As I am writing this article, it has been a very dry spring in many parts of Western Canada.
Our snow seemed to melt early and much of it seemed to evaporate and the sloughs and dugouts did not seem to fill with much runoff. Hopefully, by the time this article is published, we will have had some good rain and the grass will be growing.
However, as we begin to think about turning our herds out to pasture, it seems like a good time to remind beef producers to think about getting your cow’s water sources tested for quality, especially if they rely on dugouts, sloughs or shallow lakes and in some cases deep wells.
In many parts of Western Canada, these types of water sources can begin to concentrate mineral levels, especially when we haven’t had normal amounts of precipitation and runoff. The most common problem that is often identified in these situations is associated with high sulfate levels.
There are many good guidelines for livestock water quality available but a general rule of thumb is that water with less than 1,000 parts per million (p.p.m.) of sulfate will be acceptable for beef cattle to consume. Once sulfate levels are between 1,000 p.p.m. and 2,000 p.p.m., effects on animal growth and performance can sometimes be seen.
Sulfate interacts and binds with copper, making it unavailable to the animal. This can result in a copper deficiency, which is sometimes referred to as a “secondary copper deficiency” caused by the antagonism of the sulfate mineral in the water or the diet.
Copper deficiency can create low growth rates, anemia and hair colour changes but the greatest production limiting effect is reduced fertility resulting in low pregnancy rates.
Many areas of Western Canada already have low copper levels in forages, which results in low copper levels in cattle that consume these forages. Some preliminary results from our Western Canadian Cow-Calf Surveillance Study have shown that the majority of cows sampled in our study had below adequate levels of copper. Many herds had less than half of the sampled cows with adequate copper levels.
If we compound a situation that already has marginal copper levels by adding water with sulfates greater than 1,000 p.p.m., we can easily create a secondary copper deficiency that will cause significant problems affecting cattle fertility and pregnancy rates.
As sulfate levels in water climb higher, we can see other signs of toxicity. If water sulfate levels are greater than 2,000 p.p.m., we may begin to see signs of nervous disease in the cattle.
Polioencephalomalacia (or PEM) is the scientific term for a nervous disease of cattle that is characterized by blindness, difficulty walking and seizures. Eventually the animals will become recumbent and often go on to die. Some animals with less severe forms of PEM may recover but still have some minor neurological symptoms. If the animal consumes water or feed with exceptionally high levels of sulfate, hydrogen sulfide gas is created in the rumen and is absorbed into the blood stream.
Hydrogen sulfide has a toxic effect primarily on the brain and the result is an animal showing the many nervous system symptoms of PEM. If water sulfate reaches 3,000 or 4,000 p.p.m., the development of PEM becomes even more likely.
It is especially important to emphasize that the mineral levels in a water source are very dynamic. As it gets warmer, further evaporation of dugouts or other standing water sources can occur. The water evaporates but the minerals remain, which results in a greater concentration of minerals. This can change the levels of sulfates quite quickly and change water from an acceptable quality to a toxic level in a matter of days.
In addition, as the weather gets hotter, cattle tend to increase their water consumption. This can further compound the problem because now the cattle are drinking more and consuming higher levels of minerals as well.
Water that is high in sulfates is not very palatable to cattle and if given a choice they will choose another water source. However, if there is no other water source, the cattle will eventually consume the high sulfate water and can show signs of toxicity.
Even then, cattle may drink reluctantly and can be observed attempting to drink but allowing water to dribble out of their mouths. The palatability of high sulfate water is very poor, but thirst is an even stronger motivator and cattle will eventually consume this water.
You can send water samples to provincial testing laboratories in most provinces and the tests for dissolved minerals usually include sulfates, conductivity, and total dissolved solids.
Your local veterinarian or provincial livestock extension specialists will be able to help you interpret the results to determine if the water source is of acceptable quality for your cattle.
If you need a quicker answer about your cattle’s water source, there are a number of hand-held conductivity meters that can test the electrical conductivity of the water. These hand-held meters need to be calibrated correctly and verified against laboratory results, but they provide a rapid assessment of water quality by measuring electrical conductivity, which is associated closely with levels of total dissolved solids and sulfate levels.
Work by the Saskatchewan Ministry of Agriculture showed that an electrical conductivity of 3500 uS/cm or greater is accurate in predicting that water sulfate levels are higher than the dangerous 2,000 p.p.m. level. If you live in a region that has been affected by water quality, your local livestock extension specialist or local veterinarian may even have a hand-held electrical conductivity meter that could provide you a rapid assessment of your cattle’s water quality.
I am hoping for some significant precipitation so that our pastures produce lots of grass, our forages and grain crops grow and our cattle’s water quality is good.
However, if you do rely on standing water sources for your herd, make sure you test the water quality at regular intervals throughout the summer. Water quality is not static and it can change quickly and the consequences can be dramatic.
John Campbell is a professor in the department of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.