Sulfur is an essential component of the ruminant animal’s diet. It is needed for formation of certain amino acids and the B-vitamins, thiamine and biotin. Sulfur is also used in some detoxification reactions to maintain normal functioning of body cells.

The 1996 NRC Nutrient Requirements of Beef Cattle recommends a sulfur concentration of 0.15%. Excess sulfur concentrations in the diet can reduce feed intake, decrease copper status, and can contribute to the formation of polioencephalmalacia (PEM), which is necrosis of the cerebrocotical region of the brain. An animal with PEM will often press its heads against the fence or stagger around in the pen and may look into the sky with its head thrown back over the shoulder. Although a deficiency of thiamine is considered the most common cause of PEM, recent research indicates excessive levels of sulfur could initiate the disease. The NRC (1980) recommends 0.4% as the maximum tolerable level of sulfur in beef cattle diets.

Sulfur Sources
Feedstuffs—Feedstuffs with high levels of crude protein are usually high in sulfur and generally contain more than the daily requirement. Forages usually contain between 0.l% and 0.3% sulfur. With the increasing availability of byproducts from wet and dry milling industries consideration must be given to the amount of sulfur contributed in the diet from these sources. Removal of starch and steeping increases sulfur concentration in some byproducts. Table 1 lists sulfur concentration of some common feedstuffs and byproducts.

Table 1

Ingredient	% Sulfur (DM Basis)
Corn	0.11
Alfalfa	Hay 0.28
Corn Silage	0.12
Brome Hay	0.20
Soybean Hulls	0.11
Wheat Midds	0.19
Soybean Meal	0.46
Cottonseed Meal	0.42
Dry Corn Gluten	Feed 0.16-0.30
Wet Corn Gluten	Feed 0.35-0.40
Dried Distiller Grains	0.44
Wet Distillers Grains	0.5-0.7
Molasses Cane	0.47
Steep Liquor	0.7-1.5

Water
Water must also be considered when evaluating sulfur sources in beef cattle diets. Research conducted by the Integrated Livestock Management Program at Colorado State University evaluated the effects of water sulfate concentrations on performance, water intake, and carcass characteristics of feedlot steers. Actual water sulfate concentrations evaluated were 134.1, 291.2, 582.6, 1219.2, and 2360.4 mg/l. Increasing water sulfate concentrations decreased average daily gains and water intake and depressed feed efficiency. Final weight, hot carcass weight, and dressing percentage were all reduced with increasing water sulfate concentrations. The authors concluded that a water sulfate concentration of greater than 583 mg/l, or 0.22% of the diet, decreased feedlot performance. Nutritional Implications High sulfur concentrations in the diets of beef cattle can reduce feed intake, performance, and copper status of beef cattle. Testing of feed and water is an important tool in determining sulfur status of beef cattle. When formulating diets, the sulfur level in both feedstuffs and water must be evaluated. Total sulfur concentrations of above 0.3% from both feed and water are not recommended and can lead to reduced performance and an increased rate of PEM. If high sulfur concentrations in the diets are unavoidable, copper status must also be considered. Excess sulfur in the diet will bind copper and make it unavailable for the animal. If diets contain higher sulfur concentration, additional copper should be included in the diet. Dietary copper status should be evaluated and level adjusted based on total sulfur intake.

 

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