Safe levels of sulphate in cattle drinking water may be higher than current guidelines, scientists found
Cattle can likely tolerate higher levels of sulphate than current recommendations allow, scientists from the University of Saskatchewan (USask) and extension specialists from the Saskatchewan Ministry of Agriculture have found.
This discovery is significant because water in Saskatchewan can have high sulphate concentrations, which can have negative effects on cattle. So, understanding the tipping point between acceptable and unacceptable levels is vital.
Scientists conducted the work with 32 heifers at USask’s Livestock and Forage Centre on Excellence. The researchers began the study in Nov. 2018 and concluded in June 2019. The ministry’s Strategic Field Program supported the project.
In the study, researchers increased sulphate concentrations to 1,300 milligrams (mg), 2,600 mg and 4,300 mg per litre of drinking water for the cattle. The control was 300 mg per litre of water.
The provincial and national recommendations of sulphate in drinking water that is safe for cattle ranges from 1,000 to 2,500 mg per litre of water.
“In terms of our results, we saw very little effect on feed intake or water intake and no effect on growth. (These findings) suggest that we probably can get away with higher sulphate concentrations in the water,” said Greg Penner. He’s an associate professor in the department of animal and poultry science at USask and the centennial enhancement chair in ruminant nutritional physiology.
Penner completed the study with Leah Clark, the province’s livestock specialist, Colby Elford, a livestock and feed extension specialist, and two student researchers Jordan Johnson and Brittney Sutherland.
While this study showed some changes could be made to the recommendations, a cause for concern existed because of the associated change in the cattle’s copper levels.
“We saw a reduction in the copper concentration in their blood. Copper is one of those minerals that sulphate interacts with and copper is also linked to reproduction. So, cattle with a lower copper concentration are less likely to become and stay pregnant,” Penner told Farms.com.
As the amount of sulphate increased in the drinking water, copper decreased. However, this mineral remained at adequate levels in all the heifers and no deficiencies existed, said Penner.
The findings “give us a little bit of concern. These cattle were housed in top-notch conditions. They were in environmentally controlled barn. Their diet was formulated adequately and we know the cattle consumed adequate amounts of their diet. So, if you don't have all those conditions, the risk for a (copper) deficiency may be possible,” said Penner.
Since this was the first study they have completed on this sulphate concentrations, the researchers are reluctant to suggest a change to the guidelines. However, the government might be able to soften them, said Penner.
The scientists plan to continue studying sulphate in drinking water and they have received two contracts for additional research. One study will test conditions in an outdoor setting during the summer and the other project will look at helping cattle maintain their mineral status if they have access to water high in sulphate, said Penner.
“We're trying figure out how we can sustainably use water sources and land bases that would not be suitable for” other types of agriculture, said Penner. “This really is just a small piece in the sustainability picture in beef cattle production.”
Photo credit: Livestock and Forage Centre of Excellence, University of Saskatchewan