Promune: Yeast Protein as a Soybean Meal Replacement

Soybean meal is typically one of the largest costs in poultry diets after energy sources, yet its price can be difficult to predict. Prices are influenced by weather conditions in major soybean-producing countries such as Brazil, freight costs, and export policies in countries most producers will never even visit.

So the question is not whether soybean meal is good. It is whether every kilogram of it is doing work that could not be done by something cheaper, more stable, or simply less of.

3A Promune is a high-protein yeast product built on a selected strain of Saccharomyces cerevisiae, grown on wheat bran and fermented under controlled conditions, then dried in its original fermentation medium. That last detail matters more than it sounds: drying in the fermentation medium concentrates the protein while keeping the yeast components that support immune function intact, rather than stripping them out.

The result is a protein source, not a supplement in the usual sense. It is formulated into finished feed as a replacement for part of the soybean meal, for poultry, ruminants and swine

This is the part worth slowing down on, because it is where the commercial case sits.

3A Promune is formulated so that 25 kg per tonne of finished feed replaces 35 kg per tonne of soybean meal. Ten kilograms less material, per tonne, doing the same protein job.

Two things explain the ratio, and they are worth separating because they behave differently in the field.

The arithmetic is straightforward. At 60%+ protein against roughly 43%, you need materially less product to deliver the same protein contribution. Energy is slightly higher too, so the substitution does not force a compensating change elsewhere in the formulation.

Note the price line in the table above: comparable, not cheaper. That is the point. When the cost per kilogram is similar and you need 29% less material to do the same job, the saving is simply the material you no longer buy.

There is a second-order benefit here that nutritionists notice before purchasing managers do: those ten freed kilograms are formulation space. In a tight starter diet, ten kilograms per tonne is room for energy, or for a functional ingredient that would not otherwise fit.

Soybean meal brings passengers. Trypsin inhibitors, lectins and indigestible oligosaccharides such as stachyose and raffinose all travel with it. Processing reduces them; it does not eliminate them. In mature animals with settled digestive systems this is a minor tax. In young birds, and in any animal already under stress, it is not minor at all: the same anti-nutritional load costs more when digestive capacity is already stretched.

Yeast protein does not carry those passengers. This is the mechanistic reason the observed advantage tends to be largest exactly where the bird is under the most pressure, which is what the trial below shows.

An experiment was run to evaluate dietary supplementation with high-protein yeast in heat-stressed broilers. The design is worth reading closely, because it determines how the results should be interpreted.

128 Cobb 400 broilers were used. Ambient temperature was held at 32 to 34 degrees Celsius for the duration, and at 21 days the birds were additionally challenged with an oral dose of Salmonella. This is not a comfortable-conditions trial. It is a deliberately hard one.

Body weight at day 35 was significantly improved, with the difference reaching statistical significance at both 21 and 35 days. FCR fell by 0.219 points. On the Salmonella challenge, counts rose in both groups through the first week and then diverged: by 14 days after inoculation the supplemented group was markedly lower, indicating those birds cleared the challenge faster. Worth noting that the control group already carried a higher count before inoculation.

An FCR improvement of 21.9 points is a very large number. Large enough that anyone who has spent time in broiler production will, correctly, raise an eyebrow. So here is the context that makes it credible rather than suspicious.

These birds spent the whole trial at 32 to 34 degrees and were then deliberately infected. Under that load, the control group was not performing normally. Heat stress alone reduces feed intake, damages gut barrier integrity and diverts energy away from growth; a Salmonella challenge on top of that compounds all three. The gap between groups is wide because the control had a long way to fall, not only because the supplemented group climbed.

The practical translation: in a well-ventilated house at comfortable temperature with clean birds, do not expect 22 FCR points. Expect considerably less. What this trial demonstrates is not a universal performance number, it is where the product earns its place — when conditions are against the bird.

That happens to describe a great deal of the world. Broiler production in South Asia, the Middle East, Africa and the southern United States runs into 32-degree ambient conditions as a matter of routine, not as an experimental treatment. For those producers this trial is not an edge case; it is a normal season.

Three situations where the argument is strongest:

• Hot climates and summer periods. Heat stress reduces intake and compromises the gut. A protein source that is easier to digest and carries no anti-nutritional load asks less of an animal that has less to give.
• Starter diets. Young birds have the least digestive capacity and the most to lose from anti-nutritional factors. This is where replacing part of the soybean fraction tends to show up first.
• Antibiotic-free production. In antibiotic-free poultry systems the gut has to do more work unaided. Support for immune function through the diet is part of how that gap gets covered, alongside water-line tools such as Ecopol.

And one where it is not the answer: if your problem is a specific disease, this is a nutritional product and belongs in the feed programme, not in the treatment plan. It supports immune function; it does not treat infection, and nothing here replaces veterinary diagnosis or sound biosecurity.

Inclusion: 25 kg per tonne of finished feed, formulated to replace 35 kg per tonne of soybean meal.

Packaging and storage: 25 kg bags. Store cool, dry and dark, away from direct sunlight, below 30 °C. Use within three years of production date.

Because it is formulated into finished feed rather than dosed per animal, the change happens once at the mill and then runs on its own. There is no on-farm labour attached to it, which matters when the alternative interventions all require someone to do something daily.

The case for high-protein yeast is not that soybean meal is bad. It is that a meaningful share of it can be replaced by less material that carries no anti-nutritional load, at a protein density that frees up formulation space, from a supply chain that does not move with the soybean market.

Under challenge conditions, the measured difference was substantial: 223 g more body weight at day 35, 0.219 points better FCR, and faster clearance of a Salmonella challenge. Under easier conditions, expect a smaller gap. Either way, 3A Promune is doing the work in the part of the ration that is hardest to plan around.

A selected strain of Saccharomyces cerevisiae yeast, grown on wheat bran and fermented under controlled conditions, then dried in its original fermentation medium. The finished product carries over 60% crude protein, plus wheat gluten.

It is formulated so that 25 kg per tonne of finished feed replaces 35 kg per tonne of soybean meal. Work with your nutritionist on the full formulation, since the freed space and the energy contribution both affect the rest of the diet.

Two reasons. It is more protein-dense, so less material is needed. And it carries none of the anti-nutritional factors that travel with soybean meal, such as trypsin inhibitors, lectins and indigestible oligosaccharides. The difference is largest in young animals and in animals under stress, where digestive capacity is already limited.

It is a nutritional product, not a treatment. In a challenge trial, broilers on the supplemented diet showed a lower Salmonella count in excreta by 14 days after inoculation than control birds, which suggests the supported birds cleared the challenge faster.

Yes. It is formulated as a protein source for poultry, ruminants and swine. The broiler data above is the most completely documented, but the nutritional rationale, protein density and the absence of anti-nutritional factors, applies across species.

Yes. It contains no antibiotics and no synthetic growth promoters, and it is used as a feed material rather than as a medication. In antibiotic-free systems, nutritional support for gut and immune function does more work than it does in conventional systems, because there is no antibiotic cover underneath it.