Optimize overall digestibility of the feed to capture its nutritive full value

1. Feedase: from the indigestible fraction to the global feed enzyme approach

Providing insights into the indigestible components such as phytate and dietary fiber and their interaction in poultry feeds is key for capturing the full value of exogenous enzymes. In order to estimate the potential of enzymes in animal diets, nutritionists must first know what fraction of nutrients is not digested and present antinutritional properties. As exogenous enzymes aim at releasing part of non-digestible components into digestible nutrients, knowing the amount of non-digestible nutrients help to evaluate the potential of such enzyme response. Considering several exogenous enzymes as a unique enzyme solution, which breakdown the antinutritional fraction and releases nutrients from it, has demonstrated to be the best way to evaluate the feed digestibility improvement. This vision is described as the feedase approach. Feedase is about considering the whole feed for a global enzymatic solution, resulting in an improvement of digestibility of all nutrients, including fat, starch, proteins, phosphorus, etc… With this new approach, the enzyme effect is linked to a specific substrate, but enzyme effect is associated with indirect effect on nutrients (i.e. fat, starch, proteins, phosphorus) to the complementary actions of enzymes.

2. Increasing overall feed digestibility with a multi-carbohydrase enzyme

To demonstrate the efficacy of a multi-carbohydrases (Rovabio® Advance®), a digestibility trial was performed with Ross PM3 male broilers between 13 and 22 days of age, using the European Reference Method with ad libitum feeding and 3 days of total excreta collection (Bourdillon et al., 1990), at the experimental farm of Adisseo in Commentry, France. Birds were fed a common starter feed in crumbles based on wheat and soybean from 0 to 12 days, followed by a grower feed with either a simple composition (wheat and soybean meal) or a more complex composition (wheat, barley, rye, wheat DDGS, soybean meal, sunflower meal, rapeseed meal). Regardless ingredient composition of the diet, the addition of the enzyme significantly improved the energy utilization and the digestibility of several nutrients (Table 1).

*p<0.05¹ Rovabio® Advance L2
Ref: Cozannet et al. 2017, Poultry Science

This improvement was more important for the complex diets than for the simple diet. The improvement observed on energy utilization and digestibility of nutrients was related with arabinose xylose content 69.2 vs. 59.5 g/kg for complex and simple diets, respectively. To further validate the concept of global feed digestibility, the effect of Rovabio® Advance was evaluated in a standard wheat-based diet diluted with 3% of sand (Cozannet et al. 2018, Journal of Poultry Science). This study investigated the effect of Rovabio® Advance® on energy and ileal amino acid (AA) digestibility of a complete wheat/soybean-based diet in broilers. The commercial control diet was compared with a 3% nutrient-diluted version using silica as inert diluent. Digestibility of dry matter (DM), AA and gross energy (GE) were determined by analysis of feed, excreta and digesta. Ross PM3 broiler chicks were studied during the grower period and diet dilution did not increase feed intake. Fecal energy digestibility was similar (approximating 73%) for diets without enzymes (P = 0.99). However, apparent metabolizable energy (AME) content was significantly lower in the diluted versus control diet. Rovabio® Advance improved energy utilization (P < 0.001), leading to an increase of AME content for both the diluted and standard diets. AME content of diluted diet with Rovabio® Advance was similar to that of the standard diet without enzymes (P = 0.98), demonstrating the ability of this enzyme to fully compensate the 3% nutrient dilution (Figure 1).

At ileal level, AA digestibility was around 75% across all treatments. The addition of the multi-carbohydrase increased AA digestibility by an average of 3.3% (P<0.001, Figure 2). Rovabio® Advance® restored nutrient availability when the nutrient content of a diet was diluted by 3%. This study highlights the importance of considering the entire nutrient matrix when global enzyme solutions are supplemented to diets.

3. Increasing overall feed digestibility with a multi-carbohydrase enzyme combined with phytase

To evaluate the effect of an enzyme containing a complex of a multi-carbohydrase (specific xylanases, beta-glucanases and arabinofuranosidases) and an optimal dose of phytase (1000 FTU/kg feed), called Rovabio® Advance Phy , a broiler pen trial was carried out at Zootests, France. The formulation of the trial diets had lower specifications, compared to the positive control (Table 2).

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% units avP and 0.157% units 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 bone mineralization 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; Figure 3) similarly for the 3 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 enzyme irrespective of the diet reformulation. This trial demonstrated that adding Rovabio® Advance Phy to broiler diets would allow significant reductions in the specification up to a 5% reduction in ME, 6% in dAA, 0.174% units in avP and 0.157% units in Ca. The study showed that the enzyme combination makes it possible to reduce feed costs.

The use of alternative ingredients that are very sensitive to enzymes because of higher quantity of substrates looks to be a promising strategy to reduce cost. Their low digestibility can be compensated by the addition of enzymes and they can provide non-negligible nutrient contents. In corn-soy-wheat diets containing 6% of sunflower meal, Rovabio® Advance Phy could allow saving up to 27€/t of feed without any impact on animal performance.

By Dr. Pierre Cozannet and Dr. Maamer Jlali, Feed Digestibility expert, Adisseo

Reference :

Jlali et al. (2020). Evaluation of a multicarbohydrase and phytase complex in reduced energy, amino acids, available phosphorus and calcium diets fed to broilers. Livestock Science 241 (2020) 104227.

Product names and availability may vary by region, please contact your local Adisseo representative for more information.