By Mitch Stephenson
Targeted livestock grazing is the application of grazing animals at a defined time, intensity, and duration for vegetation or landscape management objectives. When planned right, targeted grazing management can accomplish those objectives without negatively affecting livestock production. Understanding plant growth and livestock grazing preference is important to the success of targeted grazing.
Cheatgrass impact
Cheatgrass (Bromus tectorum) is an introduced annual grass that has invaded many acres of native rangelands in western Nebraska and eastern Wyoming. Cheatgrass typically starts growing in the fall and continues growth in the early spring before many of the native perennial grasses. During the early spring when temperatures and precipitation are ideal for growth, cheatgrass can outcompete perennial grasses for water and nutrient resources, which can displace native species and reduce ecosystem stability and resilience.
Once cheatgrass matures and goes to seed, grazing animals change their focus to the surrounding perennial grasses, so the most effective time to graze cheatgrass to reduce the spread is when the grass is at least 3.5 inches tall, but not seeded out yet, usually in May and June, depending on temperature and weather conditions. Photo courtesy of Mitch Stephenson, Nebraska range management Extension specialist.
Targeted grazing research
Research conducted from 2017 to 2020 by the USDA-ARS and the UNL Panhandle Research, Extension, and Education Center explored how cattle can be used for targeted grazing on cheatgrass. The goal of this project was to track the intake of cheatgrass by cattle early in the growing season to determine when they were most likely to consume cheatgrass and how this might vary in different years. Fecal DNA analysis was used to reconstruct diets of cattle based on the DNA of plant species in fecal material (See attached handout). Additionally, GPS collars were used to evaluate when cattle used areas with higher amounts of cheatgrass or native grass.
Research findings & recommendations
Cattle consumed the most cheatgrass in their diets when the plants were at least 3.5 inches tall and this preference was observed until the seeds matured. This period lasted on average 38 days in May and June, but preference was variable depending on weather conditions. After seeds matured, cattle selection for cheatgrass plants was reduced and greater grazing pressure was observed on native perennial grasses in the pastures. GPS tracking also indicated that as cheatgrass matured cattle utilized native grass areas without cheatgrass for a greater proportion of the time than areas with cheatgrass.
During the study, early-season targeted grazing on cheatgrass reduced seed production by 38% to 77% compared to ungrazed areas depending on the year and location. Management that reduces the amount of cheatgrass seed production provides opportunities to reduce the competition of cheatgrass while still providing a high nutritive value forage for livestock in the early spring.
While cheatgrass is challenging to manage, incorporating targeted grazing into grazing plans offers opportunities for livestock producers to benefit from the quality of cheatgrass when it is most palatable while reducing cheatgrass seed production.
Source : unl.edu