Animal Science, Department of
First Advisor
Mary E. Drewnoski
Committee Members
Daren Redfearn, Jim MacDonald, Jay Parsons
Date of this Version
12-2024
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Animal Science
Under the supervision of Professor Mary E. Drewnoski
Lincoln, Nebraska, December 2024
Abstract
Rapid conversion of historical grasslands to cropland in recent history has led to limited perennial pasture availability and an increase in cost of pasture rent. Annual forages are an alternative grazing source. Many annual forages can grow and accumulate stockpile following summer harvest of wheat. Strip grazing is often suggested to increase grazing efficiency of stockpiled forages. To evaluate this, a stockpiled mixture of annual forages were either strip grazed or grazed continuously in the fall and winter. The mixture contained oats and rapeseed in the first year and a diverse warm season annual mixture in the second. Strip grazing effectively boosted carrying capacity and gain per hectare. However, impact on individual animal performance varied. Cereal rye can be planted in the fall to offer early spring grazing. However, there is disagreement over the relationship between stocking rate and animal performance and there are no studies evaluating this in a monoculture of cereal rye. To define this relationship, growing steers rotationally grazed cereal rye in the spring at different stocking rates. Increased stocking rates decreased the amount of forage available but did not impact individual animal performance. Therefore, higher stocking rates may increase the gain per hectare. In the summer, rising temperatures and forage maturity cause a decline in cool season perennial pasture nutritive value and productivity. While warm season annual forages such as sudangrass can accumulate large amounts of biomass, there is concern over maintenance of the nutritive value over the grazing season. The inclusion of the legume sunnhemp might help to increase nutritive value of the forage. To evaluate this, a monoculture of sudangrass and a mixture of sudangrass and sunnhemp were grazed with growing steers and cow/calf pairs. Forage mass was reduced with sunnhemp inclusion, however, carrying capacity and cow/calf pair performance were not different. Marginal improvement in growing steers individual animal performance was observed with sunnhemp inclusion. These data show that with proper management, annual forages can be used to fill forage gaps experienced throughout the year.
Advisor: Mary E. Drewnoski
Comments
Copyright 2024, Shelby Davies Jenkins. Used by permission