Research & Insights
Brewer's Yeast in Broiler Starter Feed: What the Trials Show
Published
Trials in broiler chickens indicate that yeast products improve weight gain and feed conversion without raising feed intake. A 2026 meta-analysis of 41 controlled studies reports 72.8 g more body weight gain and a feed conversion ratio improved by 0.055, along with taller intestinal villi. Dried brewer's yeast is one such ingredient.
Why do formulators look closely at the starter phase?
Several of the clearest signals in yeast trials appear early. Ahiwe et al. (2020) fed autolyzed whole yeast and yeast cell wall at 0.5 to 2.0 g/kg across starter, grower and finisher diets. Small intestine weight was heavier on days 10 and 24 for birds on the higher levels. Body weight gain and feed conversion improved on days 10, 24 and 35 at 1.0 to 2.0 g/kg.
Zhang et al. (2005) reported a related pattern. Cell wall at 0.3% lowered the feed to gain ratio from 0 to 3 weeks, and whole yeast at 0.5% lowered it at 4 to 5 weeks. Both raised body weight gain over the full 0 to 5 weeks.
What mechanism could explain the response?
The meta-analysis by Alagbe et al. (2026) found no significant change in feed intake (mean difference 3.57 g; 95% CI -17.6 to 24.7). The authors read this as a sign that the growth response comes mainly from better nutrient use.
Individual trials point the same way. Ahiwe et al. reported better ileal protein digestibility on day 24 with whole yeast at 2.0 g/kg, and higher trypsin and chymotrypsin activity at 1.5 to 2.0 g/kg on days 10 and 24. In Zhang et al., whole yeast and cell wall increased ileal villus height and the villus to crypt ratio, and Alagbe et al. reported taller villi across the pooled studies. Cell wall components such as mannan and beta-glucan are among the candidate explanations, as discussed in our comparison of yeast cell wall and brewers dried yeast.
What do the trials report, study by study?
| Study | Birds and duration | Material and inclusion | Reported result |
|---|---|---|---|
| Alagbe et al. (2026), meta-analysis | 41 controlled broiler studies | Yeast and yeast-derived products, mixed types and doses | Body weight gain +72.8 g (95% CI 58.2 to 87.4); FCR improved by 0.055 (0.045 to 0.065); feed intake unchanged; taller villi (mean difference 89.7) |
| Zhang et al. (2005) | 240 male broilers, 0 to 5 weeks | Whole yeast 0.5%; yeast extract 0.3%; cell wall 0.3% | Whole yeast and cell wall raised gain over 0 to 5 weeks; taller ileal villi |
| Ahiwe et al. (2020) | Broilers to day 35, six replicates of nine birds | Autolyzed whole yeast or cell wall, 0.5 to 2.0 g/kg | Gain and FCR improved at 1.0 to 2.0 g/kg on days 10, 24 and 35; better carcass and breast yield, mostly at 2 g/kg |
| Ergül (1988), cited by Feedipedia | Broilers | Dried yeast replacing fish meal, up to 9.3% of the diet | No differences in growth or feed efficiency |
These studies tested different materials. The meta-analysis pools several yeast product types, Ahiwe et al. used an autolyzed whole yeast, and Zhang et al. used whole yeast alongside separated fractions. A drum-dried whole yeast is closest to the whole yeast arms, and each product still needs its own trial.
What inclusion rate should a formulator test in a starter diet?
Alagbe et al. identified dose as a significant moderator of the response, so a single-level trial says little. Feedipedia gives 2 to 5% as the usual poultry range for brewers yeast, while the low-level studies above worked at 0.05 to 0.5%. A stepped ladder from 0.5 to 2% covers the ground between them.
| Inclusion | kg per tonne of feed | Crude protein added (points, at 40%) | Lysine added (g/kg diet, at 30.5 g/kg) |
|---|---|---|---|
| 0.5% | 5 | 0.20 | 0.15 |
| 1% | 10 | 0.40 | 0.31 |
| 2% | 20 | 0.80 | 0.61 |
The protein figures use the 40% lower end of the TBESBY specification range. These are gross supply values. Rebalance digestible amino acids from your own matrix at each step.
How should a starter trial be set up?
Keep one base diet and change only the yeast level, rebalancing to equal digestible amino acids and energy. The design used by Ahiwe et al. is a workable template: six replicates per treatment, with measurements on days 10, 24 and 35.
Record feed intake alongside gain, since the published response is expected in efficiency. If gut morphology is part of the question, sample ileal villus height and crypt depth at the same time points as performance.
What is the TBESBY specification?
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 plan a trial or compare this specification with your current ingredient, request a spec and CoA. See our page on livestock and poultry applications. Related reading: brewer's yeast for poultry and how to read a brewer's yeast CoA.
Frequently asked questions
How much brewer's yeast is used in broiler starter feed?
Feedipedia reports typical poultry use at 2 to 5% of the diet, and published trials have tested whole yeast from 0.05 to 0.5% as a functional inclusion. Test steps in your own base diet.
Does yeast change feed intake in broilers?
The 2026 meta-analysis of 41 studies found no significant effect on feed intake, which suggests the growth response comes from better nutrient use.
Can brewer's yeast replace fish meal in broiler diets?
One early trial replaced fish meal with dried yeast at up to 9.3% of the diet with no difference in growth or feed efficiency. Confirm in your own formula and rebalance amino acids.
Sources
Alagbe, E.O., Adeola, O. and Aderibigbe, A.S. (2026). Efficacy of yeast and yeast-derived products on growth performance and intestinal morphology of broiler chickens: a meta-analysis. Poultry Science 105(11):107513. DOI: 10.1016/j.psj.2026.107513
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
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
Feedipedia. Brewers yeast, poultry section, citing Ergül, M. (1988), Landbauforschung Völkenrode 38(3):211-219. feedipedia.org/Node/72