Research increases cheatgrass grazing options for cattle

By Andrew Church
In a state plagued by rangeland wildfires, research conducted by the University of Nevada, Reno's College of Agriculture, Biotechnology and Natural Resources is working towards developing preventative fire strategies. The solution?

Livestock grazing. Bromus tectorum, or cheatgrass, is an invasive plant species to Nevada, having originated in Eurasia. Its dispersion across Nevada is due in part to its off-season growth pattern and rapid development. According to University of Nevada Cooperative Extension, cheatgrass covers nearly 17 million acres in the Great Basin.

Cheatgrass seeds germinate in the fall and early winter, which provides it extra time to begin growing during early spring. The lifecycle of cheatgrass ends in early summer, when the plant begins to dry out and disperse its seeds. The unique lifecycle of cheatgrass is what also makes it a fire hazard. Dry and dead cheatgrass found in the summer months provides an abundant source of fuel for rangeland fires.

According to Barry Perryman, associate professor in the Department of Animal Biotechnology, the presence of cheatgrass increases the occurrence of rangeland fires from every 40 to 100 years to two to five years.

"As an annual grass, cheatgrass tends to reach peak production before native perennials," Perryman said. "As a result, cheatgrass tends to dry out by early summer, which creates a fuel source and increases the frequency of fires."

Repeated fire exposure also takes its toll on native plant species, destroying native flora and replacing it with cheatgrass. In turn, the removal of these native plants disrupts the ecology of affected areas. Animal species such as the sage grouse and the pygmy rabbit depend on sagebrush habitat, and are impacted negatively by its loss.

"As fires become more and more frequent, cheatgrass tends to grow and spread," Perryman said. "Whereas an annual plant such as cheatgrass will replace itself, repeated fires inhibit the growth of perennial plants."

The use of cattle to reduce the spread of cheatgrass is not a new strategy. However, it has been traditionally thought that livestock will only consume cheatgrass during the spring months when the plant is green and developing. Seeding plants seem to be avoided by grazing animals. Additionally, many thought that dry cheatgrass contained less nutritional value. Operating under these assumptions, livestock grazing strategies have been targeted towards reducing cheatgrass during the spring months.

However, Perryman argues that spring grazing poses several logistical challenges. As cheatgrass growth varies per year depending on weather and precipitation, it is often difficult to develop a detailed plan for spring grazing. Secondly, it is also problematic to gauge how many animals are needed to reduce cheatgrass coverage to a desired amount, or how much time it would take to do so. Many cattle producers that operate on public lands are allotted a certain amount of time to graze, which impacts the effectiveness of these strategies. In response, Perryman has worked to investigate the preconceptions about cheatgrass grazing, and has offered different conclusions.

One observation he has made concerns the nutritional content of dry cheatgrass. "Cheatgrass is quite nutritious in the spring, but when it sets seed it becomes unpalatable for livestock, and they stop consuming," Perryman said. "We have discovered that dry cheatgrass still contains good protein and energy content. Just because animals quit eating it doesn't necessarily mean it's not nutritious."

Perryman also argues that once the grass has dropped its seed, animals will resume eating it. This creates grazing options for cattle producers in late summer and early fall. "These new strategies can solve many of the logistical problems of spring grazing," Perryman said. "Unlike in the spring, we can observe and measure cheatgrass growth more effectively in June and July.

We can also analyze the nutrition content of the dry cheatgrass. This allows producers to develop better, more consistent strategies for late grazing." Ultimately, the use of these strategies not only provides livestock producers with additional grazing options, but also works to mitigate the damaging effects of rangeland fires.