Rotational Grazing on Rangelands: Reconciliation of Perception and Experimental Evidence
AuthorBriske, D. D.
Derner, J. D.
Brown, J. R.
Fuhlendorf, S. D.
Teague, W. R.
Havstad, K. M.
Gillen, R. L.
Ash, A. J.
Willms, W. D.
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CitationBriske, D. D., Derner, J. D., Brown, J. R., Fuhlendorf, S. D., Teague, W. R., Havstad, K. M., ... & Willms, W. D. (2008). Rotational grazing on rangelands: reconciliation of perception and experimental evidence. Rangeland Ecology & Management, 61(1), 3-17.
PublisherSociety for Range Management
JournalRangeland Ecology & Management
AbstractIn spite of overwhelming experimental evidence to the contrary, rotational grazing continues to be promoted and implemented as the only viable grazing strategy. The goals of this synthesis are to 1) reevaluate the complexity, underlying assumptions, and ecological processes of grazed ecosystems, 2) summarize plant and animal production responses to rotational and continuous grazing, 3) characterize the prevailing perceptions influencing the assessment of rotational and continuous grazing, and 4) attempt to direct the profession toward a reconciliation of perceptions advocating support for rotational grazing systems with that of the experimental evidence. The ecological relationships of grazing systems have been reasonably well resolved, at the scales investigated, and a continuation of costly grazing experiments adhering to conventional research protocols will yield little additional information. Plant production was equal or greater in continuous compared to rotational grazing in 87% (20 of 23) of the experiments. Similarly, animal production per head and per area were equal or greater in continuous compared to rotational grazing in 92% (35 of 38) and 84% (27 of 32) of the experiments, respectively. These experimental data demonstrate that a set of potentially effective grazing strategies exist, none of which have unique properties that set one apart from the other in terms of ecological effectiveness. The performance of rangeland grazing strategies are similarly constrained by several ecological variables establishing that differences among them are dependent on the effectiveness of management models, rather than the occurrence of unique ecological phenomena. Continued advocacy for rotational grazing as a superior strategy of grazing on rangelands is founded on perception and anecdotal interpretations, rather than an objective assessment of the vast experimental evidence. We recommend that these evidence-based conclusions be explicitly incorporated into management and policy decisions addressing this predominant land use on rangelands.
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Grazing systems, stocking rates, and cattle behavior in southeastern WyomingHepworth, K. W.; Test, P. S.; Hart, R. H.; Waggoner, J. W.; Smith, M. A. (Society for Range Management, 1991-05-01)Grazing systems and stocking rates are used to influence livestock grazing behavior with the intent of improving livestock and vegetation performance. In 1982, a study was initiated to determine effects of continuous, rotationally deferred, and short-duration rotation grazing and moderate and heavy stocking rates on steer gains, range vegetation, and distance traveled by and activity patterns of steers. Steers were observed from dawn to dark on 12 dates during 1983, 1984, and 1985, and activity recorded every 15 minutes. Eight steers per treatment (system X stocking rate combination) per date were observed in 1983 and 1984, and 10 per treatment in 1985. In 1984 and 1985, map locations of all steers were recorded at the same times as activity, and distance traveled summed from distances between successive map locations. In 1984, activity of 3 steers per treatment was electronically monitored during darkness. Steers grazed approximately 8.6 hr per day during daylight and 1.6 hr during darkness. Steers grazed an average of 8.9 hr/day during daylight under moderate vs 8.1 hr under heavy stocking, but stocking rate interacted with date in 1984 and grazing system in 1985. Steers traveled farther under continuous than under short-duration rotation grazing at both stocking rates in 1984, but only at the high stocking rate in 1985. Steers had to travel farther to water in the continuous pastures, and may have had to cover a greater area in an effort to select a more desirable diet, particularly under heavy stocking. These differences were not reflected in differences in gain among stocking rates or grazing systems.
Some effects of a rotational grazing treatment on cattle grazing behaviorWalker, J. W.; Heitschmidt, R. K. (Society for Range Management, 1989-07-01)Research was conducted on the effects of rotational grazing (RG) compared to continuous grazing (CG) on the behavior of cattle grazing on rangelands. Different livestock densities in the RG treatments were created by varying the size of paddocks in a 465-ha, 16-paddock, cell designed RG treatment stocked at a rate of 3.6 ha/cow/yr. Paddock sizes of 30 and 10-ha were used to simulate RG with 14 (RG-14) and 42-paddocks (RG-42), respectively. The CG treatment consisted of a 248-ha pasture stocked at 5.9 ha/cow/yr. Data were collected using vibracorders, pedometers and observation to estimate time (min/day) spent: intense grazing, search grazing, trailing, or sleeping; distance walked (km/day), and individual animal space ( m2/animal) in grazing subherds. Total grazing time did not vary among grazing treatments, but the components of total grazing (i.e., intense and search grazing) did vary among treatments. Cattle in the RG-14 paddocks spent less time search grazing compared to the ones in the other treatments presumably because the rotational grazed paddocks were more uniform because of less mixing of live and dead forage. Search grazing was highest in the RG-42 paddocks which may be due to the high stock density in this treatment coupled with an attempt to maintain individual animal space. Grazing time tended to be longer the first day in a RG-14 paddock than the last. Time spent trailing and the distance walked increased as the frequency of rotation increased among the different treatments. Sleeping was similar among grazing treatments. Individual animal space within a grazing subherd decreased as the stock density increased because of the grazing treatment.
Effects of herbage allowance on defoliation patterns of tallgrass prairieJensen, H. P.; Gillen, R. L.; McCollum, F. T. (Society for Range Management, 1990-09-01)Few studies have dealt with measuring individual plant defoliations in the context of intensive grazing management. In May, July, and August of 1987, grazing trials were conducted to quantify the effects of herbage allowance on defoliation patterns of big bluestem [Andropogon gerardii Vitman], Indiangrass [Sorghastrum nutans (L.) Nash], and little bluestem [Schizachyrium (Michx.) Nash]. Herbage allowances of 10, 20, 30, and 40 kg AUD-1 were replicated twice per trial. Tiller height, relative leaf area removed, and lrequency of defoliation were measured every 2 days over 10-day trials. Indiangrass was the most preferred species in all trials. The rate of leaf area removal increased as herbage allowance decreased. Current guidelines which call for rest periods of 30-90 days would result in light to moderate intensity defolia- tion for indiangrass at all herbage allowances. The maximum percentage of tillers grazed only once per trial ranged from 20 to 98% depending on herbage allowance, species, and trial. Selectivity between species was reduced by decreasing herbage allowance but this effect was not large until herbage allowance was below 20-25 kg AUD-1 and selectivity was never completely removed. Grazing all tillers only once in a grazing period, even within a species, is unlikely in a tallgrass prairie community. Leaf area removal was moderate the first time a tiller was defoliated and severe for later defoliations. The goal of grazing any individual tiller at no greater than moderate intensity within a grazing period would he roughly equivalent to grazing any tiller no more than once. However such a goal would require many tillers to go ungrazed.