When excessive amounts of grain and carbohydrates are fed to ruminants with inadequate fibre in the diet, ruminal acidosis can occur. Ruminal acidosis in cattle can be acute, subacute or chronic. During acute ruminal acidosis, the pH in the rumen drastically drops and remains low for an extended period of time up to a day. If left untreated, acute acidosis can develop into complete metabolic acidosis. Subacute ruminal acidosis (SARA) is regarded as by repeated spells of low rumen pH, but unlike the situation with acute acidosis, the pH recovers after each spell. These spells of low pH typically last for several hours. The long spells are of concern because they negatively affect fibre digestion.