**5. Conclusions**

McCartney and Bittman [20] and others [29–31], suggest that timing and grazing capacity for optimal forage utilization and weed control, with minimal harm to desired species, requires thoughtful management to improve or maintain rangeland health. Our results show that mob grazing (225,000 or 50,000 kg of cattle ha−1 day−1) could reduce biomass of *Artemisia absinthium* a less palatable species in a pasture. In mob-grazed treatments, *Artemisia absinthium* plants appeared to be consumed if plants were small and, most likely, still had herbaceous, rather than woody, stems. Mob grazing offers the additional benefit of trampling which reduced *Artemisia absinthium* height, although not necessarily the volume, especially of larger plants. Effectiveness of mob grazing is dependent on plants species present, stocking density, and timing [14, 16, 20]. Grazing weeds should be avoided after seed set to minimize seed dispersal, as some weed seeds remain viable or increase in germination after ingestion and passing through the digestive tract of livestock [32, 33]. While we did not find literature that specifically addresses changes in *Artemisia absinthium* seed viability after animal ingestion, *Artemisia absinthium* seeds mature in late August or September [34], after the grazing events of our study, and was not investigated. If grazing an infested pasture must be delayed until a species is past its most palatable stage, or if a weed has inherently low palatability, higher stocking

Mob grazing with cattle has been proposed as a grazing system to increase forage use efficiency and help in landscape restoration [14] and is likened to grazing patterns of the native plains bison. Kohl et al. [35] reported that bison and cattle differ in grazing, standing, bedding, and moving behaviors, with bison moving from 50 to 99% faster and foraging up to double the land area than cattle during the same duration. This is the precedent for the frequent moves when mob grazing cattle. In addition, cattle, when not pressured, tend to select high plant biomass, whereas bison tend to select intermediate plant biomass [35]. Regardless of the inherent differences between these two species, when managed correctly, mob grazing with cattle can diversify grazing time, with frequent moves, and long rest periods [30]. However, if managed incorrectly, high intensity grazing systems could increase weed infestations [31]. For example, in 3 years, under medium grazing intensity (grazed five times year−1 with 6 cm of vegetation remaining after each grazing event) weeds increased by about 4 plants m−2, whereas under high intensity (grazed seven times year−1 until surface exposure), weed densities increased by 51 plants m−2 [36]. Hart et al. [37] reported that stocking rates that alter grazing frequency and defoliation intensity, rather than grazing system, have greater potential to impact species composition. Plant diversity and complex mixtures of forage species are integral to healthy ecosystems and consistent yields [38, 39]. However, mob grazing, if repeatedly used in the same area and at the same seasonal timing, could decrease plant species diversity and richness, change functional

plant traits (e.g., tall vs. short), but improve productivity of the remaining plants [40].

The animal of choice for grazing also can influence grazing results. Goats (*Capra aegagrus hircus*) and sheep (*Ovis aries*) [7, 41] are often suggested to control brush and other undesirable vegetation, as they are more efficient at foraging and have faster growth rate than cattle. However, there are to numerous disadvantages to using goats and sheep which include: poor return on investment due to low per capita consumption of their meat products in the US and low wool prices; limited genetic improvement in milk or meat production; high predation rates compared with cattle; difficulty in fencing confinement; and susceptibility to internal

rates, as seen in this study and other studies [7] improved suppression.

64 Forage Groups

Healthy rangelands grow more grass which aids in *Artemisia absinthium* control by preventing infestations and providing competition to newly establishing plants. Grass density can be optimized by managing livestock to minimize overgrazing through rotational grazing or avoiding heavy, early season grazing [22]. Based on *Artemisia absinthium* size increase in the 2014 recovery area after the early spring rotational grazing/summer rest, it appears that rotational grazing later in the growing season (as in 2013) achieved better suppression of *Artemisia absinthium* patches, although cattle did not necessarily consume *Artemisia absinthium*.

Once present, our study showed that grazing provided temporary reductions to *Artemisia absinthium* patches, with greater reductions in the mob-grazed and rotational/spray treatments than the rotational grazed treatment. Shoots of smaller plants and those in smaller patches appeared to be consumed in both mob grazing and rotational grazing when 2,4-D ester was applied. However, even the most decimated plants had shoots the following season. Once pastures are infested, long-term management plans are needed to keep *Artemisia absinthium* in check.

We found that mob grazing with cattle for 12 or 24 h in pastures where *Artemisia absinthium* was present did indeed improve *Artemisia absinthium* control of smaller plants (as measured in plant volume) with concomitant high forage utilization. Rotational grazing at lower stocking rates for 20 days (late-May through mid-June), when combined with 2,4-D application, also suppressed *Artemisia absinthium* for that growing season. Early (mid-April) rotational grazing with a summer rest resulted in much larger *Artemisia absinthium* plants and patches in the fall. We could not verify the statements that mob grazing would result in (1) an increase of two or more cm of soil per year, nor (2) a species composition change due to the intense grazing, which are two positive benefits of mob grazing often discussed in trade journal articles [15, 19, 52]. In addition, we did not assess the impact of mob grazing on animal performance, although in a single one-time grazing situation, a change in this parameter would not be expected. Long term management plans are needed for *Artemisia absinthium*, as all *Artemisia absinthium* patches observed after the first grazing season produced shoots the year following grazing, regardless of the amount of grazing or trampling damage that was sustained.

[4] Plant Protection Act. 7 U.S.C. 7701 et seq. 114 stat. 438 [Internet]. 2000. Available from: http://www.aphis.usda.gov/plant\_health/plant\_pest\_info/weeds/downloads/PPAText.

Mob vs. Rotational Grazing: Impact on Forage Use and *Artemisia absinthium*

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67

[5] Ohlenbusch PD, Towne G. Rangeland Weed Management. KState Bulletin, MF-1020 [Internet]. 1991. Available from: www.bookstore.ksre.ksu.edu/pubs/mf1020.pdf [Accessed:

[6] Sellers BA, Ferrell JA. Weed Management in Pastures and Rangeland—2017. University of Florida IFAS Extension [Internet]. 2017. Available from: SS-AGR-08.edis.ifas.ufl.edu/

[7] Frost RA, Launchbaugh KL. Prescription grazing for rangeland weed management: A

[8] Holechek JL. Comparative contribution of grasses, forbs, and shrubs to the nutrition of

[9] Bailey DW, Brown JR.Rotational grazing systems and livestock grazing behavior in shrubdominated semi-arid and arid rangelands. Rangeland Ecology Management. 2011;**64**:1-9

[10] Senft RL, Rittenhouse LR, Woodmansee DRG. Factors influencing patterns of cattle grazing behavior on shortgrass steppe. Journal of Range Management. 1985;**38**:82-87 [11] Fishel F. Plants Poisonous to Livestock. Columbia, MO: University of Missouri Extension;

[12] Crider FJ. Root-growth stoppage resulting from defoliation of grass. U.S. Dept. Agr.

[14] Savory A, Butterfield J. A commonsense revolution to restore our environment. In: Holistic Management. 3rd ed. Washington, DC: Island Press; 2016. 552pp. ISBN:

[15] Gordon K. Mob Grazing 101. Herford World [Internet]. 2011. Available at: www.Herford. org; hereford.org/static/files/0111\_MobGrazing.pdf [Accessed: December 15, 2017] [16] Barnes MK, Norton BE, Maeno M, Malechek JC. Paddock size and stocking density affect spatial heterogeneity of grazing. Rangeland Ecology & Management. 2008;**61**:380-388 [17] Pleasants AB, Shorten PR, Wake GC. The distribution of urine deposited on a pasture

[18] Frank DA, McNaughton SJ. Evidence for the promotion of aboveground grassland production by native large herbivores in Yellowstone National Park. Oecologia.

[19] Thomas HS. Ranchers Sing the Praises of Mob Grazing of Cattle. Beef Magazine [Internet] 2012. February 28, 2012. Available from: http://www.beefmagazine.com/pasture-range/

from grazing animals. Journal Agricutral. Sciences. 2006;**145**:81-86

ranchers-sing-praises-mob-grazing-cattle [Accessed: March 03, 2018]

[13] Frost WE, Smith EL, Ogden PR. Utilization guidelines. Rangelands. 1994;**6**:256-259

pdf [Accessed: April 13, 2018]

wg006 [Accessed: June 30, 2017]

new look at an old tool. Rangelands. 2003;**25**:43-47

range ungulates. Rangelands. 1984;**6**:261-263

April 13, 2018]

2001. p. G-4970

9781610917438

1993;**96**:157-161

Tech. Bull. 1102.1955.23 pg
