The Modified Grazing Response Index – an improved planning tool for rotational grazing of livestock

Abstract

The Grazing Response Index (GRI) is a simple and effective grazing evaluation tool that was initially developed at Colorado State University by Floyd Reed, Roy Roath, and David Bradford in 1999. The goal of the GRI is to rapidly assess the effects of grazing and provide data to aid in the development of grazing plans for the following year. While the GRI has proven to be simple and effective grazing assessment tool, updates to its basic framework are needed to reflect recent scientific findings and broaden its applicability in grazing regions where year-round grazing is typical. One notable limitation of the GRI is that it does not account for dormant season grazing, which is common in many southwestern rangelands systems where winters are milder. As a result, we propose the Modified Grazing Response Index (MGRI), an updated version of the GRI, tailored to the needs of the southwestern United States and other areas that may have year-round grazing.