By Murray Feist, M.Sc., PAg., Ruminant Nutrition Specialist
During the summer of 2017, water quality was severely and negatively impacted by high winds and temperature. Many surface water bodies were disabled and condemned due to elevated levels of electrical conductivity, total dissolved solids and sulfates.
- Electrical Conductivity: the ability of the water to conduct electricity and influenced by the amount and types of dissolved minerals and other particles in the water (McLean circa 1979). There is no actual livestock requirement or cautionary value assigned to electrical conductivity.
- Total Dissolved Solids: the measure of combined content of all inorganic and organic substances in the liquid. Total dissolved solids are either estimated from electrical conductivity measurements or measured in a laboratory by addition of measurements of the most prevalent ubiquitous substances. Total dissolved solid levels of 3,000 to 5,000 milligrams per litre (mg/L) are cautionary and levels greater than 5,000 mg/L are not recommended for livestock.
- Sulfates: sulfates as measured by a laboratory (or estimated from electrical conductivity and total dissolved solids) have two main impacts on ruminant health:
- Increased dietary sulphur to toxic levels, resulting in thiamine deficiency and Polioencephalopathy, and;
- Increased binding of and decreased absorption of trace minerals, resulting in a trace mineral deficiency. Sulfate concentrations of 1,000 to 2,000 mg/L are considered cautionary, greater than 2,000 mg/L not recommended and death can occur at 7,000 mg/L sulfates.
The Regional Offices for the Saskatchewan Ministry of Agriculture received and forwarded livestock water samples to the Saskatchewan Disease Control Laboratory with the Saskatchewan Ministry of Health. The Regional Offices in Swift Current and Moose Jaw were hardest impacted by dry conditions and were responsible for 394 submissions, 66 per cent of which were dugout water sources. Other sources included: wells, water lines, sloughs, creeks, coulees and dams.
The results of the water tests for dugouts in south-west and south-central Saskatchewan showed interesting results:
- Total dissolved solids: more than half the locations tested had potential issues, with 16 per cent percent of dugouts reporting cautionary levels between 3,000 and 5,000 mg/L and 37 per cent with unacceptable levels greater than 5,000 mg/L.
- Sulfates: while 40 per cent of dugouts contained an acceptable level of sulfate of less than 1,000mg/L, 11.5 per cent had cautionary sulfate levels between 1,000 and 2,000 mg/L, and 48 per cent of dugouts contained sulfate levels greater than 2,000 mg/L and were unacceptable for livestock use. This level of sulfates would have put animals at risk of rapid trace mineral deficiency or sulphur toxicity leading to blindness, Polioencaphalopathy or death. Out of all samples tested, roughly 10 per cent contained 7,000 mg/L or greater, which can prove fatal.
For livestock producers, total dissolved solids and sulfates can generally be calculated from electrical conductivity, which is why desktop and handheld meters are being utilized. In general practice, total dissolved solids were recognized as 64 to 71 per cent of the electrical conductivity measurement. However, for the dugout water samples taken in 2017, the total dissolved solids averaged 89 per cent of the electrical conductivity.
Individuals who sampled livestock water should heed caution when using 64 to 89 per cent of conductivity to estimate total dissolved solids, as each water sample is unique. Based on 2017 dugout data, there was a wide range of percentages measured that could have significant impacts on dugout water quality. There seemed to be a more accurate trend for predicting the sulfate concentration from the electrical conductivity value to range between 49 and 51 per cent of the conductivity. However, for water samples with electrical conductivity measurements of 2,000 µS/cm or less, there was no accurate prediction of sulfate as a percentage, whereby for samples testing greater than 2,000 µS/cm, sulfate levels were more closely estimated within the 49-51 per cent of conductivity range.
When desktop or handheld water metering were utilized, some meters were more accurate than others (recognizing that the gold standard in deriving a value is by analysis from an accredited laboratory). Water measurement devices that were more industrial in quality measured more accurately to laboratory based results. Given the wide variety of handheld meters available for public use, accuracy of each meter should be evaluated by comparing meter results against verified data from an accredited laboratory.
The primary lesson learned from sampling livestock water sources in 2017 is that each water source has to be considered unique and does not conform to an average value. Each water source needs to be tested individually as quality cannot be predicted from an average.
Livestock consumption of water and observations of behavior with respect to water sources are extremely valuable flags; often, livestock refused water that had high and elevated electrical conductivity, total dissolved solids, sulfates and even sodium. It is imperative to manage water sources as part of a husbandry program. Testing livestock water sources can prevent problems or assist in troubleshooting production/health issues. For 2018, producers are encouraged to evaluate and test livestock water sources to ensure quality is known and understood.
For more information on water quality or analysis for livestock, contact the Agriculture Knowledge Centre at 1-866-457-2377 or your local Saskatchewan Agriculture Livestock Specialist.