Carbohydrases and phytase make sustainable poultry


By Marcio Ceccantini and Sofia Zenagui, Adisseo


A new global enzyme solution improves feed digestibility, enabling significant reduction in dietary nutrient levels, and increasing nutrient retention. Therefore, broilers require less nutrients from feed and less natural resources; nutrient excretion is decreased, and sustainability in the poultry industry improved.


Summary Sustainable solutions for broiler production imply the use of numerous enzymes targeting anti-nutritional factors in feed. Phytase and carbohydrases remain the most advanced solution for that purpose. Indeed, as these enzymes act on different substrates, there is no doubt on their complementarity to reduce anti-nutrients in feed and increase diet digestibility. Such a combination results in significant improvements in the sustainability and performance of poultry production. Diets fed to broilers, and also to other livestock, contain a


considerable number of indigestible fractions. In fact, 20 to 25% of the organic matter is unavailable for absorption in broilers. As a result of this, in the last 3 decades, several enzymes have been developed to improve feed digestibility. They have opened up options of using various raw materials, to reduce feed costs and take advantage of local alternative feed ingredients. Simultaneous use of different types of enzymes has been a challenge mainly due to the lack of technical data on the optimal way to combine them, resulting in undervaluing this kind of solution. The use of a global enzyme solution containing a super-dosed phytase and a complex of carbohydrases has the potential to significantly reduce the carbon footprint of poultry production.


Why combine carbohydrases and phytase? The ability of efficient multi-enzyme solutions to improve global feed digestibility is known as the feedase effect. By reducing the indigestible fraction of feed, as well as anti-nutritional factors, more nutrients are released. Whilst the modes of action and substrates of phytases and


carbohydrases are different, their effects on diet digestibility and performance are complimentary. The nutrient-captured mechanisms by non-starch polysaccharides and phytate are not the same, thus when degrading both the nutrient release is higher. In terms of cost- effectiveness, it is worthwhile using both classes of enzymes as long as appropriate re-formulation is employed. The feedase approach aims to consider the various enzymes as a global enzyme solution and define a unique nutritional matrix for it, instead of cumulating individual matrix values of each enzyme.


Why adding phytase in high dose is still effective in presence of carbohydrases – going further into the feedase effect? By reducing phytate in the diet with phytase addition, amino acids and minerals (mainly P & Ca) availability are improved, whilst reducing cost of sources of mineral, decreasing associated pollution from organic


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phosphorus content of manure and leaving more space for vegetable raw materials. By increasing the standard inclusion level of phytase (super- dosing), phytate and its breakdown products, are quickly and further degraded. Phytase superdosing is valuable to quickly destroy phytate and to constrain new indigestive complexes. Anti-nutritional effects are reduced, and performance further improved. At the same time by breaking down plant cell walls, carbohydrases


liberate more nutrients. By reducing viscosity of the digesta, carbohydrases help to reduce digestive problems associated with feeding mainly on wheat and barley diets. In addition, the short polysaccharides, coming from the action of carbohydrases on fibrous compounds, have a prebiotic effect favouring beneficial microflora. These classes of enzyme have distinct but complimentary effects


– one type, whatever the dose, cannot substitute the efficiency of a combination. Both kinds of enzyme degrade indigestible parts of the diet – in doing so they increase energy availability and nutrient value of the feed. In order to take full advantage of this, the enzymes need enough ‘room’ in the diet. To maximise economic benefits, specifications should be reduced in terms of metabolisable energy (ME), digestible amino acids (dAA), available phosphorus (avP), calcium (Ca) and sodium (Na).


The evidence of feedase efficacy A broiler pen trial was carried out at Zootests, France - to evaluate the effect of a global enzyme solution containing a complex of several carbohydrases (containing specific xylanases, glucanases and arabinofuranosidases) and a super-dosed phytase (1000 ftu). The formulation of the trial diets had lower specifications, compared to the positive control (Table 1). ME was reduced by 3, 4 or 5% and dAA by 3, 4.5 or 6%, in 3 different treatments, along with a fixed reduction of 0.174% avP and 0.157% Ca. These three groups were compared with or without the multi-carbohydrase-phytase complex (MCPC). A positive control was raised in parallel. All treatments used a corn-wheat-soybean based diets. Growth performance, carcass characteristics and mineralisation were measured, and results statistically compared.


Table 1: Negative control diets of the trial performed at Zootests, France, 2017


Corn and wheat- based diets


NC1 NC2 NC3


Reduction, % vs PC


ME 3 4 5


Dig. AA 3


4.5 6


Reduction, % unit vs PC AvP


0.174 0.174 0.174


Ca


0.157 0.157 0.157


The reduction of ME, dAA, avP and Ca in the diet significantly


reduced the body weight gain and increased FCR (P < 0.0001; Figure 1) similarly for the 3 NC diets; with no effect on feed intake. At 42 days


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