Sub-Acute Ruminal Acidosis (SARA) Risk Management

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December 4 2013


Sub-Acute Ruminal Acidosis (SARA) is usually caused by feeding cows a highly fermentable cereal-based concentrate (mainly starch) too quickly with little or no adaptation period.  High fermentation causes a rapid increase in volatile fatty acids (VFA) production in the rumen without an equal increase in their absorption. Consequently the acids accumulate, resulting in a decrease in rumen pH, below a threshold. Optimum rumen pH for fermentation in dairy cows is between 6.4 and 6.0. Anything below this will predispose dairy cows to SARA. Unadjusted feeding of high quantities of cereal-based diet, inadequate or lack of fibre in the diet of dairy cows, especially during the transition period will increase the risk of SARA. 

It is difficult to diagnose SARA but common symptoms include a reduction in feed intake, rumination (chewing cud), and milk fat content. Health issues resulting from SARA include liver abscess, scouring laminitis and displaced abomasum.

Strategies that will help to reduce the risk of SARA include the following.

  1. Maintain a diet with 25-30% fibre (NDF, neutral detergent fibre) with 70-80% of this coming from forage (fresh grass, hay, straw or silage). Adequate fibre helps to maintain a stable rumen pH by ensuring cows ruminate.
  2. Avoid rapid and sudden introduction of cows to high cereal-based concentrate diets. 
  3. Consider using rumen buffers and rumen modifiers to help maintain stable rumen pH.

For more information speak to your CopRice Nutritionist or check out the Dairy Australia Website.