Tolga AkayRuminant Nutrition

Live Rumen

A cross-section of the rumen responding to the diet. Move the controls to see the expected direction of change in fermentation, acid load, buffering and the 24-hour pH pattern.

Educational simulationThis visualization demonstrates expected directional relationships and is not a validated animal-level prediction model.

Why the rumen responds this way

More rapidly fermentable starch → faster acid production → lower simulated pH tendency and a shift towards propionate.
More physically effective fibre → more chewing and rumination → more saliva → better buffering tendency.
Large meals → larger post-feeding pH depression than the same feed eaten in many small meals.
High unsaturated fat can disturb fibre digestion and biohydrogenation, which is linked to milk fat depression (Bauman & Griinari, 2003).

What you can change

Dietary starch: Starch in total ration dry matter.
Forage NDF: NDF supplied by forages.
Physically effective fibre (peNDF): Fibre long enough to stimulate chewing and rumination.
Dry matter intake: Higher intake means more substrate fermented per day.
Starch fermentability
Unsaturated fat
Feeding pattern
Dietary buffer
Live yeast

Methodology & references

The simulation combines the inputs into two relative scores, “acid load” (starch × fermentability, intake, low forage NDF) and “buffering” (peNDF, forage NDF, buffer, live yeast), and applies a meal-response curve for each feeding. Directions follow the reviewed literature; the size of the effects is illustrative and is not a validated prediction for any cow or herd. Real rumen pH can only be known by measurement (e.g. boluses or rumenocentesis).

Plaizier, J.C., Krause, D.O., Gozho, G.N., McBride, B.W. (2008). Subacute ruminal acidosis in dairy cows: the physiological causes, incidence and consequences. The Veterinary Journal 176: 21–31.
Krause, K.M., Oetzel, G.R. (2006). Understanding and preventing subacute ruminal acidosis in dairy herds: a review. Animal Feed Science and Technology 126: 215–236.
Allen, M.S. (1997). Relationship between fermentation acid production in the rumen and the requirement for physically effective fiber. Journal of Dairy Science 80: 1447–1462.
Bauman, D.E., Griinari, J.M. (2003). Nutritional regulation of milk fat synthesis. Annual Review of Nutrition 23: 203–227.