that is needed is an underlying theory to fit all the various pieces into. This is the same for phytase and all the other enzymes:
First, it should be accepted that responses to enzymes follow Michaelis-Menten kinetics. Enzymes do not give linear responses. This was very nicely illustrated by Shirley and Edwards, Jr. (Graded Levels of Phytase Past Industry Standards Improves Broiler Performance, 2003 Poultry Science 82:671–680). Ignoring this approach, animal nutritionists seem absolutely fixated with the linear programming least-cost paradigm of feed formulation. They have just got to find a single number for everything in their feed formulation problem. A good metaphor? Round pegs into square holes? They want to drive in screws, but their only tool is a hammer? Animal nutritionists tend to like biology much more than mathematics. Our brains like to work with straight lines in two dimensions. But the linear programming approach of finding one number to put in a matrix just doesn’t work in this case: “However, this approach is flawed from the economic perspective because it implicitly assumes that there is a single relative value of the sources, regardless of the cost of feed components and the price of live birds” (Vedenov & Pesti, An economic analysis of a methionine source comparison response model, 2010 Poultry Science 89:2514–2520).
Second, once it is accepted that the responses are not linear, it should be a simple matter of applying production economic theory to the curves to find economic optimums (Pesti & Vedenov, An economic comparison of several models fitted to nutritional response data. J. Anim. Sci. 2011, 89:3344–3349). Transforming complex equations into economic space is just not what nutritionists want to do. And with ingredient and meat and egg prices changing daily, economic optimums change daily. I am glad I don’t have to explain that relative values are changing daily to a purchasing agent, but such a discussion may prove prudent.
Third, to try to understand the economic implications of the technical problems observed in animal nutrition, my approach was to team up with a very good agricultural economist, in these cases, Dmitry Vedenov. It is not easy to get even agricultural economists to understand the finer points of animal nutrition, like FTU’s. And it is not easy to understand exactly what they mean when they start talking in terms of Greek symbols. But they are really good at solving non-linear problems. With large sums of money at stake in using the right products at the right levels, it may be worth considering involving a professional economist in the decision-making process.

Edwin T Moran
Auburn University
24 de octubre de 2019

Each phytase has an optimum pH with ftu’s conveying its relative activity under that specific condition. Phytases first act during storage in the crop with pH’s varying between 4-6 over varying durations. This ingests is conveyed into gizzard where pH’s decrease to 2-3 again over varying durations. Phytases of different pH optima continue to function through crop and gizzard only to varying extents. The Ftu units simply approximate expectations of action through highly variable terms of “gastric digestion.” Don’t be surprised with results varying with any defined ftu.

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