Yeast walls and yeast extracts for animal health

Garzanti Specialties and Ohly for Feed and Pet Food markets

Reducing the usage of antibiotics in animals has undoubtedly been one of the hot topics in recent years.
In order to ensure excellent yields, and avoid problems linked to bacterial and viral infections, the most common practice until just a few years ago was to rely on antibiotics. This inevitably led to an overuse of these drugs and an emergence of serious consequences that had not been considered sufficiently – most importantly antibiotic resistance.
Growing consumer awareness of these issues, combined with legislative pressure to reduce the use of antibiotics, has led the sector to undertake research into viable alternative solutions to counteract the physiological problems typical in livestock and pets, without having to resort to antibiotics.

Solutions on the market today are in the form of Mannan-oligosaccharides (MOS) and β-Glucans: two naturally derived polysaccharides with proven beneficial properties for animal health.
Multiple scientific journals have demonstrated the benefits of these products on the physiological state of animals, demonstrating how yeast cell wall supplements improve their performance in terms of both average yield and feed conversion rates.

In collaboration with Ohly, one of the world’s leaders in functional yeast derivatives, Garzanti Specialties makes these products available in Italy for both the pet and the animal feed markets.
Let’s go into the details behind how these products are made allowing us to recognise the key factors that lie behind a truly quality product.

Yeast walls and yeast extracts

Traditionally, yeast cell walls were a by-product of the production of yeast extract.
Active yeast cells will lyse from the yeast enzymes when subjected to high temperature (AUTOLYSIS) or the addition of other enzymes (HYDROLYSIS). Once the lysis process is complete, the yeast extract (the intracellular soluble fraction) and the cell walls are separated by centrifugation before being dried.

The production of 1kg of yeast extract yields approximately 0.5kg of yeast cell walls.

At first, the effects of cell walls on the physiological welfare of animals was unknown. They were sold off at very low prices in liquid form because of their high protein content (20/30%), or were used as appetising stimulants, especially for pigs.
Only later, upon the discovery of their enormous functional value, did companies start to dry the product (increasing shelf life from around seven days to more than two years) and specialise in the concentration of MOS or β-Glucans.

How to recognise a quality product

The growing awareness of yeast cell wall derivatives as valuable tools to reduce the use of antibiotics in animals has led to a sharp increase in demand for these products on the market.
Many suppliers use of spent yeast from breweries, distilleries or bioethanol plants for the production of yeast cell walls and its derivatives. Raw materials that allow low prices, but in some cases can compromise the quality of the final product.
However, when looking for quality, the raw materials used is just one of the many aspects that need to be taken into consideration.
Yeast cell walls contain three main polysaccharides: Mannan-oligosaccharides (MOS), β-Glucans and Chitin. For a long time it was thought that the cell walls had a relatively static structure with limited changes in composition.

The reality is quite different: they are actually characterised by their heterogeneity, both in composition and structure. These two aspects, along with the raw material used become fundamental in distinguishing highly functional products, and consequently in obtaining the best results in the animals.
This strong heterogeneity between one product and another, both in terms of the composition (Mannans 25-70%, β-glucans 30-60% and Chitin 1-8%) and cell wall structure, is the reason why different end results are often observed in animals, despite the use of products that were considered to be similar.
This variability is mainly determined by the following factors:

• Yeast growing conditions (fermentation): the carbon source, temperature, pH and oxygen availability all have a strong influence on the presence of sugars in the walls, the structure of the polymers themselves, their degree of branching and the lengths of the branches themselves.
• Strain: the Saccharomyces cerevisiae species contains many yeast strains which have a significant influence on the final composition. Yeast extract producers, breweries and bioethanol producers each use their own strains; which contributes towards an enormous influence on the variability of the end-product composition.
• The production process of the cell walls: in general, there are two different production processes: AUTOLYSIS or HYDROLYSIS

In spite of the difference in production complexity favouring autolysis, the reality is the industry is increasingly turning to hydrolysis.
This process is used during the production of yeast extracts with a high nucleotide content (which are increasingly in demand). In addition, the use of spent yeast from bioethanol plants as the raw material for obtaining the cell walls, requires the addition of Exogenous proteases to lysate the cell wall as the yeast enzymes have been deactivated during the prior production process of bioethanol.
With exogenous enzyme supplementation, not only is yeast lysis obtained, but also hydrolysis occurs of the mannoproteins present on the outside of the yeast, which become soluble but don’t pass with the centrifugation into the yeast cell walls. MOS levels in hydrolysed cell walls is about 50% lower than levels obtained through autolysis.
The yeast cell walls are spheres, and therefore the functional carbohydrates present on the outside determine its functionality.

Autolysed yeast cell walls contain MOS on the outside, while hydrolysed yeast cell walls contain a mixture of MOS and β-glucans on the outside (known as mixed walls). We can therefore conclude that a full evaluation of these fundamental factors is essential. To guarantee clear, repeatable results from products based on yeast cell walls you have to consider the production process, the producer and the product characteristics in terms of both composition and structure.

Physiological capabilities of yeast extracts and cell walls

As mentioned, yeast extracts also play an important functional role in supporting young or stressed animals as well as being used as an appetite stimulant.
We’ll now take a look at the main uses of yeast-derived products.

MOS, MANNAN-OLIGOSACCHARIDES:

Mannan-oligosaccharides play an important role in maintaining intestinal well-being and counteracting intestinal tract disorders.
They bind to intestinal pathogens such as Salmonella, E.coli as well as Clostridia and their intestinal receptors.

In this way, they help to prevent bacterial colonisation, counteracting disorders that could lead to diarrhoea.

β-GLUCANS

Functional polysaccharides that act on the modulation of the non-specific immune response, delivering a positive influence on animal health and production.
Principally owing to the activation of phagocytes, which make it easier to overcome bacterial infections and increase the antibody titer after vaccinations. Owing to their molecular composition, yeast β-Glucans are known to be the most effective for immunomodulation.

NUCLEOTIDES

Nucleotides are considered semi-essential nutrients: rapid-growing, sick or stressed animals do not have a sufficient endogenous production capacity for all nucleotides necessary to promote cell growth.
The inclusion of nucleotides in feed has therefore been shown to have a significant impact on the growth and feed conversion of animals (especially in the early weeks of life) by boosting intestinal maturation and the immune system.

APPETITE STIMULANTS / PALATANTS

Yeast extracts are often used to increase the palatability of feed or functional products, including medicated products. This effect is guaranteed by the presence of nitrogen compounds, useful also with Maillard reaction products along with free amino acids and small peptides.

OHLY, list of AVAILABLE PRODUCTS

OHLY, part of the British ABF group, has a history dating back to 1836. It is now one of the leading producers of yeast derivatives and pays particular focus on continuous research into improving the quality and functionality of its solutions.
All Ohly products are derived from the finest quality baker’s yeast culture, Saccharomyces cerevisiae.

After having first collaborated in the food sector, Garzanti Specialties has now widened its synergy with Ohly into the animal feed and pet food sectors enhancing the market affinity of these products.

Yeast cell walls products

• Ohly-GO®WALL: Yeast cell walls (Saccharomyces cerevisiae) obtained by hydrolysis with the addition of exogenous enzymes, separated by centrifugation from the soluble and dried yeast extract.

The product therefore consists of a mix of (1,3)(1,6)-β-D-Glucans (27 ± 4%) and MOS (18 ± 4%). The two functional polysaccharides that make up the product have beneficial effects on animal health, also improving productivity and are particularly useful in periods of high stress.

FUNCTION: binds mycotoxins, supports the immune system and activates macrophages. It also binds to and limits the colonization of intestinal pathogens.

APPLICATION: 0.25 – 2 kg/ton

• Ohly-GO®MOS: Yeast cell walls (Saccharomyces cerevisiae) obtained by autolysis and then separated from the soluble extract, giving an MoS content of 31 ± 4% and (1.3) (1.6) –β-D-Glucans of 21 ± 4%.

FUNCTION:  It binds to intestinal pathogens such as Salmonella, E. coli and Clostridia spp, thus preventing their colonization of the intestinal tract.

APPLICATION: 0.5 – 2 kg/ton

• Ohly-GO®GLUCAN: β-Glucans semi-purified from yeast cell walls (Saccharomyces cerevisiae) autolysed by a treatment with sodium hydroxide and repeated filtering to precisely purify the (1,3) (1,6) β-D-Glucans (≥ 48%).

There is also an advanced version OHLY-GO®GLUCAN ADVANCED with a level of (1,3)(1,6) β-D-Glucans ≥ 60%.

FUNCTION: modulates non-specific immune responses and general health, activating macrophages to overcome bacterial infections and increasing the antibody titres after vaccination. Perfect for use in periods of high stress. The (1,3) (1,6) β-D-Glucans also have the ability to bind some mycotoxins, such as zearalenone and ochratoxin.

APPLICATION: 0.05 – 0.25 kg/ton

Yeast extracts and appetite stimulants (palatant)

• Ohly-GO®NUCLEO: An enzymatically, hydrolysed yeast extract (derived from Saccharomyces cerevisiae).

It is a complete source of Nucleotides (CMP, GMP, IMP and UMP).

FUNCTION: their use improves the feed conversion ratio and performance of the animals.
Nucleotides are in fact semi-essential nutrients whose availability can be a limiting factor for growth due to an inability to produce them through biosynthesis especially in certain situations:
– in the juvenile phases where cells are rapidly dividing;
– in specific cellular tissues such as cells of the innate immune system (an important aspect for shrimp) and in cells of the gastro-intestinal tract;
– in stressed or sick animals.

By supplying nucleotides the energy requirement of the animal is reduced allowing it to better bear the stresses and be more resistant to attack by pathogens.

APPLICATION: 1 kg/ton

• Ohly-GO® KTD: A yeast extract (Saccharomyces cerevisiae) which adds a meaty taste and toasted notes.

It is a rich source of nutritional nitrogen compounds such as amino acids, amines, small peptides and nucleosides. With an intense roasted meat flavour, it is produced from autolysed yeast and glucose extracts followed by the Maillard’s reaction.

FUNCTION: improves the palatability of feed, masking any undesirable flavours.

APPLICATION: 0.2-1%, and up to 20% in premixtures.

• Ohly-GO® MEATY: A yeast extract derived from Saccharomyces cerevisiae providing meaty flavours.

It’s a rich source of appetizing nitrogenous compounds such as Maillard reaction products, free amino acids (15%) and small peptides (33%).

FUNCTION: improves the palatability of feed, masking any unpleasant taste of functional feed additives and active ingredients in veterinary medicines.
Particularly suitable for carnivorous animals.

APPLICATION: 0.2-1%, and up to 20% in premixtures.

Per further informations, please contact:
– Alessandro Schienoni: alessandro.schienoni@garzantispecialties.it
– Marco Montagnani: marco.montagnani@garzantispecialties.it