LALLEMAND ANIMAL NUTRITIONwww.lallemandanimalnutrition.com

SPECIFIC FOR YOUR SUCCESSLALLEMAND ANIMAL NUTRITION / FEED UPDATE #48 JANUARY 2019

LALLEMAND ANIMAL NUTRITIONwww.lallemandanimalnutrition.com

SPECIFIC FOR YOUR SUCCESS

Welcome to the organic

selenium jungle!

LALLEMAND ANIMAL NUTRITION / ORGANIC SELENIUM JUNGLE 2

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A. WHAT IS ORGANIC SELENIUM?Organic Se is a generic term that covers sources where the Se atom is chemically bound within an organic molecule as is the case in nature (in plants and animals), as opposed to mineral Se sources. Within organic Se sources, two major categories are Se-enriched yeast and synthetic organic Se.

a) Se-enriched yeastUntil recently, Se-enriched yeast was the only organic Se source available on the market and has been authorized for use in feed in the EU since 2006. It is used both in human and animal nutrition. Yeast enriched with Se imitates what happens in nature every day but in a fully controlled way. Plants use inorganic/mineral Se from the soil and incorporate it within amino acids (Se atoms replacing a sulphur atom within certain amino acids to form “seleno-amino acids,” for example selenomethionine (SeMet) and selenocysteine (SeCys)). These amino acids can then be incorporated within seleno proteins. The principle is the same with yeast. When adding an inorganic Se during fermentation, the yeast cells incorporate it as organic seleno compounds. Feeding Se-enriched yeast to animals is quite natural, as the profile of different seleno-amino acids is similar to what they find in plants. Numerous studies have demonstrated the benefits of Se-enriched yeast in terms of bioavailability and efficacy when compared to inorganic Se.

b) Are all Se-enriched yeasts the same?One could think that all Se-enriched yeasts are the same, but they can differ very much in terms

of production process, visual aspects, purity, quality, and, as a result, in their bioavailability or assimilation by the animals. If the principle of producing Se-enriched yeast seems straight forward, producing highly concentrated Se-yeast that meets high quality criteria requires a specific process that relies on the yeast production expertise of the provider. In addition, not all yeast strains are the same, nor do they yield the same level of organic Se compounds. Then, when using a specific yeast strain, following adapted production processes and fermentation conditions, high Se concentrations can be achieved. During this process it is critical to find the optimal balance between adequate Se uptake by the yeast cells while minimizing Se rejection in the waste water (see text box page 5 to learn more about the Se-enriched yeast production process).

Producing high quality, concentrated Se-enriched yeast is the fruit of specific process development. Changing one parameter slightly (e.g. temperature, pH, aeration, or Se feeding regime) can significantly impact the quality of the end product. Therefore, the production process and the quality of the end product should be thoroughly controlled. For example, analysis of the total Se and SeMet contents of each production batch is absolutely crucial to guaranty a high-quality product to the users. Even though it is not the only organic Se compound in Se yeast, SeMet level is a good indicator of fermentation performance and should remain consistent from batch to batch. The premium Se-enriched yeast ALKOSEL produced by Lallemand Animal Nutrition contains at least 98% of organic Se in the form of SeMet (63%), and other organic Se compounds, such as SeCys (37%). When selecting a Se-enriched yeast source, a certificate of analysis showing results for the actual batch should be mandatory.

1 Certificate of analysisfor the batch

Light beige color

100% inactivated yeast

Microbial quality

4 criteria indicating good quality Se-enriched Yeast:

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�introductionWhen talking about organic selenium (Se), the three words ‘bioavailability, quality and price’ are always mentioned within the first three sentences. More and more organic Se solutions are offered in the market as the use of organic Se has increased greatly in recent years. Nutritionists are aware of the benefits of feeding organic Se to animals instead of inorganic, mineral sources. However, when it comes to selecting the best organic Se source, it can be tricky. There are more and more options on the market with different specifications and price, and nutritionists can find themselves in the middle of a real organic Se jungle where it can be difficult to decide which solution might bring the best price-to-performance ratio.

How to compare apples with apples and which criteria should nutritionists rely on to assess Se quality?This article aims to give an overview of the organic Se sources available in the European market and bring some tips on assessment criteria.

Welcome to the organic selenium jungle! How to identify the right organic selenium solution

3LALLEMAND ANIMAL NUTRITION / ORGANIC SELENIUM JUNGLE

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Even though it is not the main criteria, visual aspects can also be a good indicator of quality: a light beige color is a sign of good quality product. A darker, brown color can be a sign of lower digestible Se-yeast. As molasses (dark brown) are used in the fermentation, insufficient washing at the end of production can lead to residues of sugar in the Se-enriched yeast cream. When drying this cream, sugar and protein will cause a Maillard reaction that can reduce digestibility and, therefore, less Se will be available to the animal (Figure 1).

c) Synthetic organic selenium productsIn the last few years, synthetic organic sources of Se have entered the market, such as SeMet. These are produced by chemical synthesis. The percentage of organic Se is similar to Se-enriched yeast (>98%). In contrast to Se-enriched yeast, which contains different seleno-amino acids in addition to SeMet, synthetic organic Se sources consist of a single seleno-amino acid (i.e. SeMet), either pure, as hydroxy-analogue, or as a chelate with zinc.In the European Union, both Se-enriched yeast and synthetic organic sources are considered as ‘organic sources of Se’ and as equivalent in terms of bioavailability. For that reason, the maximum inclusion rate of Se per kg complete feed via such sources is established at 0.2 ppm. Finally, it is important to mention that in the European Union, unlike Se yeast sources, synthetic Se sources are not allowed for use in organic farming under the current regulation.

B. TRANSFER RATE: THE GOLD STANDARD FOR ASSESSING SELENIUM BIOAVAILABILITYIn the end, it is important to make sure the Se from the animal’s diet is well assimilated and reaches the organs: this is defined as bioavailability. So, how to assess the bioavailability of a Se source, whatever its form? Many comparison studies assess the efficacy of a Se source by measuring Se concentrations in different tissues (eggs, milk or muscle). This could be misleading as the Se concentration alone is an inadequate parameter to look at. Why? Let’s take an example: Two cows receive a different Se source. Cow A produces 30 kg milk per day with a concentration of 76 µg Se/kg. Cow B produces 34 kg milk per day with a concentration of 70 µg Se/kg. If we only look at Se concentration in milk, Cow A has a higher concentration. Therefore, the Se it receives is perceived as being more bioavailable.However, the total amount of transferred Se into the milk was higher for Cow B (Table 1). Finally, looking at the daily excreted Se content is still not enough as the feed intake might have been different and, therefore, the level of Se intake as well.Therefore, the most accurate way to compare the efficiency of a Se source is to compare their transfer ratio. The transfer rate takes into account the Se concentration of a tissue, the weight of this tissue, as well as the feed intake and the Se concentration in the ration.

Transfer rate = Quantity of Se exported in animal products

(tissue Se concentration x tissue weight)

Quantity of Se ingested by the animal (feed intake x feed Se concentration)

Going back to our previous example, let’s assume that Cow A ingested 21 Kg of feed at 0.3 ppm Se and Cow B 23 Kg at 0.35 ppm: table 1 shows that finally cow A has the highest transfer rate.

Figure 1.Different Se-enriched yeast products proposed for the feed market.

Figure 1

Cow A Cow B

�Feed intake (kg/d) 21 23

Se concentration of feed (mg/kg) 0.3 0.35

Se intake (mg/d) 6.3 8.05

Milk yield (kg/d) 30 34

Milk Se concentration (mg/kg) 0.076 0.07

Milk Se content (mg/d) 2.28 2.38

Transfer rate (%) 36% 30%

Table 1. Example of Se transfer rate calculations

LALLEMAND ANIMAL NUTRITION / ORGANIC SELENIUM JUNGLE 4

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Figure 3

Figure 3. Se concentration (top) and transfer rate into the breast muscle (bottom) of different organic Se sources (fed at 0.2 mg Se per kg complete feed) after 14 days supplementation to broiler chicks (p<0.001).

Figure 2

Figure 2. Se concentration (top) and transfer rate into the breast muscle (bottom) of different Se-enriched yeasts (fed at 0.2 mg organic Se per kg complete feed) after 14 days supplementation to broiler chicks (p<0.001).

a) Assessing different Se-enriched yeast products

A study in broilers comparing different sources of Se-enriched yeasts, fed at the same level, has shown a difference in terms of Se transfer rate (Figure 2). All the Se yeasts tested followed similar specification: 2,000-2,400 ppm total Se, of which >63% is reported as SeMet. For few selenised yeasts it is even >70 % SeMet. However, some products differ in their visual aspect and sample analysis sometimes indicate SeMet contents below the 63% or 70% value stated on the label.

SeY1 is an inactivated Se yeast with a dark color and a low SeMet content (35% SeMet measured). Se transfer rate of SeY1 (21.2%) was not statistically different from inorganic Se (SS).

SeY2 appears as a granulated powder. Moreover, microbiology analysis has shown that the yeast is not fully inactivated (high CFU count). Even though the measured SeMet content is high (69% SeMet), the Se transfer rate was the lowest (7.4 %) compared to all other sources, confirming the limited absorption of Se from Se-yeast products, which the yeasts have not been properly inactivated.

ALKOSEL is an inactivated Se-enriched yeast with a high SeMet content (73% SeMet) and light color, showing the highest Se transfer rate in the study: 49.4%.

b) What about synthetic organic Se sources?

Many comparison studies between Se-enriched yeast and synthetic organic Se sources have been performed in the past. However, most of them were based on Se concentration in tissues and not the Se transfer rate. In the above-mentioned broiler study, the bioavailability of three different synthetic organic sources containing 100% SeMet (Zn-SM, SM1 and SM2) was also assessed.

There was not a significant difference between the Se-enriched yeast ALKOSEL and the synthetic SeMet regarding the Se concentration in the muscle. However, when taking into account Se transfer rate, differences are evidenced. Within the group of synthetic products, SM2 resulted in the highest Se-transfer rate (37%) compared to SM1 (34%) and Zn-SM (23%). Interestingly analysis of SM1 and Zn-SM did not show the expected >97% SeMet values, but instead 76% and 69% SeMet levels, respectively. It needs to be further investigated if the remaining Se is present in organic or inorganic form. (Figure 3)

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LALLEMAND ANIMAL NUTRITION / FEED UPDATE #48 JANUARY 2019LALLEMAND ANIMAL NUTRITIONwww.lallemandanimalnutrition.com

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�� To know more... How do we produce Se-enriched yeast?

This comparative study confirms previous benchmarking studies with dairy cows (IRTA, unpublished); and laying hens (Figure 4) (Barbé et al. 2017), showing that high quality Se-enriched yeast gives highest transfer rate as compared to synthetic organic Se sources. It indicates that SeMet may not be the only important compound for Se metabolism in animals. Indeed, analyses have shown that, besides SeMet, the Se-enriched yeast marketed by Lallemand, i.e. ALKOSEL, contains other forms of organic Se, in particular selenocysteine, and Se metabolic pathways in the body involve not only SeMet but also other amino acids, in particular selenocysteine. Therefore, the combined presence of SeMet, SeCys and other organic Se forms in ALKOSEL could offer optimal balance for Se uptake and utilization by the animal, explaining its superior bioavailability compared to the other sources Se tested.

did you know?ALKOSEL, the Se-enriched yeast produced by Lallemand, has been adopted by the Canadian National Research Council as the Certified Reference Material, or CRM*, for the analysis of Se-enriched yeast. *CRMs are used as part of every chemical measurement protocol for the evaluation of measurement precision and the calibration of analytical instruments. Laboratory analysts regard CRMs as the gold standard by which reliability of their results is authenticated.

Figure 4

�conclusionThe organic Se jungle is dense, but a few guidelines can help operators to find the right solution.

A proof of quality (certificate of analysis and not certificate of conformity only) should be mandatory for every production batch for all producers of Se-enriched yeast and synthetic organic Se sources. This avoids products that do not fulfill the claimed specifications.

Once the quality - proven with a certificate of analysis - is in line with the specifications defined in the legislation, nutritionists should then assess the offers, mainly by comparing the prices based on the true content of organic Se.

However, until this becomes a standard in the feed industry, nutritionists should at least check the visual aspects and if possible analyses of the products in independent expert laboratories. This will help find an organic Se solution that brings the best value for the money.

Figure 4. Se bioavailability (transfer rate into eggs) for ALKOSEL, sodium selenite (SS) and synthetic SeMet sources (SM1 and SM2) (Barbé et al., 2017).

REFERENCEBarbé F., Sacy A., Poulain S., Chevaux E., Castex M. Comparison of Se bioavailability in laying hens fed different organic Se sources. 21st European Symposium on Poultry Nutrition 2017, Salou / Vila-Seca, Spain, May 8-11, 2017.

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Lallemand Animal Nutrition is committed to optimizing animal performance and well-being with specific natural microbial product and service solutions. Using sound science, proven results and knowledge, Lallemand Animal Nutrition develops, produces and markets high value yeast and bacteria products - including probiotics, forage inoculants and yeast derivatives. These innovative solutions positively benefit animal nutrition and well-being, forage management and animal environment. Lallemand offers a higher level of expertise, leadership and industry commitment with long-term and profitable solutions to move our partners Forward. Lallemand Animal Nutrition is Specific for your Success.

Not all products are available in all markets nor associated claims allowed in all regions.

Inclusion of inorganic Seinto the fermentation media

Inside of the yeast cell:synthesis of Se-amino acids(SeMet, SeCys, etc.)

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Incorporation into the yeast protein as organic Se

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Yeast itself does not need Se and contains little of it. To produce Se-enriched yeast, an inorganic Se compound, such as sodium selenite, is gradually added to the yeast growth medium. The growing cells organically incorporate Se atoms within amino acids in place of sulphur (e.g. selenomethionine or selenocysteine). The production of Se-enriched yeast is a delicate process:

First, to ensure optimal incorporation of Se within yeast cells, scientists at Lallemand have selected a specific yeast strain, based on key criteria, in particular its ability to accumulate important levels of inorganic Se and the consistent distribution of Se within the different molecular fractions of the cells, as well as batch-to-batch reliability.

Then they developed a specific production process to ensure optimal and constant quality of the product. ALKOSEL is produced by fed-batch culture. Nutrients, including selenium, are supplied incrementally to the growing cells. It is key to add the right amount of selenium over the right time. Adding too little Se results in a low concentration of selenium in the final product, whereas adding too much could inhibit the growth of yeast.

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