Sulfates: how much is too much?

Sask. researchers launch a study that they hope will determine the level of sulfates in water that cattle can tolerate

Water high in sulfates can kill cattle, and a new study based at the University of Saskatchewan seeks to learn more about livestock tolerance.

When more than 200 cattle died in southwestern Saskatchewan in July 2017 after drinking water with lethal amounts of sulfates and dissolved solids, it emphasized the need for more information.

Leah Clark, livestock and feed extension specialist with Saskatchewan Agriculture, was among those who answered that call.

“We don’t like to focus on that,” Clark said about that massive cattle loss near Shamrock, Sask., “but that really gave us the opportunity to have an open ear about this project.

“What prompted the study was just the amount of issues that we see with sulfates in water affecting producers, both sub-clinically and the effects it has on mineral status of animals, but also clinically in terms of … producing polio in animals.”

Clark and her livestock extension colleague Colby Elford are leads on the research project being managed by Dr. Greg Penner, an associate professor at the U of S and chair in ruminant nutritional physiology.

Using new facilities at the Livestock and Forage Centre of Excellence at Clavet, Penner is studying 32 heifers in groups that are given different amounts of sulfates in their water, ranging from zero to 3,000 parts per million. The animals’ water intake, feed intake and body weight gain are being measured over an 84-day period.

“The challenge we have is we don’t know all that well what levels we require when we’re dealing with high-sulfate water, or if we can just feed more inorganic mineral and override that negative reaction,” said Penner.

Clark said Saskatchewan and Alberta cattle producers are well aware that groundwater sources can have high sulfate amounts, but data is lacking on just how much cattle can tolerate without adverse effects.

“The levels that we use for acceptable sulfates are based more on anecdotal evidence and previous research done in feedlots and dairy,” she said.

Since those animals are generally pushed harder than pasture cattle in terms of growth and production, more specific research is needed.

The issue has become more prominent in recent years because of dry conditions in much of Saskatchewan and Alberta. As surface water in dugouts evaporates, salts are left behind and become more highly concentrated in the remaining water.

“Most of the sulfate is coming from groundwater reserves, so it’s an artifact of the underlying mineral composition of the below-ground material,” said Penner.

Producers may have few options when it comes to supplying alternative water sources, said Clark, and they may not realize there’s a problem until it’s too late. Although cattle can develop a tolerance to some level of sulfates, and supplied minerals can reduce the effect, data is needed on what those levels are and what can be done to assist.

“What we’re really worried about as livestock specialists is what are these lower levels that are causing production problems costing our producers and how can we mitigate those symptoms,” Clark said.

“What we’re really trying to assess is the effects of different levels of sulfates on production.”

The salts can tie up other trace minerals within the animal so they can’t be adequately used. Clark cited copper, zinc and manganese as examples. Each is important to fertility, milk production, reproduction and energy.

Sulfates also affect cattle production of thiamine, a B vitamin typically produced in the rumen. Lack of thiamine causes central nervous system lesions, leading to symptoms including staggering, blindness and in extreme cases death.

Clark and her colleagues are hoping the current study paves the way for future research on management practices and mineral supplement options.

“I think water is just kind of that forgotten nutrient and so, as sad as that issue was at Shamrock, it’s now on our radar and we’ve been able to capitalize on that to get the word out about the impacts of sulfates and how to work with them,” said Clark.

The project is funded through the Canadian Agricultural Partnership, a federal-provincial program, at a cost of $82,900. Penner said results are expected in June.

Clark added that the Saskatchewan Cattlemen’s Association’s contributions to the livestock and forage centre were instrumental in getting proper facilities for the research.

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