Effects of pasture and management variables on forage intake by grazing sheep Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/cn69m640v

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Grazing experiments were conducted in summer, autumn and winter to assess the effects of stock density, grazing duration, pre-grazing pasture mass and stock type on forage intake by sheep grazing at high stock densities for short durations. In summer and winter, sheep were stocked at 200 sheep/ha on 0.1 ha plots for 9 and 4 days, respectively. Total dry matter (TDM) and green dry matter (GDM) were estimated each day by clipping 0.2 m² plots to ground level. In autumn, ewes and lambs separately grazed 0.333 ha pastures at stock densities of 270, 540 or 810 sheep/ha for 1, 2, or 3 days. Pre- and post-grazing TDM were estimated with a single probe capacitance meter. The percent GDM of TDM was estimated using a spectophotometer. In each study TDM and GDM pasture mass were analyzed using a non-linear (negative exponential) multi-variate regression model. Intake was estimated from results of pasture mass analysis. In autumn, ewes and lambs consumed similar amounts of TDM, but ewes consumed 43% more GDM (P<.05) than lambs; differences between treatments at the same grazing pressure (stock density X grazing duration) in intake of both TDM and GDM were not significantly different. In all analyses regression coefficients for grazing pressure, i.e. instantaneous rates of forage decline per stock day, were significant (P<.01). Instantaneous rates per stock day in TDM analyses were 0.0007, 0.0001 and 0.0002, and in GDM analyses were 0.0019, 0.0003 and 0.0010 for summer, autumn and winter, respectively. A simulation model was also developed which predicted intake of GDM and DDM by sheep grazing at high stock densities for short durations. Model predictions of intake agreed favorably with summer and winter observations, but the model overestimated intake during autumn. In agreement with previous studies, the model predicted intake would increase at a decreasing rate as forage allowance (kg/sheep/day) increased.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Rejected by Patricia Black(patricia.black@oregonstate.edu), reason: Replace file. on 2013-05-02T14:58:47Z (GMT)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-06-04T16:04:14Z (GMT) No. of bitstreams: 1 LewisRobertD1990.pdf: 1128466 bytes, checksum: a9227c6c0ae82c80a2bdc846c1a60843 (MD5)
  • description.provenance : Made available in DSpace on 2013-06-04T16:04:14Z (GMT). No. of bitstreams: 1 LewisRobertD1990.pdf: 1128466 bytes, checksum: a9227c6c0ae82c80a2bdc846c1a60843 (MD5) Previous issue date: 1989-06-23
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-05-01T21:45:31Z (GMT) No. of bitstreams: 1 LewisRobertD1990.pdf: 1123572 bytes, checksum: bd54fb73190c730be92de6f04762d85c (MD5)
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2013-05-01T18:20:36Z No. of bitstreams: 1 LewisRobertD1990.pdf: 1123572 bytes, checksum: bd54fb73190c730be92de6f04762d85c (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-05-08T15:30:05Z (GMT) No. of bitstreams: 1 LewisRobertD1990.pdf: 1128466 bytes, checksum: a9227c6c0ae82c80a2bdc846c1a60843 (MD5)
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2013-05-02T15:05:57Z No. of bitstreams: 1 LewisRobertD1990.pdf: 1128466 bytes, checksum: a9227c6c0ae82c80a2bdc846c1a60843 (MD5)

Relationships

In Administrative Set:
Last modified: 08/04/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items