When you feed a cow, you are really feeding the rumen microbes first. Fibre digestion depends on a stable population of fibre-digesting bacteria and fungi that attach to pasture and silage particles.
Live yeast (a living Saccharomyces cerevisiae product) can help these fibre-digesting microbes perform their role in three main ways.
1. It makes the rumen a friendlier place for fibre microbes
Fibre-digesting microbes are sensitive to rapid declines in rumen pH. When cows consume a large amount of starch or sugar in a single feed, rapidly fermenting microbes produce acids, and rumen pH can fall.
Live yeast may help stabilise rumen conditions by supporting microbes that consume oxygen and utilise lactic acid. This can help maintain a more stable pH and support the activity of cellulolytic microbes.
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 shifts 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
