Optimizing the overall feed digestibility: Tips for capturing its full nutritive value

Cereals and oilseeds are the main ingredients in animal feed, but they contain antinutritional factors and indigestible substrates that can harm animal performance. To improve feed digestibility, it’s important to evaluate these components precisely and consider using exogenous enzymes as a solution.

MASTER RAW MATERIAL VARIABILITY
It is well known that there can be significant variations in nutritional values between batches of raw materials, even within the same plant family. The challenge for nutritionists and feed formulators is to have reliable way to monitor and control raw materials quality so that they can be used accurately in feed formulations, allowing animal performance objectives to be met as efficiently as possible.

Nowadays, NIR analysis tools are readily available to feed mills. NIR is ideally suited to complement and support quality control plans that use wet chemistry.

One of the advantages of NIR analysis is that it is possible to carry out predictions, on the same spectrum, for analyses which are not commonly requested or impossible to perform in wet chemistry. This is the case for the digestibility of amino acids and energy, or the determination of phytic phosphorus. This aspect is particularly interesting, because for some raw materials, the use of table values or predictive equations may not represent the reality.

For example, there isn’t a good correlation between total lysine and digestibility of lysine (SID coefficient) in soyabean meal (SBM) or corn DDGS (cDDGS) (Figure 1). This means that estimating digestible lysine from total lysine isn’t very accurate. For a soybean meal at 2.9 total lysine, the digestibility coefficient can vary from 75.6% to 97.1%.

For phosphorus, it’s not possible to predict phytic phosphorus content based on total phosphorus determination as presented in the graphs figure 2 (R² are very low). Thus, determining the potential of phosphorus released by a phytase can be challenging. The Figure 2 show that there is no correlation.

To go further, Adisseo has developed over 30 years a robust Near Infrared Spectroscopy (NIRS) called Precise Nutrition Evaluation (PNE). The system integrates calibrations built not only on common chemical analyses, but also in vivo digestibility tests – on growing broilers for the Apparent Metabolizable Energy (corrected or not from nitrogen – AME and AMEn) and caecectomized cockerels for amino acid digestibility. Adisseo combined the first set of chemistry analyses with animal trials, by feeding animals with the same feed samples, then collecting the feces to measure the difference between what was ingested and what was excreted.

PNE is unique, as of 2023 it comprises more than 400,000 feed samples from all over the world providing a general overview of the raw material quality worldwide. This online tool offers nutritionists a fast, discriminating way to monitor the variability of the raw materials and provide digestibility data to further improve the nutrient matrix and formulate as precisely as possible.

Now that we have the capacity to precisely formulate our animal feed, one should wonder how to extract the maximum value of the feed to better serve animal performance?

INCORPORATE FEEDASE: THE GLOBAL FEED DIGESTIBILITY APPROACH
Within poultry feed, 20 to 25% of the ingested feed fraction is indigested. This indigestible fraction of feed corresponds to compounds which are either totally or partially digested. Many reasons may explain a lower digestibility performance such as heat damage of the feed, passage rate of the digesta, lack of enzymatic activity, or the presence of anti-nutritional factors such as trypsin inhibitors, phytates or dietary fibers. Those anti-nutritional factors may inhibit endogenous enzymes activity, favor some nutrients bounding or increase digesta viscosity, thereby negatively affecting the digestibility of the feed.

Knowing what fraction of nutrients is not digested and present antinutritional properties, and providing insights on the indigested compounds interaction in poultry feed is key for capturing the full value of exogenous enzymes.

An internal study analyzing the effects of eight different anti-nutritional factors included at different levels in poultry diet, showed that for each percent of phytate present in the diet, the digestibility was decreasing by 0,48% as AMEn, thus decreasing the overall energy of the diet.

Therefore, knowing the amount of non-digestible nutrients helps to evaluate the potential of exogenous enzyme response.

As an example, dietary fibers act as anti-nutritional factors, hence need to be degraded or digested to eliminate their negative impact. However, there are many kinds of dietary fibers (arabinoxylans, xyloses, B-glucans etc…), and each of these substrates needs a specific enzyme to be degraded. Unfortunately, due to the complex interactions happening between the enzymes, the substrates, and the gut environment, we cannot claim a certain additive effect from the inclusion of several types of enzymes.

For this reason, 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… In other words, FEEDASE is composed of several complementary activities aiming at increasing the overall digestibility of feed, by targeting the indigestible fraction of raw materials and anti-nutritional factors in degrading indigestible substrates and releasing nutrients.

To strengthen the FEEDASE concept, Adisseo has developed Rovabio^® Advance, a multi-carbohydrases enzyme which revolutionizes feed digestibility in any type of diet.

INCREASE OVERALL FEED DIGESTIBILITY WITH A MULTI-CARBOHYDRASE ENZYME
To demonstrate the efficacy of a mutli-carbohydrases (Rovabio^® Advance), a digestibility trial was performed with Ross 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).

This improvement was more important for the complex in terms of ingredient and dietary fiber composition 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 typical 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 broiler chicks were studied during the grower period and diet dilution did not increase feed intake.

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 typical diets. AME content of diluted diet with Rovabio^® Advance was similar to that of the typical diet without enzymes (P = 0.98), demonstrating the ability of this enzyme to fully compensate the 3% nutrient dilution (Figure 3).

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 4). 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.

SUMMARY
To achieve precise nutrition, it’s important to first understand the variability of raw materials. Adisseo’s PNE database, built on in-vivo calibrations, is a reliable resource that can help extract more value from raw materials for acute feed formulations. In addition, evaluating the indigestible fraction of feed and anti-nutritional factors is crucial for precision in animal nutrition. Exogenous enzymes, other than protease, are particularly interesting for improving apparent metabolizable energy and increasing amino acid digestibility in monogastrics. Multi-carbohydrase complexes such as Rovabio^® Advance used within a FEEDASE approach have demonstrated significant improvements in protein and amino acid digestibility.

About Florian Bastit
Florian Bastit is the Global Technical Manager of Precise Nutrition Evaluation tool for Adisseo. He earned his MSc in zootechnics and animal nutrition from the agricultural engineering school ESA Angers, France, in 2012 and has been working in animal nutrition since then. He first took a position in a feedmill in France as a formulator and a technical advisor for poultry farmers, then worked for French premixers as poultry specialist in France and abroad for 6 years. Florian joined Adisseo beginning of 2021 as Global Technical Manager, in charge of the PNE tool development and communication. His nutritional background helps him to better understand customers’ needs in terms of raw material evaluation for their feed formulation.

About Baris Yavuz
Baris Yavuz is animal nutritionist, graduated from animal science in university of Uludag,Turkiye in 2001. Working in feed industry as formulation and quality assurance manager many years, he has joined Adisseo in 2016 as regional technical manager for Eastern Europe, Turkiye and Israel. Yavuz is currently working in Feed Digestibility Department in Adisseo as Scientific Solution Developer, in charge of global technical support. He is the technical consultant of Adisseo’s phytase development project. He is in close contact with Adisseo R&I and different research centers around the world, in order to develop solutions for local and global needs.

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