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dc.contributor.authorBoland, Holly Terryen_US
dc.date.accessioned2014-03-14T21:09:37Z
dc.date.available2014-03-14T21:09:37Z
dc.date.issued2009-01-26en_US
dc.identifier.otheretd-02182009-115657en_US
dc.identifier.urihttp://hdl.handle.net/10919/37379
dc.description.abstractPrevious research on grazing behavior has shown that ruminants will select a mixed diet. The use of adjacent monocultures is an essential tool for determining dietary preference of forages. Much of the work to date has been conducted with white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.). Partial preference for white clover over ryegrass has been reported consistently and partial preference for legumes is thought to occur regardless of the legume and grass species being evaluated. Two forage species, tall fescue (Festuca arundinacea Schreb. or Lolium arundinaceum (Schreb.) S.J. Darbyshire) and alfalfa (Medicago sativa subsp. sativa L.), which had not been evaluated together previously as adjacent monocultures were grazed by beef steers in the present set of experiments. Steers exhibited a partial preference for alfalfa of 61 to 65% when given a choice of grazing alfalfa or tall fescue as adjacent monocultures, regardless of the ground area proportion of the two forages offered. Steers grazing tall fescue monocultures spent more time ruminating (P = 0.02) and tended to graze less time (P = 0.06) than steers in adjacent monoculture treatments. Time spent idling, number of prehensions and mastications, and bite rate were similar (P > 0.05) among treatments. Steers grazing tall fescue monocultures spent less time standing, more time lying, were less active and took fewer steps (P â ¤ 0.05) than steers in adjacent monoculture treatments. Grazing behavior was examined when alfalfa had not been in the previous diet of the steers. Cattle without previous experience grazing alfalfa spent 78% of the time grazing alfalfa, whereas after having experience grazing it they spent a lower (P = 0.04) proportion of their time grazing alfalfa (72%). Overall proportion of the day spent grazing both forages was lower (P = 0.0001) when alfalfa was novel (40%), compared to when steers were experienced grazing both forages (46%). Proportion of the day spent idling was greater (P < 0.0001) when alfalfa was novel (35%), compared to when both forages were familiar to the steers (26%). Previous research has reported that ruminants exhibit a diurnal pattern of preference by decreasing the proportion of white clover consumed from morning to late afternoon while increasing the proportion of perennial ryegrass in the diet. This is thought to be a strategy to increase fiber intake before nightfall or as a response to higher carbohydrate levels in grass in the afternoon. In the present study, proportion of grazing time in alfalfa was higher (P = 0.02) in the afternoon (76.8 %) than in the morning (72.1 %). While fiber concentration was higher in the tall fescue, carbohydrate concentrations were similar. Steers were not attempting to increase fiber intake in the afternoon in the present study. Dry matter intake of steers grazing adjacent monocultures of alfalfa and tall fescue was estimated with n-alkanes. Diet composition was estimated using n-alkanes and long chain alcohols (LCOH) in several different combinations. The use of LCOH added additional characterization of the forages, but diet composition estimates were not different (P â ¥ 0.22) than when estimated using four different n-alkanes. Laboratory analysis costs may be reduced if n-alkanes alone can adequately characterize the forages being consumed, depending on the forage species in question. Meteorological conditions impacted DMI with intake being less in hotter conditions. Steers had similar partial preferences for alfalfa over tall fescue (P = 0.13, 79% and 70% alfalfa in yr 1 and 2, respectively) even though total DMI differed between years (P = 0.002, 9.4 kg d-1 and 4.5 kg d-1 in yr 1 and 2, respectively). Lower DMI in yr 2 was attributed to hotter air temperatures. When animals are consuming two different forages as adjacent monocultures such as in the current experiments, it is important to determine the proportion of each forage in the diet before calculating DMI using odd chain n-alkanes of the forage along with a dose even chained n-alkane. Dry matter intake can be overestimated if the proportion of the forages consumed is not estimated and accounted for in the equation. This would apply to other studies utilizing mixed swards or any diet containing multiple components that differ in concentration of the n-alkane being used for DMI estimation. Analysis of n-alkane concentration should be performed on each item in the diet and the proportion of each item in the diet estimated so that the right value can be used in the calculation. Differences in marker concentrations between years also indicate the importance of analyzing those concentrations in the feed or forage at the time of fecal collection and not using values reported from previous research.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartHTBoland-Dissertation.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectDry Matter Intakeen_US
dc.subjectBeef Steersen_US
dc.subjectAlfalfaen_US
dc.subjectTall Fescueen_US
dc.subjectGrazing Behavioren_US
dc.titleSpatial Allocation of Forages and Its Impact on Grazing Behavior, Diet Selection and Dry Matter Intake of Beef Steersen_US
dc.typeDissertationen_US
dc.contributor.departmentAnimal and Poultry Sciencesen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAnimal and Poultry Sciencesen_US
dc.contributor.committeememberRook, Andrew J.en_US
dc.contributor.committeememberAbaye, Azenegashe Ozzieen_US
dc.contributor.committeememberSwecker, William S. Jr.en_US
dc.contributor.committeememberFike, John Herschelen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-02182009-115657/en_US
dc.contributor.committeecochairScaglia, Guillermoen_US
dc.contributor.committeecochairNotter, David R.en_US
dc.date.sdate2009-02-18en_US
dc.date.rdate2012-04-24
dc.date.adate2009-03-13en_US


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