Connee Quinn’s terse note to herself from the summer 2002 is as searing as the drought that withered that year’s shortgrass prairie: “Hot and dry,” she wrote. “Lost 12 head.”

It wasn’t the first time she and her husband, Reuben, had learned how devastating the Great Plains environment can be on livestock. It was worse in 1998, when 15 head died of mysterious causes, while others got sick.

For the Quinns, who ranch in southwestern South Dakota and live near Chadron, NE, it was like a multiple-choice test question with no good answers. “The symptoms of the cows that were still alive indicated some type of central nervous disorder,” Connee says. At first they suspected poisonous plants. Their veterinarian’s early suggestion was selenium poisoning, a good guess since selenium poisoning is an ongoing problem in the area.

But the final answer to a question with life and death consequences was sulfates in the water.

With the summer 2008 shaping up to be hot and dry for parts of the nation’s rangeland, sulfate loads in livestock water may again be a concern. Couple that with the recent use of distillers grains and other corn byproducts as a feed supplement, which can also be high in sulfur, and the question becomes even more critical – how much sulfate in the water is too much for cattle?

Research results vary slightly, but Ted McCollum, Texas AgriLife Extension beef specialist in Amarillo, says generally, sulfate levels below 600 parts per million (ppm) is considered good, safe drinking water. Concentrations up to 1,000 ppm begin to move you into marginal water quality. “As you move up from that, you can potentially start having various types of problems,” McCollum says.

Those problems are substantial:

  • Several South Dakota State University (SDSU) studies show water sulfate levels of about 3,000 ppm or greater reduced performance and health of growing steers in drylot during summer months.

  • Steers grazing native rangeland had lower gains when supplied water with sulfate levels of about 4,000 ppm or greater.

  • In studies involving cow-calf pairs, water averaging 2,600 ppm sulfates resulted in little impact on calf growth or milk production, but did result in small reductions in cow bodyweight and body condition scores.

  • In another SDSU study on cow-calf pairs, animals on high-sulfate water (averaging 3,045 ppm sulfates) had lower 12-hour milk production in August (7 lbs. vs. 9 lbs. for low-sulfate water). Calf average daily gain tended to be higher for low-sulfate treatment groups (2.56 lbs./day compared with 2.45 lbs./day). A greater percentage of cows on low-sulfate water became pregnant during the first 25 days of the breeding season (81% compared with 64%) and final pregnancy rates were higher for the low-sulfate group (92% to 83%).

  • A three-year SDSU study found no differences in the incidence of polioencephalomalacia (PEM) between steers on high-sulfate water receiving supplemental thiamin, and those on high-sulfate water receiving no thiamin supplement. Thiamin injections are often used to treat sulfate-induced PEM in beef cattle, but the SDSU study was looking at what role supplemental thiamin might have on PEM.
Bottom line. “Usually around 3,000 to 4,000 ppm of sulfates in your water, expect some bad consequences,” McCollum says. Those consequences may include unexplained reproductive problems and health problems, reduced gain and, at the extreme, unexplained death loss.

Minnesota research found sulfate levels of 1,000-2,000 ppm may result in diarrhea and limit copper availability. Levels from 2,000-3,000 ppm may cause a substantial reduction in copper availability. That’s important in herd health, McCollum says, as the effects of mineral deficiency come to the fore.

One of those effects is a severely compromised immune system, according to John Peirce, veterinarian with AzTx Cattle Co. in Hereford, TX, a cattle feeding and ranching operation. In Peirce’s experience, calves originating from ranches with high sulfates in the drinking water simply don’t respond to a vaccination program.

And in research from Saskatchewan, sulfate concentration at 7,000 ppm results in death due to sulfur toxicity or PEM. The Quinns can testify to that. At the time they were losing cattle, their waterholes tested from 5,500-13,500 ppm sulfates.

Also at the time they were losing cattle, it was summer and a drought – two factors that can substantially increase the potential for sulfur-toxicity problems. Cattle may drink more than 2 gals. of water/100 lbs. of body weight when temperatures exceed 80° F, more than twice the intake of a 1,000-lb. animal at a temperature of 40° F.

Then factor in drought. As tanks draw down, the salts will concentrate. “Under normal rainfall, ranchers may not have a problem (with sulfate concentration in waterholes),” McCollum says. “But in times where those ponds are drawing down and concentrating, they may see some problems.”

The same thing can happen with wells. And if those wells draw from a stratum with a high mineral content, that’s going to show up in the water.

Just like surface tanks, minerals can concentrate in the well water as the water table draws down. Conversely, if the water column moves into a stratum containing less sulfate-bearing minerals, water quality may actually increase.

The point is, McCollum says, you don’t know unless you test your water. And while it’s not necessary to retest every year, it might be advantageous to test your water every couple of years, especially if you’re battling drought.

That’s even more important if you’re looking to add distillers grains or corn gluten feed to your supplement menu. If your water is running 1,000-2,000 ppm sulfates, you can usually get by with minimal consequences, McCollum says, as long as no additional sulfur intake occurs.

“Then you start using corn gluten feed or distillers grains as a substantial portion of the diet, which increases the overall sulfur intake from the feed,” McCollum says. “And you’ve suddenly gone from a situation where you used to not have a problem and now you do.”

Feed research. Research is underway at SDSU to find a feed additive that can help reduce sulfur toxicity, says Ken Olson, SDSU Extension beef specialist in Rapid City. When an animal ingests a sulfur compound, free-range hydrogen ions roaming around the rumen cause a conversion to hydrogen sulfide, which is the toxic agent.

If researchers can find an agent that binds those hydrogen ions, they hypothesize that they can reduce the production of hydrogen sulfide and reduce the effects of sulfur toxicity.

Work last summer looked at Zeolite, a mineral compound fed to dairy cattle and swine that binds ammonia in the gut and reduces the amount of available ammonia in the manure. However, when fed at levels recommended for an ammonia response, no response was found in the level of sulfur toxicity.

“So our silver bullet is still waiting out there for us to discover it,” Olson says. They’ve done some lab work over the winter to get a better idea of dose rates and will run a second set of trials this summer.

If they do discover an agent that reduces hydrogen sulfide, Olson says it may also allow greater use of distillers grains and other corn milling products in both feedyard and pasture operations.

Management considerations. If you’ve got pastures with high sulfate concentrations in the water, about all you can do is figure out how to live with it. That’s what the Quinns do. “The way we handle it is to go into those areas with poor water when the demand for water is less,” Connee says. “That would mean winter, early spring. We stay out of those areas in the hot summer.”

Since mature animals are slightly less susceptible to sulfates than young, growing animals, McCollum says another option is to use pastures with poor water for cows and run your steers or replacement heifers in pastures with lower sulfate water.

And if no other options are available, Olson says you may have to haul or pipe good water to your pastures. Then you can either mix it with the high-sulfate water or shut off the wells and provide alternative drinking sources with the imported water.

While the Quinn’s experience was difficult, they say it’s raised awareness that water quality is a bigger issue than some producers had realized. If you’ve got high-sulfate water, your options are limited and there are no good choices. But the dose makes the poison and while you may have to suffer through some summer sulfate problems, help may be on the horizon.