Total Dissolved Solids, Sulfates Pose Risk In Livestock Drinking Water

 BROOKINGS, S.D. -- Ongoing research by South Dakota State University scientists can help producers know when poor quality water spells danger for livestock.

Drought makes poor quality water worse as evaporation and lack of recharge concentrates salts. Drought can also force producers to water their livestock from poor quality sources they would otherwise avoid.

SDSU Extension Beef Specialist Trey Patterson, SDSU Extension Veterinarian Bill Epperson and SDSU range science professor Pat Johnson said sulfates appear to be the salt that causes the most problems in South Dakota.

Epperson said the physical signs seen in animals are those of polioencephalomalacia ("polio") and include lethargy, anorexia, blindness, muscle tremor, exaggerated response to sound or touch, incoordination, staggering, weakness, and eventually convulsions and inability to get up.

If animals exhibit signs of polio or die, producers should contact their veterinarian for assistance. Cattle polio can be successfully treated by providing good water, thiamine injections and anti-inflammatories.

Most county Extension offices in South Dakota have conductivity meters and Extension staff will do a simple screening test to assess water quality free of charge. As the amount of salt in the water (expressed as Total Dissolved Solids or TDS) goes up, electrical conductivity goes up. Preliminary observations from SDSU research suggest that at higher levels of TDS, the majority of the salt is sodium sulfate. At moderate levels of TDS, the proportion from sulfate is variable. At low levels of TDS, sulfate levels should be low enough so no problems occur.

If TDS levels are moderately high (3,000 parts per million or greater), samples should be submitted to a certified laboratory for a sulfate test.

Nitrate levels in water can be elevated, although this does not appear to be a large concern in South Dakota.  A "Livestock Suitability Test" from the laboratory will report nitrates along with sulfates and other salts.  The maximum safe levels for nitrates in water are around 400 parts per million, but this may be reduced if nitrates are present in the diet. Selenium in water is a concern in some areas.  A selenium test can be requested if problems are suspected.  Selenium levels in water above 0.05 parts per million may be dangerous.

 When comparing results from water analysis to recommendations, it is important that the units are the same.  It is not uncommon for sulfates and nitrates to be reported as sulfate-sulfur and nitrate-nitrogen, respectively.  Sulfates are 33.3 percent sulfur and nitrates are 22.6 percent nitrogen.  The values described here are for sulfates and nitrates, not sulfur and nitrogen.

Here's what SDSU research is revealing about Total Dissolved Solids:

Under 2,000 parts per million: Safe. Levels greater than 1,000 may have some laxative effect and may reduce availability of trace minerals.

2,000 to 3,000 parts per million: Generally safe. May reduce performance, should not affect health. Monitor water as weather gets hot.

3,000 to 5,000 parts per million: Marginal. May reduce performance and affect health. Test water for sulfates and monitor.

5,000 to 8,000 parts per million: Poor water. Performance and health depression expected in times of high temperatures. Test for sulfates. Use for low-producing stock.

8,000 to 10,000 parts per million: Dangerous. Performance and health depression expected. Do not use for pregnant or lactating cattle. Sulfates likely to be high.

Over 10,000 parts per million: Dangerous. Not suitable for livestock. Do not use.

 SDSU water quality research also provides some guidelines for producers dealing with high levels of sulfate in livestock drinking water.

Under 500 parts per million: Safe.

500 to 1,000 parts per million: Generally safe. A mild laxative effect may be seen. Trace mineral availability may begin to be reduced. This level has decreased performance in feedlot cattle.

1,000 to 2,500 parts per million: Marginal. Sporadic cases of polio may be seen in confined cattle. Performance may be affected.

2,500 to 4,000 parts per million: Poor water. Sporadic cases of polio are probable, especially in confined cattle. Performance of grazing cattle may be affected.

Over 4,000 parts per million: Dangerous. Health problems expected.

More about responding to drought can be found at a South Dakota State University Extension Web site, http://sdces.sdstate.edu/drought/. More about livestock drought issues is at an SDSU Department of Animal and Range Science Web site, http://ars.sdstate.edu/extbeef/Drought_Management.htm.
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Contacts: Trey Patterson, (605) 394-2236; Pat Johnson, (605) 394-2236; Bill Epperson, (605) 688-6589
** For links to other sites showcasing SDSU's work in teaching, research, and Extension, visit http://sdces.sdstate.edu.

Lance Nixon, Editor
AgBio Communications Unit
South Dakota State University
ACC, Box 2231, Rm 200
Brookings, SD 57007
Telephone: (605) 688-4653
Lance_Nixon@sdstate.edu