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Minimizing pathogen loading can increase stocking rates on western rangeland

by Wyoming Livestock Roundup

“Applying science to management is the key in reducing pathogen loading in water sources across the West,” said Ken Tate, University of California-Davis rangeland watershed specialist. 

Tate spoke about ways cattle producers can minimize pathogens introduced to water sources at the Wyoming Association of Conservation Districts Watershed Conference held in Casper Feb. 20-21.

Fecal distribution 

“We have to ask ourselves how cattle distribute their feces,” said Tate. 

Tate joked much of his research in college boiled down to “putting poop in bags” to collect data. Through his research, he found over 60 percent of cattle fecal loading occurs near attractants. 

“We figured out the cattle defecate closer to things like salt, feed and water,” he explained. “So, if we could position these attractants as far away from streams and rivers as possible, then we could prevent pathogens from traveling through the water sources.” 

“When we have incidents like the E. coli outbreak in lettuce in 2018, people want to blame cattle,” he noted. “We have to understand there are wildlife populations that factor into pathogen loading, as well. Not to say cattle don’t magnify this, but they are not the sole contributors.” 


“To understand the distribution, we also had to determine if and how the pathogens mobilized from the original cow pat,” Tate said. “To determine this, we stirred bacteria into a cow pat and dosed a runoff plot to simulate rain or irrigation.” 

“We found over 90 percent of microbes were stuck to the original pat or within one foot of it,” he explained. “Of the remaining percentage of microbes, between 70 and 99.9 percent were trapped within a single yard of the pat.”

He explained this is especially important to consider because infected runoff can wreak havoc on wetlands. Runoff into streams can affect water supply to people, as well as plants. 

Managing for pathogen 


“We want to manage cattle and pastures in such a way that we reduce pollution,” said Tate. 

“This really all goes back to soil health,” he commented. “When we can properly manage our soils, water and forages, we will be more profitable and better stewards of the land.” 

“We want moderate stocking rates,” he said. “There needs to be a balance with forage production and site resiliency to reduce impacts to soil and vegetation.”

He explained managers should also manage livestock distribution across the land to minimize pathogen loading and pollution. 

“When we distribute livestock more effectively through the land, we can in turn distribute waste in a more efficient way,” Tate said. “Distributing across the landscape will increase microbe decay and travel distance to upland attenuation.” 

“We also have to manage riparian areas,” he noted. “We want to distribute livestock onto resilient soils and uplands during wet periods to minimize damage on these sensitive areas.” 

He recommended a mix of rest and rotational grazing, cross fencing, riparian pastures, off-stream drinking water, targeted supplement feeding, herding and movement of cattle and vegetative buffers.

“We essentially want to get pathogens as far from the water as possible,” he noted. 

Source and sink pastures

“We also want our pastures to be sink pastures,” he explained. “These types of pastures not only ensure we are reducing pathogen loading and pollution but also maximize soil health and profits.” 

“What we don’t want to have is a source pasture,” he said. “That means the pasture is the source of pollutants.” 

“A source pasture will have high run-off rates, overstocking, discharge to streams, direct access to streams and cattle are able to graze immediately after irrigation,” he explained. “These are pretty much all practices we want to avoid because they’re bad for the environment and bad for the bottom line in the long-run.” 

“On the flip side, we have sink pastures, which is what we want to have,” he said. 

He described sink pastures as having moderate stocking rates, reduced runoff, a buffer to wetlands and limited access to streams. 

“When we have sink pastures, the soil health is better, and we can actually double our stocking rate over time because we took care of the land,” he noted. 

Callie Hanson is the assistant editor of the Wyoming Livestock Roundup. Send comments on this article to

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