RENO, Nev. – After decades of losing ground to cheatgrass-fueled wildfires and spending millions of dollars on restoration efforts with mixed success, researchers are exploring a new rangeland management tool: cattle dung.
Cattle already play an important role in rangeland restoration through targeted fall grazing, which helps suppress cheatgrass, an invasive annual grass that has transformed millions of acres across the West. Cheatgrass grows quickly, dries out early in the season, and leaves behind highly flammable fuel that helps drive larger and more frequent wildfires. The grass also outcompetes native plants for limited moisture, making restoration increasingly difficult across much of the Great Basin.
Now, researchers at the University of Nevada, Reno are investigating whether the cattle that help suppress the cheatgrass can also help disperse seeds of beneficial perennial grasses through their manure, potentially supporting large-scale reseeding efforts across degraded rangelands.
In a newly published study, researchers found that specialized seed coatings helped native grass seeds survive conditions that mimic passage through a cow’s digestive system, increasing the likelihood that livestock could be used to deposit viable seeds across the landscape through their manure.
The findings build on earlier research by the team showing that cheatgrass seeds do not survive long enough in a cow’s rumen to remain viable. The rumen is the largest compartment of the cow’s stomach and serves as a fermentation chamber for digesting fibrous plant material. After spending approximately 32 to 36 hours in the digestive system, the seeds are effectively destroyed, meaning cattle can help reduce cheatgrass by eating it without spreading it to new areas through their manure.
“We’ve already shown that cattle can help us manage cheatgrass,” said the project’s principal investigator Tamzen Stringham, professor and rangeland ecology specialist with the University’s College of Agriculture, Biotechnology & Natural Resources. “The next question is whether we can use those same animals to help seed desirable plants across the landscape and support restoration at scales that would be difficult or prohibitively expensive using conventional methods.”
Coated versus uncoated seeds: Not every seed needs protection
The study, funded by Nevada’s Bureau of Land Management and the Public Lands Council, evaluated four grass species commonly used in Western rangeland restoration: Indian ricegrass, bluebunch wheatgrass, bottlebrush squirreltail and crested wheatgrass. Researchers tested whether specialized polymer coatings could protect seeds from the harsh microbial and digestive environment of a cow’s rumen.
“Originally, we thought we would need to coat every seed,” said Will Richardson, a postdoctoral researcher in the Department of Agriculture, Veterinary & Rangeland Science. “What we found was much more nuanced. Some species need that extra protection because the rumen environment quickly damages the seed, while others already have natural defenses.”
Results varied considerably among species. Coated crested wheatgrass showed some of the strongest performance, retaining viability during extended rumen exposure and successfully emerging from manure under greenhouse conditions. Bluebunch wheatgrass also benefited from the dual-layer coating, which helped maintain seed viability during prolonged digestion.
One of the biggest surprises was Indian ricegrass, a native Great Basin species with a naturally hard seed coat. Researchers found Indian ricegrass survived passage through the digestive system without additional protection and, in some cases, germinated more readily after 24 to 36 hours in the rumen. The digestive process appeared to naturally scarify, or weaken, the seed coat, helping break dormancy and prepare the seed for germination.
Researchers also tested whether seeds could germinate after being deposited in cattle manure. Under greenhouse conditions, coated crested wheatgrass successfully emerged from fecal material, demonstrating that some seeds can survive digestion and remain capable of establishing after dispersal.
“The results showed that different species respond very differently to digestion and coating technologies,” Richardson said. “For fecal seeding to be successful, we’ll likely need species-specific strategies rather than a one-size-fits-all approach.”
Forming a regional research network
The interdisciplinary project brought together researchers specializing in rangeland restoration, animal nutrition, seed technology and microbial ecology. The core research team included Stringham, who also conducts research as part of the University’s Experiment Station, Richardson and master’s graduate Graham Holton, along with collaborators from Texas A&M University and Brigham Young University.
Next step: Testing fecal seeding on working ranches
This fall, the project will enter its next phase at Horseshoe Ranch in northern Nevada. Researchers will mix coated seeds into protein supplements commonly provided to cattle and monitor small grazing paddocks to determine whether seeds that survive digestion can take the final step from germination to establishment in the field. The trials will track where cattle deposit seeds, how many seedlings emerge and whether the approach can be scaled across larger landscapes.
“At this point, we’re moving from asking whether seeds can survive the cow to asking whether they can survive the landscape,” Richardson said. “If we can successfully establish desirable perennial grasses using cattle that are already on the range, it could provide land managers with a practical restoration tool that works at the scale of the problem.”