Thesis
The effects of spring cattle grazing on the nutritional ecology of mule deer (Odocoileus hemionus) in Eastern Washington
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/101997
Abstract
In some grassland communities, livestock grazing may reduce residual grass and promote younger, more nutritious forages. However, no study has yet directly examined how spring cattle grazing affect the quantity and quality of forage available to mule deer (Odocoileus hemionus). Therefore, we created 2-sets of 3 plots of paired grazing treatments using electric fence exclosures within 3 pastures in bluebunch wheatgrass (Pseudoroegneria spicata) communities in southeastern Washington. In each grazed/ungrazed plot, we sampled the biomass and nutritional quality of all plants by species in both spring and fall. We constructed temporary pens in each grazed/ungrazed plot and measured diet composition selected by 4 tractable mule deer in each pen using bite count methods, collected representative diets for each deer in each plot, and analyzed them for digestible nitrogen and protein in spring and fall. In spring and fall, grazed pastures had 40% less total biomass, and significantly less perennial grasses and perennial forbs. As a consequence, across seasons, deer consumed about 40% less perennial and annual forbs, and 30% more perennial grasses grazed pens. Using Ivlev's selectivity index, we found that deer selected for annual forbs and subshrubs and avoided perennial and annual grasses. The dry matter digestibility and digestible energy of the deer's diets was similar between grazed and ungrazed plots, but digestible protein was higher in grazed plots in 2 pastures and lower in the third on than on grazed plots. Deer cropped larger bites (g/bite) in ungrazed plots than grazed plots in fall, had a higher instantaneous intake (g/min) in ungrazed plots in one pasture, and had a higher daily dry matter intake (g/day) and daily digestible energy intake (kJ/day) in ungrazed than grazed plots across pastures and seasons. Because biomass of forage was reduced up to 50% in grazed plots, while nutritional quality of forages, including P. spicata increased modestly, if at all, nutritional carrying capacity for deer was lower in grazed than ungrazed plots in 2 of the 3 pastures. Our results suggest that moderate spring cattle grazing in dry-stony ecological sites reduced the amount of digestible nutrients available to mule deer during the year of grazing.
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Details
- Title
- The effects of spring cattle grazing on the nutritional ecology of mule deer (Odocoileus hemionus) in Eastern Washington
- Creators
- Sara Jane Wagoner
- Contributors
- Lisa A. Shipley (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Agricultural, Human, and Natural Resource Sciences, College of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525083101842
- Language
- English
- Resource Type
- Thesis