In 2nd Review: Rotational & Continuous Grazing Meta-Analysis

Debates over the effectiveness and benefits of a variety of grazing systems abound, and have been ongoing for well over a century. In 2008, Briske et al. (see Rotational Grazing on Rangelands: Reconciliation of Perception and Experimental Evidence) published a paper addressing this issue, concluding that there is no significant difference between “rotational” or “continuous” grazing systems…

Continuous versus rotational grazing, again: Another perspective from meta-analysis

In an effort to close the continuous- (CG) versus rotational-grazing (RG) debate that has occupied rangeland management discussions for over a century, Briske et al. (2008) reviewed 47 peer-reviewed journal articles from 1950-2007 comparing CG with various RG systems. The authors used vote counting to tally the number of studies that found significantly greater, equal, or lower production for CG relative to RG for three response variables: animal production (AP, both in kg/head and kg/ha) and plant production (PP, kg /ha). They concluded grazing research does not show these two systems produce different results, and as such advocates for RG are likely relying on anecdotal observations. However, a quantitative meta-analysis of the same studies revealed differences not previously detected by the vote-counting method. Animal production was on average higher for CG than RG, but multivariate regression instances in which RG may outperform CG. Anecdotal observations that animal production may be higher under RG than CG in highly stochastic or arid climates was supported at the ranch scale (large scale, commercial-sized operations), but not at the research scale (small-scale, plots-scale studies), suggesting size of operation/observation plays an important role in detection of productivity outcomes. Increased seasonality of temperature was also strongly significant, showing higher productivity for RG systems relative to CG as seasonality increased. However, limited numbers of large-scale experiments in arid environments (8) included in the 2008 paper make conclusive statements regarding grazing system effectiveness difficult. These results suggest the possibility of RG outperforming CG for animal production at large scales in less constant, arid climates – where most livestock grazing occurs.