Research & Insights
MOS and Beta-Glucans in Whole Brewer's Yeast: What the Cell Wall Contributes
Published
Whole dried brewer's yeast carries the cell wall from which commercial MOS and beta-glucan products are made. Published compositions suggest about 3.6 to 4.5% mannan and 5.2 to 6.4% beta-glucan as fed. At 2% inclusion, that is roughly 0.7 to 0.9 g/kg mannan and 1.0 to 1.3 g/kg beta-glucan in the diet.
What are MOS and beta-glucans in a yeast ingredient?
Mannan-oligosaccharides (MOS) and beta-glucans are carbohydrate fractions of the Saccharomyces cerevisiae cell wall. Commercial MOS products are mostly derived from yeast cell walls, according to Teng and Kim (2018). Mannoproteins form the outer layer of the wall, and beta-glucans give it structure.
Reported proportions vary with method and growth conditions. Avramia and Amariei (2021) describe a wall that is 50 to 55% beta-1,3-glucan and up to 15% beta-1,6-glucan, with mannoproteins near 40%. Patterson et al. (2023) report the wall at 26 to 32% of the dry weight of intact yeast, and S. cerevisiae cell wall products averaging 22.28% glucan and 15.49% mannan.
Those two sets of numbers describe different things. The first is the polysaccharide structure of the wall. The second is the analysis of cell wall products, which also carry protein, 32.53% crude protein on average in the Patterson review.
How are MOS and beta-glucans thought to act in the gut?
The literature describes three main routes. MOS can bind bacteria that carry type-1 fimbriae, including E. coli and Salmonella, which is thought to reduce their attachment to the gut wall (Spring et al., 2015; Teng and Kim, 2018).
A second route runs through gut structure. Studies in broilers have associated MOS with longer villi, more goblet cells, greater mucin gene expression and higher Lactobacillus levels. A third is immune signalling: TLR2 and TLR4 may recognize MOS, while dectin-1 may be present on the macrophages and heterophils that respond to beta-glucan (Teng and Kim, 2018). Most of this mechanistic work used isolated fractions and cell wall products.
What do published trials report?
The summary covers broilers and turkeys, where the reviews we read give the most quantified outcomes.
| Study | Species | Material and level | Reported result |
|---|---|---|---|
| Hooge (2004), reported by Spring et al. (2015) | Broilers, 34 trials | Commercial MOS versus negative control | Body weight +1.95%; FCR -2.25%; mortality -21.78% (19 trials) |
| Hooge (2004), reported by Spring et al. (2015) | Turkeys, 23 to 27 trials | Commercial MOS versus negative control | Body weight +2.25%; FCR -1.62%; mortality -24.64% (16 trials) |
| Zhang et al. (2005) | Broilers, 0 to 5 weeks | Whole yeast 0.5%; cell wall 0.3% | Both raised body weight gain over 0 to 5 weeks; taller ileal villi and higher villus to crypt ratio |
| Ahiwe et al. (2020) | Broilers to day 35 | Autolyzed whole yeast or cell wall, 1.0 to 2.0 g/kg | Body weight gain and FCR improved on days 10, 24 and 35 |
| Studies cited by Teng and Kim (2018) | Broilers | MOS 0.1 to 0.4% | Lower cecal Salmonella at 0.4% under challenge; taller villi and more goblet cells at 0.1% |
Response varies with diet, challenge level and the material tested. Treat these figures as a starting range for your own trial.
How much mannan and beta-glucan does a whole yeast inclusion supply?
A spec sheet for whole brewer's yeast usually lists crude protein, moisture, ash, fat, fibre and amino acids, and leaves out mannan and beta-glucan. Published analyses allow a working estimate. Take the cell wall at 26 to 32% of dry matter, the glucan and mannan values above, and a product at 90% dry matter. The whole yeast then contains about 5.2 to 6.4% beta-glucan and 3.6 to 4.5% mannan as fed.
| Whole yeast inclusion | kg per tonne of feed | Beta-glucan supplied (g/kg diet) | Mannan supplied (g/kg diet) |
|---|---|---|---|
| 0.5% | 5 | 0.26 to 0.32 | 0.18 to 0.22 |
| 1% | 10 | 0.52 to 0.64 | 0.36 to 0.45 |
| 2% | 20 | 1.04 to 1.28 | 0.72 to 0.89 |
| 5% | 50 | 2.61 to 3.21 | 1.81 to 2.23 |
Two limits apply. The estimate uses literature averages, and the TBESBY specification does not state a beta-glucan or mannan value. It also describes quantity only. Fractions held inside an intact cell may be less accessible than those in a processed product, a point Patterson et al. raise when discussing solubility and enzymatic processing, so a gram of mannan from whole yeast should not be assumed to match a gram from a purified MOS. If a formula depends on the number, ask your supplier for an analysis.
When does whole yeast fit, and when does a purified fraction fit?
The two ingredients answer different formulation questions. Purified MOS and cell wall products go in at low levels, 0.1 to 0.5% in the broiler studies above, to deliver a targeted dose of the fraction.
Whole dried brewer's yeast is a protein ingredient first. It supplies crude protein and amino acids, and the cell wall comes with it. Feedipedia reports typical poultry use at 2 to 5% of the diet, which places the estimated mannan and beta-glucan supply in the lower rows of the table.
TBES supplies whole-cell dried brewer's yeast only. We do not sell MOS, beta-glucan or yeast cell wall products. Brewer's yeast is a co-product of brewing recovered for nutritional use, which suits EU and UK buyers who track circular sourcing.
What is the TBESBY specification for whole dried brewer's yeast?
TBESBY dried brewer's yeast is drum-dried, milled, screened and packed at our own facilities in Vietnam.
| Parameter | Specification |
|---|---|
| Crude protein | 40 to 46% |
| Moisture | Below 10% |
| Ash | Below 6% |
| Fat | Maximum 0.5% |
| Fibre | Maximum 1.5% |
| Lysine | 30.5 g/kg |
| Shelf life | 12 months |
| Packing | 25 kg bags; jumbo bags 600 to 1,200 kg |
| Registrations and certification | U.S. FDA registered; ISO 22000:2018; non-GMO |
To compare this specification with your current ingredient, request a spec and CoA. Applications by species are on our pages for livestock and poultry and pet food. Related reading: yeast cell wall versus brewers dried yeast and the brewer's yeast nutrient profile.
Frequently asked questions
Is brewer's yeast the same as MOS?
No. MOS is a fraction of the yeast cell wall. Whole brewer's yeast contains the complete cell, including protein and the cell wall from which MOS is derived.
How much beta-glucan is in whole brewer's yeast?
Literature averages suggest about 5.2 to 6.4% as fed at 90% dry matter. Actual content varies with strain, growth conditions and processing.
Does TBESBY sell MOS or beta-glucan?
No. TBESBY supplies whole-cell dried brewer's yeast. The cell wall fractions discussed here are part of the whole product.
Sources
Avramia, I. and Amariei, S. (2021). Spent Brewer's Yeast as a Source of Insoluble Beta-Glucans. International Journal of Molecular Sciences 22(2):825. DOI: 10.3390/ijms22020825
Patterson, R., Rogiewicz, A., Kiarie, E.G. and Slominski, B.A. (2023). Yeast derivatives as a source of bioactive components in animal nutrition: A brief review. Frontiers in Veterinary Science 9:1067383. DOI: 10.3389/fvets.2022.1067383
Spring, P., Wenk, C., Connolly, A. and Kiers, A. (2015). A review of 733 published trials on Bio-Mos, a mannan oligosaccharide, and Actigen, a second generation mannose rich fraction, on farm and companion animals. Journal of Applied Animal Nutrition 3:e8. DOI: 10.1017/jan.2015.6
Teng, P.Y. and Kim, W.K. (2018). Review: Roles of Prebiotics in Intestinal Ecosystem of Broilers. Frontiers in Veterinary Science 5:245. DOI: 10.3389/fvets.2018.00245
Zhang, A.W. et al. (2005). Effects of yeast (Saccharomyces cerevisiae) cell components on growth performance, meat quality, and ileal mucosa development of broiler chicks. Poultry Science 84(7):1015-1021. DOI: 10.1093/ps/84.7.1015
Ahiwe, E.U. et al. (2020). Influence of dietary supplementation of autolyzed whole yeast and yeast cell wall products on broiler chickens. Asian-Australasian Journal of Animal Sciences 33(4):579-587. DOI: 10.5713/ajas.19.0220
Feedipedia. Brewers yeast. INRAE, CIRAD, AFZ and FAO. feedipedia.org/Node/72