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cows eating grass

Using the Sulfur Calculator

Tips for using the sulfur calculator:

  • Enter the weight in pounds of the type of cattle under consideration
  • Indicate lactating or non-lactating.
  • Enter the sulfate concentration of the water source in ppm (same as mg/L). Leave the entry as zero, if the number is unknown.
  • If the total mixed ration has been analyzed, enter the identification/name of the ration.
  • In the space "% sulfur in feed" enter the % sulfur as dry matter (DM) measured by laboratory analysis. This is usually expressed as % sulfur, but if the data is given as % sulfate, divide the value by 3.
  • In the space under "Percent of total feed/forage intake" enter the number 100, since this is the total ration.
  • If separate feed/forage components are analysed, enter the names of up to five components in the spaces under feedstuff name. In the spaces under "% sulfur in feed" enter the % sulfur as dry matter (DM) measured by laboratory analysis for each component. These are usually expressed as % sulfur, but if the data are given as % sulfate, divide each value by 3. In the spaces under "Percent of total feed/forage intake" enter the % of the DMI each component is estimated to represent. The sum of these percents must = 100. See the note below on behaviour and feed/forage selection.
  • After the spaces are filled, click on the calculate button.

Interpreting the Calculation

When the calculation is done, the contribution of sulfur from the water is shown for the water intake levels at different ambient temperature conditions. This contribution is expressed as % sulfur of dry matter intake (DMI).

The information is summarized as animal information, intake information, and calculated values at several ambient temperature assumptions. The calculated values shown are:

  1. Estimated water intake in liters
  2. Grams of sulfur consumed in water
  3. Percent S as dry matter contributed by sulfur in water
  4. Percent sulfur in all feed or forage, and, finally
  5. Estimated total sulfur concentration taking all sources into account.

This is the value to be compared to the maximum tolerable sulfur concentration, estimated at 0.4% DM (National Research Council, Nutrient Requirements of Beef Cattle, Seventh Revised Edition, pg 61, 1996). However, the actual risk of polioencephalomalacia depends on the state of ruminal microbial adaptation and other factors in addition to total sulfur intake. (For a more complete discussion of these concepts, refer to Gould, DH: Update on sulfur-associated polioencephalomalacia, Veterinary Clinics of North America: Food Animal Practice, Toxicology. 16:481-496, 2000)

When animals are free to select a particular feed ingredient or forage component, behavior becomes an important variable. Therefore, it is useful to calculate TSC for the animals that might have risky behaviors resulting in an exaggerated consumption of a particular diet ingredient. If the sulfur content of individual dietary components is analyzed separately it is possible to look for specific ingredients that, if selectively consumed by animals manifesting particular eating behaviors, could increase the TSC.

Contact Us:

Fort Collins Veterinary Diagnostic Laboratory
300 West Drake Road
Fort Collins, CO 80526

(970) 297-1281

(970) 297-0320
Hours: M-F 8 a.m. - 5 p.m.
USPS Mailing Address:
200 West Lake Street
1644 Campus Delivery
Fort Collins, CO 80523-1644

FedEx/UPS Shipping Address:
300 West Drake Road
Fort Collins, CO 80526