Postbiotics in feed for healthy gut development and animal production

Choosing a product to promote the development and maintenance of a healthy gut in animals is essential for not only achieving optimal production performance but also to meet high health and welfare standards. Unlocking the inherent functionalities and nutritional values of feed ingredients, such as present in yeast, can already take us a long way. 

Dr. Hagen Schulze
Head of Innovation and Technical Livalta, AB Agri Ltd.

Dr. Aleksandra Szopinska-Morawska
Senior Innovation & NPD Manager
Livalta, AB Agri Ltd.

Supporting the healthy gut development in an animal will contribute to a further reduction of antibiotic use and consequently play a part in diminishing anti-microbial resistance in humans. No single product can replace antibiotics, however unlocking the inherent functionalities of certain feed ingredients such as yeast, can help an animal to attain its genetic potential whilst maintaining welfare and wellbeing.

Although pre- and probiotics have been around for many years, we now have the possibility of using an emerging category in animal nutrition – ‘postbiotics’. Postbiotics offer physiological benefits to the host and can comprise of products derived from deliberately inactivated and/or lysed microbial cells, and/or cell components (Aguilar-Toalá et al., 2018; Salminen et al., 2021). The efficacy of these products is through multiple mechanisms of action, such as contributing to modulation of the gut micro-organisms and the strengthening gut lining barrier function; optimising immune and metabolic responses; and potentially influencing appetite via the gut or central nervous system. Another advantage for use in animal feed derives from the fact that, because postbiotics are not live microorganisms, there is no concern about reduced efficacy due to feed processing.

Source organisms that are used in postbiotic production include inactivated whole yeast and its various components. Yeast (Saccharomyces cerevisiae) is a highly adaptable organism with multiple benefits that have been demonstrated in a large body of research over the last few decades. Their individual components have differing modes of action in the gut and can hence be a valuable asset to help maintain performance when the use of therapeutic and prophylactic compounds is reduced or restricted. Specifically, yeast cell wall (YCW) material has been shown to have the ability to bind to fimbriated bacteria in the gut, preventing attachment to the intestinal wall, which microorganisms require for proliferation and colonization. This can help to limit these organisms from reproducing to disease-causing and toxin-producing levels. According to published literature, this activity is due to mannan-oligosaccharides (MOS) in the YCW which have a high affinity for binding type I-fimbriae on certain disease organisms that are present in the gut (Agunos et al., 2007; Ganner and Schatzmayr, 2012; Ganner et al., 2013). Secondly, it has also been demonstrated that YCW components can help promote a robust immune system, both directly and indirectly, by increasing cytokine and immunoglobulin production (especially IgA) which boost immune responses to potential pathogens (Van Immerseel et al., 2009; Alizadeh et al., 2016).

Source organisms that are used in postbiotic production include inactivated whole yeast and its various components. Yeast (Saccharomyces cerevisiae) is a highly adaptable organism with multiple benefits that have been demonstrated in a large body of research over the last few decades.

In addition, the cell contents of yeast are beneficial as they include B vitamins (which are important in regulating stress response), minerals, nucleotides, high-quality protein and free amino acids. The latter promote palatability of feeds especially in pet food applications, and provide essential nutrients to gut epithelial cells to ensure the lining is robust and less prone to damage. Dietary nucleotides supplementation is known to promote the ileal gut wall development in the neonates (Superchi et al., 2012, Valini et al., 2021). They can contribute to repairing damage to enterocytes lining the gut, and hence are related to the efficient transfer of nutrients into blood and various cascade reactions in the gut-associated lymphatic tissue.

LivaltaTMCell HY40 is a postbiotic feed ingredient that is made from carefully selected non-GM Saccharomyces cerevisiae yeast strains from the Brazilian bio-ethanol industry, which is characterized by an exceptionally high (40%) cell wall (beta 1.3/1.6-glucans and mannan-oligosaccharides) and protein (min 36%) content. A carefully developed and controlled enzymatic treatment and drying process of the entire yeast ensures maximum functionality of the yeast cell wall fractions as well as the highest availability of the protein, nutrients and other bioactive molecules present inside the cell.

Pictures 1 a, b. Scanning electron microscope images to visualise changes of yeast cell morphology after enzymatic treatment; intact yeast cells (a) and enzymatically treated yeast – Livalta™Cell HY40 (b).

Pictures 1 a, b show the morphological changes of the yeast cells due to processing. Simultaneously, protein availability, measured by in-vitro pepsin digestibility, increased to 91% in Livalta™Cell HY40 compared to only 48% in the intact yeast raw material. In addition, more than 90% of the protein present in Livalta™Cell HY40 appear in a form of short peptides.

In addition, the specifically developed processing improves the functional properties of the YCW components, as demonstrated in recent ex-vivo studies measuring the effect of yeast products and components on adhesion of potentially pathogenic bacteria. For this assay, a layer of pig intestinal mucosa mimicking the surface of intestinal epithelium was used. The intestinal mucosa was incubated with radioactive labelled, potentially pathogenic bacteria, Salmonella enterica Typhimurium or Escherichia coli F4+, in the presence of selected yeast based products. After incubation, the mucosa samples were washed to remove the unbound radioactive bacteria and radioactivity was measured in each reaction well. The remaining radioactivity was proportional to the number of adhered potentially pathogenic bacteria.

Figure 1. An ex-vivo assessment of efficacy of yeast raw material and Livalta™Cell HY40 to limit adherence of potential pathogens to the intestinal mucosa. Targeted enzymatic treatment (E) of yeast enhances inhibition of E. coli F4+ bacteria adhesion.

Figure 1. shows the difference in percent bacterial adherence to intestinal mucosa in the presence of intact inactivated yeast raw material and processed yeast cells (Livalta™Cell HY40). The results demonstrate a strong improvement of yeast cell wall functionality; an efficient improvement of inhibiting bacterial adherence by the specifically developed processing steps.

Additional ex-vivo studies of pathogenic adhesion, were carried out to investigate the effectiveness of seven commercially available yeast products, tested at two different inclusion levels, 0.05% and 0.5% and compared to Livalta™Cell HY40. The yeast products were selected to cover major Saccharomyces cerevisiae yeast based product categories, such as inactive dried yeast (DY), autolysed yeast (AY) and yeast cell wall (YCW) products.

The results indicate that yeast-based products can generally reduce adhesion of potential pathogenic bacteria. Overall, however, the effects seem to be dose dependent and more pronounced in limiting the adherence of S. enterica Typhimurium (Figure 2) than of E. coli F4+. (Figure 3). All tested yeast-based products displayed different efficiency levels of inhibiting adherence when compared to negative control. Already at low inclusion level, Livalta™Cell HY40 shows strong inhibition of adhesion of S. enterica Typhimurium to the gut mucosa (Figure 2), compared to the other yeast products tested. The data for E. coli F4+ (Figure 3) shows that at a low inclusion level of 0.05% only two products (including Livalta™Cell HY40) result in a small but significant reduction of bacteria adherence compared with Negative Control. At a higher dose, all products create effects, although the 0.5% concentration of Livalta™Cell HY40 and Product D resulted in the highest inhibition, preventing over 90% of E. coli adherence.

Figure 2. Effect of yeast products on the adherence of S. enterica Typhimurium on piglet intestinal mucosa assessed by ex-vivo study. 100% of bacteria adherence to the intestinal mucosa is observed in the absence of yeast based test products (Negative Control). * indicate statistical difference to Negative Control at P<0.01. Product categories: DY = inactive dried yeast, AY = autolysed yeast, YCW = yeast cell walls.
Figure 3. Effect of yeast products on the adherence of E. coli F4+ on piglet intestinal mucosa assessed by ex-vivo study. 100% of bacteria adherence to the intestinal mucosa is observed in the absence of yeast based test products (Negative Control). * indicate statistical difference to Negative Control at P<0.05. Product categories: DY = inactive dried yeast, AY = autolysed yeast, YCW = yeast cell walls.

Of the yeast based products included in those studies, enzymatically treated (Livalta™Cell HY40) and autolysed yeast products (AY) seem to be more efficacious in inhibiting pathogenic bacteria adherence than yeast cell wall products. The potential role of available components of the yeast cell content, raw material source and processing can play in this context needs further in depth evaluations.

CONCLUSIONS
Choosing a product to promote the development and maintenance of a healthy gut in animals is essential for not only achieving optimal production performance but also to meet high health and welfare standards. Unlocking the inherent functionalities and nutritional values of feed ingredients, such as present in yeast, can already take us a long way. As above studies have demonstrated, dedicated development of yeast feed ingredients can provide a simple solution to complex problems; nurturing and protecting the animal whilst contributing to profitability and convenience for a farmer or feed manufacturer.

References and further information are available upon request.

About Dr. Hagen Schulze
Dr Schulze holds a PhD in Animal Nutrition from Wageningen University, the Netherlands. He has a wealth of experience in the animal feed and feed additives industries, having predominantly hold positions in research and product management. Since joining AB Agri/ Livalta in 2016, he is responsible for leading innovation and development of the product portfolio as well as technical support within the team. The emphasis of his present research activities are the evaluation and improvement of the nutritional value and functional properties of feed ingredients together with their impact on the welfare and wellbeing of the animal.

About Dr Aleks Szopinska-Morawska
Senior Innovation & NPD Manager at Livalta, AB Agri’s new business for responsible proteins. Aleks’ role aims to ensure the effective delivery of new products for the AB Agri/Livalta portfolio. She manages new product development and oversees the R&D activities for new products.
Aleks completed her PhD in Agricultural Science and Bioengineering at Catholic University of Louvain in Belgium and Postdoc at Luxembourg Institute of Science and Technology. Aleks has a background in biochemistry, microbiology and food/feed processing technologies.