What is Subclinical Rumen Acidosis?
Subclinical rumen acidosis (also called subacute rumen acidosis or SARA) occurs when the pH (acidity) of the cow’s rumen drops below 5.8. When the rumen microbes ferment feed, they produce acids. If this acid builds up, rumen pH drops and inhibits microbial growth. At low rumen pH, the concentration of hydrogen ions outside the rumen microbes goes up, and these hydrogen ions leak inside the microbes. In order to maintain near neutral pH within their cells, the microbes then must expend additional energy to get rid of the hydrogen ions. This process results in less energy available for the microbes to use to grow. Those microbes that ferment fiber are especially affected. Intake declines and becomes variable, fiber digestibility is reduced, and rumen microbial protein production is limited by rumen acidosis. The result is that milk and milkfat production also often are reduced. Often herd owners and their nutritionists assume that there is no acidosis problem unless cows go off-feed, mi
