Rumen Acidosis

NWDC is in the process of updating this fact sheet. 

Other names: Grain overload, Corn toxicity, Lactic acidosis, Carbohydrate engorgement


Rumen acidosis occurs when wild or domestic ruminants (deer, elk, moose, cattle, sheep etc.) ingest large quantities of readily digestible and highly fermentable carbohydrates such as grain. Corn, wheat, and barley are most commonly responsible for rumen acidosis, though apples, grapes, bread, and sugar beets can also cause this disease. 


Rumen acidosis occurs in wild deer, elk, and moose when they suddenly ingest large quantities of grain, usually corn. Though it can result in rapid death, it does not currently have a significant impact on wild ruminant populations. However, in restored or endangered populations it can be a serious source of mortality. Its affect on local populations may be underestimated because of the inability to quantify the animals that survive, but have shortened life spans because of the effects of this disease.

Species Affected

Rumen acidosis can occur in any ruminant. This disease is most commonly observed in deer, elk, moose, and domestic cattle. Bison seem less susceptible, but can still suffer from grain overload. 


This disease can occur anywhere in the world where wild or domestic ruminants are suddenly introduced to large quantities of carbohydrates.


Clinical Signs

Within 24 to 48 hours of ingesting large quantities of carbohydrates, the animal will stop eating and may be staggering, unable to rise, or standing quietly. Affected animals often have an enlarged rumen and diarrhea. The most severely affected will die within 24 to 72 hours. Since death is sudden, animals are usually in good body condition. At necropsy, the rumen is often full of corn or other grain and there may be dark red erosions in the lining of the abomasum.


Rumen acidosis can usually be diagnosed when ruminants in good body condition are found dead with large quantities of grain in their stomachs. Laboratory analysis of the rumen microflora can be used to support the diagnosis. The pH of the rumen begins to rise after death, so normal values at necropsy do not rule out the disease.


There is no treatment for rumen acidosis in wild ruminants because they are typically found dead. There is also no treatment for those who survived but have a permanently damaged rumen lining.


Supplemental feeding of wild ruminants is often the cause of rumen acidosis. Restrictions on supplemental feeding may help prevent the occurrence of this disease. Hunters should be discouraged from using bait and farmers should make sure wild ruminants do not have access to grain stores.