A dairy cow is, functionally, a fermentation vessel with legs: her productivity rises and falls with the stability of the microbial fermentation in her rumen. Live yeast earned its place in production nutrition by supporting exactly that stability. The yeast itself doesn't colonise permanently — fed daily, it works passing through, scavenging oxygen that would inhibit the strictly anaerobic fibre-digesting bacteria and moderating the conditions that let lactate-producing organisms tip the rumen towards acidity.
Where the evidence sits
Live yeast is unusual among our actives in how much of its evidence comes from production settings: decades of feeding trials in dairy and beef systems, reflected in the fact that specific yeast strains hold formal authorisations as zootechnical feed additives — a regulatory category that requires demonstrated effect. The recurring findings across that literature: support for fibre digestion, rumen pH stability, and feed efficiency, with the clearest value in high-demand windows — transition and early lactation in dairy cows, ration changes, heat stress, and intensive finishing in beef.
This is also the active that best illustrates our trial-to-supply model: its benefits are measurable in data farms already collect, so an on-farm evaluation can precede herd-wide adoption.
Horses: the hindgut parallel
The horse ferments fibre in the caecum and colon rather than a rumen, but the microbial logic rhymes. Live yeast is used in equine nutrition to support hindgut stability — particularly for horses on significant hard-feed rations, in work, travelling, or moving between forages, where the fermenting community is most easily unsettled.
A live active, handled accordingly
Like probiotics, live yeast is dosed in colony-forming units and is only useful alive. Strain identity, guaranteed viable count to end of shelf life, and processing that protects viability — including the heat of pelleting, which demands protected forms — are the specification. Our manufacturing treats viability as a release criterion, not an aspiration.
Frequently asked questions
What does live yeast do for dairy cows?
Fed daily, live yeast helps stabilise rumen fermentation — supporting the fibre-digesting microbes, steadier rumen pH and feed efficiency — with its clearest value around transition, early lactation and ration change. It is one of the most extensively trialled additives in ruminant nutrition.
Is live yeast the same as brewer's yeast?
No. Brewer's yeast in feeds is typically inactivated — a protein and B-vitamin source. Live yeast products contain viable organisms at a guaranteed count, which is what the rumen-function evidence is built on. The label should say which one you're buying.
Can horses have live yeast?
Yes — live yeast is used in equine feeds and supplements to support hindgut stability, particularly for stabled, hard-fed and travelling horses. Introduce feed changes gradually as ever.