Scientifically Speaking …


By Matthew Wedzerai


Matthew Wedzerai holds an MSc in Animal Science (Specialisation: Animal nutrition) from Wageningen University, The Netherlands. He also holds a Diploma in Pig husbandry & Animal Feed, PTC+ College, The Netherlands. He has 7 years’ experience in the pig husbandry and animal feed industry and has been a writer of articles based on scientific research since 2014.


BENEFITS OF DIFFERENT MULTI-ENZYME COMPLEXES IN POULTRY! At a moment where outbreaks of ASF are on the rise, the demand for poultry products is expected to increase. Among other strategies, this calls for better feed utilisation in poultry diets to reduce production costs. Studies with broilers have shown that dietary supplementation with multi-enzyme complexes containing NSP-degrading enzymes and phytase is efficient in releasing minerals (phosphorus, calcium), energy and amino acids. Since there is no one fixed or supreme multi-enzyme recommended, it is interesting to have insights on the benefits of different multi-enzyme complexes. These benefits are explained, here, in broilers and meat duck on growth performance, nutrient utilization and bone mineralization.


Why a combination? From studies, one type of enzyme, whatever the dose, cannot match the efficiency of a combination. The enzymes, though distinct in properties, have complementary effects. For example, although the modes of action and substrates of phytases and carbohydrases are different, their effects on diet digestibility and performance are complementary. Similarly, a combination of carbohydrases and proteases is expected to complement each other, considering, for example, in corn, starch granules are mainly found embedded in a protein matrix (Cowieson et al., 2018).


Quick overview of common enzymes used Phytase By reducing phytate in the diet with phytase addition, amino acids and minerals (mainly phosphorus and calcium) availability are improved, whilst reducing the cost of mineral sources, decreasing associated pollution from organic phosphorus content of manure.


Xylanase and β-glucanase It has been shown that the anti-nutritive effects of viscous cereals such as barley, wheat, rye, oats, and triticale are associated with raised


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intestinal viscosity caused by soluble β-glucans and arabinoxylans (Zarghi, 2018). Xylanase mainly degrades arabinoxylans, increasing energy digestibility and reducing viscosity problems associated with NSPs. High dietary concentrations of insoluble NSPs present additional challenges for broiler nutrition, such as a reduced digestibility of proteins and lower energy density (Romero et al., 2014).


Amylase Improving the digestion of starch has a profound effect on the energy value of a given diet. In addition, exogenous amylase can help to reduce amino acid requirement for amylase synthesis which is particularly large for glycine and serine as pancreatic amylase is around 16%–17% Gly + Ser (Cowieson et al., 2018; Croom et al., 1999).


Proteases Exogenous proteases complement the activity of endogenous proteolytic enzymes. They improve the hydrolysation potential of feed proteins – resulting in improved feed utilisation efficiency and animal performance. Proteases improve animal performance through increased digestibility of crude protein, peptides and amino acids. The following sections will review the effects of multi-enzyme


complexes (mainly Natuzyme – produced by Bioproton) on nutrient utilisation, growth performance and intestinal morphology in poultry (ducks and broilers).


Effects on nutrient utilisation Meat duck The study of Zeng et al. (2015) (Table 1) shows the effect of a multi- enzyme complex consisting of xylanase, β-glucanase and phytase, on bone mineral content. In the same study, a similar trend was also observed for the availability of energy, protein and fat. The multi- enzyme complex improved a deficient diet (NC) to the level similar to a positive control (PC) diet.


Table 1. Tibia ash, calcium and phosphorus contents (%) of ducks at 35 days of age


Item


Basal diet1 PC NC NC


1


enzyme - -


+ Ash (%)


53.77a 50.10b 52.66a


Ca (%)


20.51a 18.96b 20.39a


P (%)


7.84a 6.98c 7.62a


: PC = Positive control; Negative control, NC = −100 kcal/kg, −2.5% DAA, −0.15 % avP, −0.12 % Ca; DAA = digestible amino acids.


Broilers Table 2 shows the changes in apparent ileal digestibility (AID) coefficients and ileal energy contribution of protein, starch, and fat in response to exogenous xylanase and amylase combinations without or with protease in broiler chickens fed diets with corn or wheat as the base grain. The digestibility of nutrients increases as the number of enzymes in the multi-enzyme complex increases (Table 2).


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