What does sulfur do for cattle?

Answer 1

(Taken from Chapter 8: Feeding Beef Cattle, p. 273 of Beef Cattle Science by M.E. Ensminger and R.C. Perry):

Sulfur is one macromineral that is important for the health of cattle. Macrominerals include, besides Sulfur, Calcium, Phosphorus, Salt (NaCl), Magnesium, and Potassium. Sulfur is a component of protein, some vitamins, and several important hormones. The common sulfur-containing amino acids are methionine, cysteine, and cystine. Also, the following amino acid derivatives contain sulphur: cystathionine, taurine, and cysteic acid. Methionine is a key amino acid because all other sulfur compounds, except B-vitamins thiamin and biotin, can be synthesized from methionine.

All feeds contain some sulfur, but the amount usually depends on the protein content of the feed--generally speaking, the higher the protein count, the higher the sulfur content. Availability of the sulfur in the feed to microbial reduction in the rumen may be as much of a concern as the actual amount that is present.

(From Table 8-5 of Beef Cattle Science, Chapter 8, p. 274-5):

Body functions that involve sulfur include protein synthesis and metabolism, fat and carbohydrate metabolism, blood clotting, endocrine function, and intra- and extra-cellular fluid acid-base balance. Sulfur has both structural and metabolic functions; it is found in virtually every tissue and organ of the body. Muscle has a fairly constant nitrogen to sulfur ratio of 15:3:1. The total body content of sulfur is approximately 0.15%.

Deficiency of sulfur include such symptoms as depressed appetite, weight loss, weakness, excessive salivation, watery eyes, dullness, emaciation, and death. A lack of sulfur also results in a microbial population that does not utilize lactate. Usually deficiencies of sulfur are reported in cattle that are fed high-grain rations and supplemented with non-protein nitrogen.

Toxicity level of sulfur, according to the NRC (Nutritional Research Center) is 0.40% of the ration dry matter. Sulfur toxicity is characterized by restlessness, diarrhea, muscular twitching, dyspnea, and in prolonged cases of inactivity followed by death.

A ration (dry matter) should have a sulfur level of a minimum of 0.15% and a maximum of 0.4%. If the ration is higher or lower than these numbers, toxicity or deficiency levels will develop, respectively.

Some practical sources of this mineral include feeds that are high in protein (these usually high in sulfur as well). The microbial population of the rumen has the ability to convert inorganic sulfur into organic sulfuric compounds that can be used by the animal. So, either organic or inorganic sulfur can be used by cattle. Most feedstuffs provided to beef cattle contain sufficient sulfur to meet their needs.

Note that copper requirements are increased by both sulfur and molybdenum. Selenium can also be a replacement for sulfur in some organic compounds.