By Jamie Shanks, Communications Branch, Regina
It began in 2018 as an evaluation of long-standing recommended thresholds for sulphate concentrations in water sources for cattle—and now, in the wake of that project’s results, University of Saskatchewan researchers are going with the flow to find the answers to another question.
of sulphates in water sources than previously thought,
but there are long-term implications.
A surprise of sorts awaited Dr. Greg Penner, professor in the Department of Animal and Poultry Science and the Centennial Enhancement Chair in Ruminant Nutritional Physiology, who led the study conducted at the Livestock and Forage Centre of Excellence near Clavet. It turns out that cattle can tolerate short-term exposure to considerably higher levels of sulphates in water than previously thought, and in fact they can do quite well from a feed intake and growth perspective.
With water quality often top of mind for livestock producers in Saskatchewan, that seems like a good thing—but Penner advises pumping the brakes on this angle.
“I think we need to put some limitations around that,” he says, while also acknowledging the positive findings regarding risks for polioencephalomalacia, a neurological disease in ruminants. The study’s results suggested that past outbreaks of polio probably haven’t been driven solely by high sulphates in water supplies and cattle may actually have tremendous capacity to tolerate high-sulphate water without developing the disease.
“With the studies we’ve conducted, we’ve been able to isolate high levels of water sulfate from other factors that might increase risks for polio. Cattle that are grazing may actually have other risk factors, like high sulphur in some of the forages they’re consuming,” he says.
“It doesn’t change the fact of what we’ve observed in the past in the field … it just starts changing where we start looking for the risk factors for polio.”
However, and perhaps more importantly, it’s what the study revealed about trace minerals that caught researchers’ attention: when cattle are drinking high-sulfate water, trace mineral status is compromised and, in particular, their liver copper is depleted. The impacts of such a deficiency may not be immediately evident, but copper has important roles in biological processes ranging from antioxidant status to reproduction and other research has indicated that ensuring cattle have sufficient copper levels can be a common concern for producers in Saskatchewan.
The focus now, Penner says, is determining whether trace mineral feeding strategies can be adjusted to avoid declines in liver copper that occur in conjunction with long-term exposure to high sulphate concentrations in water sources—at least with concentrations lower than 5,000 parts per million, a level at which mineral feeding strategies no longer appear likely to be effective. So far, ongoing work shows that injectable trace minerals, used appropriately, may have promise as a potential option.
None of this would have come to light without Saskatchewan’s Strategic Field Program, which provides joint federal-provincial funding through the Sustainable Canadian Agricultural Partnership for this and similar research.
“Without the Strategic Field Program, we probably wouldn’t have pushed into this area as much as we have,” Penner notes, especially acknowledging the initial and continuing role of the Ministry of Agriculture.
“It was really driven by the livestock extension specialists who encouraged us to look at this.”