Burping Can be Dangerous if you are a Ruminant: Issues with High Sulfur Diets

Rumen microorganisms and the host ruminant animal require many macro and micro minerals for normal growth and development. Among these minerals, sulfur is a necessary component of the amino acids cystine and methionine that are building blocks of proteins. In ruminants, many inorganic forms of sulfur (e.g. potassium sulfate and calcium sulfate) can be used because sulfate is reduced in the rumen to sulfide by a group of bacteria referred to as the sulfur reducing bacteria and subsequently incorporated into microbial protein. However, excess production of sulfides in the rumen may be detrimental because high levels can cause polioencephalomalacia (PEM) (Lowe et al., 1996; Gould et al., 1991; McAllister et al., 1992). Polioencephalomalacia is a disease condition characterized by necrosis of the cerebrocortical region of the brain. A thiamine deficiency has been the most common cause of PEM in ruminants. Excess sulfur or sulfate in feed or water has been the second most reported condition associated with PEM. Consumption of excess lead (Christian and Tryphonas, 1971) and water deprivation (Sullivan, 1985) can result in the disease in some instances. High sulfur diets was the topic of a recent symposium at the 2008 ASAS Midwestern Section Meetings (http://ars.sdstate.edu/extbeef/). The objective of this paper is to review the relationships between the intake of high sulfur and PEM, and to discuss potential methods for control.