Pasture Growth, Production, and Quality Under Rotational and Continuous Grazing Management

Abstract

Management intensive rotational grazing (MIRG) is an expanding practice among dairy farmers in the Upper Midwest Despite the high productivity associated with MIRG pastures, many acres of unmanaged, continuously grazed pastures still exist. Our goal was to document relationships between forage growth, production, and quality in rotational and continuous grazing systems and to evaluate the role that management plays in the productivity of these pastures. Forages were monitored under farmer management on three MIRG dairy farms and on three continuously grazed pastures (CON) on conventional livestock farms in 1994 and 1995. Evaluation of the results was complicated by the range of conditions and management practices that characterized the study's participants. As is typical for this region, CON pastures in this study were unmanaged. In contrast, MIRG pastures were monitored daily by their owners and sward health was maintained through movement of the herd and such practices as interseeding legumes. Forage mass for MIRG pastures was greater than CON every week of the 24-wk grazing season, averaging 1763 lb/acre for ready-to-graze MIRG paddocks vs. 850 lb/acre for CON. Crude protein averaged 16.6% for MIRG vs. 15.3% for CON. Seasonal average ADF values were 34.2% for MIRG and 34.1% for CON. Average NDF values were 53.4% for MIRG and 56.8% for CON. Forage mass between 1300 and 1900 lb/acre appeared to provide a balance between yield and quality on MIRG pastures. Cooperating farmers most often chose to graze paddocks at this level. For CON, forage quality decreased as forage biomass increased. Ready-to-graze MIRG paddocks had significantly higher quality than CON pastures at equivalent levels of forage biomass. It was not possible in this study to isolate individual management practices and test them separately, so no one factor can be viewed as responsible for the differences we observed. Indeed, these differences probably are the result of the interaction among several management practices on MIRG farms and the lack of pasture management on CON farms.