INTERACTION OF PLANT SPECIES DIVERSITY ON GRAZING BEHAVIOR AND PERFORMANCE OF LIVESTOCK GRAZING TEMPERATE REGION PASTURES

Authors: Soder, Kathy; ROOK, A - INST. OF GRASSLAND&ENVIR; Sanderson, Matt; Goslee, Sarah

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2006
Publication Date: 2/6/2007
Citation: Soder, K.J., Rook, A.J., Sanderson, M.A., Goslee, S.C. 2007. Interaction of Plant Species Diversity on Grazing Behavior and Performance of Livestock Grazing Temperate Region Pastures. Crop Science 47:416-425

Interpretive Summary: Pastures containing multiple plant species have been shown to have greater plant productivity than pastures planted with a single plant species. Grazing animals are key drivers of pasture species diversity through selective grazing, trampling, and excretion patterns. However, it has not been fully determined how plant species diversity affects animal productivity. A two-year study conducted by USDA-ARS and The Pennsylvania State University reported no differences in dry matter intake, grazing behavior, or milk production of dairy cows grazing different levels of plant species diversity. The cows maintained a high level of milk production and intake on all forage mixtures and showed an ability to adapt to a variety of forage species. Although animal productivity was not impacted, increased plant species mixtures produced more forage in a dry year and had reduced weed invasion compared to a simple mixture. This invited review summarizes the current knowledge regarding the importance of plant species diversity on performance of livestock grazing temperate region pastures, including mechanisms by which grazing animals alter plant species diversity, mechanisms of diet choice, effects of plant species diversity on animal performance, and implications to sustainable domestic livestock grazing systems. A greater knowledge and understanding of the complex interactions occurring between animals and plants will lead to new opportunities to develop environmentally and economically sustainable grazing systems.

Technical Abstract: This review summarizes the current knowledge regarding the importance of plant species diversity on performance of livestock grazing temperate region pastures. As dairy and livestock producers seek less capital-intensive production systems, emphasis has been placed on low-input pasture systems that rely on complex species mixtures to produce forage. Increased plant species diversity has been linked to improvements in ecosystem function, however, the effects of increased plant species diversity on macro-herbivore productivity (and vice versa) have not yet been well explored. This review covers mechanisms by which macro-herbivores alter plant species diversity, mechanisms of diet choice, effects of plant species diversity on herbivore performance, and implications to sustainable domestic livestock grazing systems. While grazing behavior research conducted over the last several decades has led to advances in the understanding of plant-herbivore interactions, improved knowledge of these interactions is crucial for predicting animal performance, as well as evaluating the impact of herbivores on the dynamics of mixed swards. Recently more effort is being made to understand how characteristics of the individual species in swards affect the bite mass and intake rate of the grazing animals, and conversely, how grazing behavior affects sward production and diversity which will lead to recommendations for creating and maintaining both desired pasture diversity and optimum animal performance. A greater knowledge and understanding of the complex interactions occurring between herbivores and the sward will lead to new opportunities to develop environmentally and economically sustainable grazing systems.