When it comes to native grass pastures, does rotational grazing itself really benefit the grass? With any system, the problem is not the cow, but the manager
Most, if not all, range management professionals present rotational grazing as the definitive answer to virtually any range management problem they face. Briske and Brown (2011) noted this situation has persisted since the turn of the 20th century when American range ecologists and government agencies sought effective ways to improve the range health of rangelands in the western United States.
Subsequently, Canadian officials adopted the same recommendations made by the Americans even though there was not any solid scientific evidence to support the American’s conclusions.
Briske et. al. (2008) concluded the commonly held perception, that rotational gazing is superior to season-long continuous grazing, is due more to perception and the use of anecdotal evidence than application of scientific evidence.
The arguments presented by supporters of short-duration grazing and conventional rotational grazing provide some good examples of this phenomenon. For those of you who disagree, think about it for a minute. Every grazing seminar you have attended (or article you have read) in the past 20 years has presented examples of producers who have “saw the light,” cross-fenced their pastures and now are diehard converts to rotational grazing (praise God and pass the fencing pliers).
Briske, et. al. (2008) reached this conclusion after reviewing a number of grazing trials conducted throughout North America over the past 50 years. The trials they compared looked at three variables: plant production (lb./acre), animal production per area (lb./acre) and animal production per head (lb./hd). In 23 grazing trials comparing plant production, season-long continuous grazing was superior to or equal to rotational grazing in 20 trials. In 38 grazing trials comparing animal production per head, season-long continuous grazing was superior to or equal to rotational grazing in 35 trials. In 32 grazing trials comparing animal production per area, season-long continuous grazing was superior to or equal to rotational grazing in 27 trials.
These comparisons led the authors to believe it was not the type of grazing system but the quality of resource management that determined the impact of grazing.
In their review of the research on grazing systems, Bailey and Brown (2011) also came to the conclusion rotational grazing does not deliver on its promises. These authors concluded rotational grazing systems do not significantly alter what plants animals will graze despite an increase in animal density. They argued a significant change in selectivity only occurs at a combination of high grazing densities and high stocking rates.
However, they noted the combination of high grazing densities and high stocking rates invariably leads to lower animal performance (net return, animal gain, etc.). They also suggest rotational grazing systems do little to improve livestock distribution on the landscape. Instead, the authors suggest implementing a management system that uses a moderate stocking rate and focuses on managing key elements of the landscape (such as riparian areas).
Rotational grazing is often regarded a panacea for most grazing issues. In many cases (like short-duration grazing (SDG) grazing), it’s regarded as a quick-fix, one-size-fits-all solution. Invariably, these individuals consider rotational grazing superior to season-long continuous grazing by offering evidence based anecdotal evidence or the belief rotational grazing involves more sophisticated range management.
However, upon reviewing the scientific evidence, this is not the case. The research clearly shows the type of grazing system has very little impact on the success or failure of a range management plan.
TWO KEY FACTORS
Range managers often overlook two key factors when it comes to designing and implementing grazing plans. The first is precipitation. If there is insufficient moisture during the growing season, there will not be any grass; making even the most sophisticated grazing system redundant.
The second factor is management. Research clearly demonstrates the improvements to range health associated with rotational management strategies can be attributed to an improvement in management. When producers adopt rotational grazing systems, they begin paying more attention to animal grazing behaviour, range ecology and other factors. If the same principles are applied to a season-long continuous system, the same improvements in range health are achieved. However, research shows a season-long continuous system shows higher net returns and animal performance than all rotational grazing systems.
Sustainable management of native grass in not dependant on the type of grazing system the range manager uses. Instead, sustainable management depends more upon the landowner’s commitment to understanding the ecology of the ecosystems he manages and then applying sound range management principle, such as the use of sustainable stocking rates and adequate livestock distribution techniques, to achieve desired ecological and economic goals.
I would encourage you, the reader to read these papers. If you are in interested, you can Google the titles.
D.D. Briske, J.D. Derner, J.R. Brown, S.D. Fuhlendorf, W.R. Teague, K.M. Havstad, R.L. Gillen, A.J. Ash, and W.D. Willms. 2008. Rotational Grazing on Rangelands: Reconciliation of Perception and Experimental Evidence Rangeland Ecol Manage. 61:3-17.
D.W. Bailey and J.R. Brown. 2011. Rotational Grazing Systems and Livestock Grazing Behavior in Shrub-Dominated Semi-Arid and Arid Rangelands. Rangeland Ecol Manage. 64:1-9.
D.D. Briske, N.F. Sayre, L. Huntsinger, M. Fernandez-Gimenez, B. Budd, and J.D. Derner. 2011. Origin, Persistence, and Resolution of the Rotational Grazing Debate: Integrating Human Dimensions Into Rangeland Research. Rangeland Ecol Manage. 64:325-334. †