When you feed a cow, you are really feeding the rumen microbes first. Fibre digestion depends on a steady population of fibre-eating bacteria and fungi that stick to pasture and silage.
Live yeast (a living Saccharomyces cerevisiae product) can help those fibre-digesters do their job in three main ways.
1. It makes the rumen a friendlier place for fibre microbes
Fibre-digesting microbes don’t like it when rumen pH drops quickly. When cows get a lot of starch or sugars in one feed, fast-fermenting microbes produce acids, and pH can fall. Live yeast can help stabilise rumen conditions by supporting microbes that use up oxygen and lactic acid, which helps keep pH steadier and keeps cellulolytic microbes working.
A large meta-analysis across many ruminant studies found yeast supplementation was linked with changes in rumen fermentation that fit a more stable rumen environment.
2. It helps the right microbes colonise fibre faster
For fibre to be digested well, microbes need to attach to plant particles quickly after the cow eats. One study in dairy cows found live yeast increased colonisation of plant material by fibrolytic bacteria and fungi, and this was linked with higher fibre degradation in the rumen.
3. It supports consistency during pressure points
In NZ systems, fibre digestion can be shaky when pasture is lush and low in effective fibre, when more palm kernel or grain comes in, or when silage type changes. Responses vary between farms, but live yeast is often used to help keep rumen function more even through these shifts.
How does this help the cow?
Fibre is where a lot of the cow’s energy comes from in pasture-based systems. If more neutral detergent fibre (NDF) is broken down in the rumen, the cow can pull more energy out of the same mouthful. That can support milk production and body condition, as long as the diet still has enough effective fibre.
What does this look like on-farm?
More cud chewing, a more consistent manure texture and fewer swings in appetite. You may also see steadier intakes across the day.
How do I get the best out of live yeast?
Feed it every day at the Agvance label rate, keep it dry and cool, and make diet changes gradually. Keep the basics right: fibre quality, chop length and a sensible starch load.
Talk to your local Agvance Consultant to find the best live yeast supplement for your herd.
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Sources
https://doi.org/10.3168/jds.2008-1414
https://doi.org/10.1111/jam.13005
