Multi-enzyme solutions for sustainable poultry

Diets fed to broilers, and other livestock, contain a considerable number of indigestible fractions. In fact, 20 to 25% of the organic matter is unavailable for absorption in broilers. Due to this, several enzymes have been developed to improve feed digestibility over the last 3 decades. This has 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 poultry production carbon footprint on the earth’s resources.

Photo: Mark Pasveer

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 at considering 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.

Further in the feedase effect

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 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 the performance is 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 so doing 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 three 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 diet. Growth performance, carcass characteristics and mineralisation were measured, and results statistically compared.

The reduction of ME, dAA, avP and Ca in the diet significantly reduced the body weight gain and increased FCR (P < 0.0001) similarly for the three NC diets; with no effect on feed intake. At 42 days of age these performance criteria were restored to the level of the positive control by the addition of the feedase – irrespective of the diet re-formulation. The lower specification diets (NC1, NC2 & NC3) significantly reduced carcass, breast, and leg weights of broilers at 42 days of age (P < 0.0001; Figure 1). The inclusion of the feedase returned the carcass traits to positive control levels in all cases. This trial demonstrated that adding this global enzyme solution to broiler diets would allow significant reductions in the specification up to a 5% reduction in ME, 6% in dAA, 0.18% in avP and 0.16% in Ca. The study showed that the enzyme combination makes it possible to reduce feed costs; whilst maintaining broiler performance, carcass yields and tibia characteristics.

Figure 1 – The addition of a multi-carbohydrase and phytase to re-formulated diets restored carcass, breast and leg yield to that of the control.

Reducing the environmental footprint

In this trial, the feed treated with enzymes had 25kg less soy oil, 8kg less phosphates and 20kg less soybean meal per each ton of feed, replacing it by 53kg of corn. This substitution represents saves close to 1.7ha of arable land/each 1,000t of feed produced, due to the differences in productivity of soy and corn. Moreover, with 1,000 t of feed, 8t less of phosphates was consumed, which is a limited natural resource.

A second impact can be considered on the manure. A supplementation of multi-carbohydrase could decrease the excretion of ammonia by 13%, and the feedase treatment compared to no enzymes in the feed, decreased the P excretion by 37%.

Considering that phytates and non-starch polysaccharides are the most relevant anti-nutritional factors in feed, decreasing its digestibility, the use of a multi-carbohydrase and phytase complex can save costs, without hampering performance. But it is also an effective way to improve sustainability, by decreasing the extension on arable land to produce feed ingredients, decreasing the N and P in manure.