Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Wildland Resources

Department name when degree awarded

Wildland Sciences

Committee Chair(s)

Frederick D. Provenza


Frederick D. Provenza


Juan J. Villalba


Randall D. Wiedmeier


Carl D. Cheney


Kevin Welch


During the past several decades, people worldwide have expressed a growing interest in reconstructing ecosystems to enhance ecological, economic, and social values. Yet, to do so we must find ways to enhance biodiversity, environmental quality and the sustainability of grazing lands. In all these instances, plants are the glue that binds soils, water, herbivores, and people. However, monocultures or simple grass-legume mixtures are not always ideal for intensively managed pastures due to their seasonality, susceptibility to pests, and monotony of plant nutrients and toxins. All plants contain so-called “toxins,” more appropriately referred to as secondary compounds, which are crucial in plant defense and survivability. High doses of secondary compounds can cause decreases in animal intake, production, and health, dramatically impacting the efficiency and cost of livestock production and land management. Yet, diverse mixtures of plants may provide many benefits monocultures cannot. Complementarities among plant secondary compounds may actually enhance animal intake, efficiency and health when animals eat plants that contain higher levels of secondary compounds (i.e. toxins).

With my PhD program, I sought to understand how complementary interactions among the secondary compounds alkaloids, tannins, and saponins influenced livestock grazing behavior and the further implications of these interactions for land and animal management. This research will help us better understand the ability of herbivores to use complementary forages to enhance the biodiversity of landscapes and productivity of herbivores while at the same time decreasing our reliance on herbicides and insecticides to protect plants. Complementary foods and sequence in animal grazing systems may prove fundamental in the upcoming transition from high fossil fuel inputs to more sustainable alternatives in animal and land management.




This work made publicly available electronically on May 10, 2012.