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dc.contributor.authorVargas Jurado, Napoleonen_US
dc.date.accessioned2014-03-14T20:42:29Z
dc.date.available2014-03-14T20:42:29Z
dc.date.issued2012-07-24en_US
dc.identifier.otheretd-08012012-122210en_US
dc.identifier.urihttp://hdl.handle.net/10919/34299
dc.description.abstractEstimating feed efficiency in grazing environments is challenging due to difficulties in quantifying food intakes and diet choices in free-grazing animals. The plant-wax marker technique may be a useful tool to redress this problem. However, its reliability needs to be validated before its wider application. This study was designed to assess the reliability of plant-wax markers for estimating botanical composition of test diets, and diet choices in beef cattle, and provided opportunities to evaluate efficiency in growing heifers. To test estimation of botanical composition, samples of red clover and fescue hay were mixed to form test diets containing 0-100% of either forage. To test estimation of diet choices, 24 heifers from large and moderate frame size lines were evaluated at two instances. Cubed red clover and fescue hays were offered ad libitum. After an acclimation period, feed intakes and body weights were collected for 10 days; fecal samples were collected for the final 5 days. Hydrocarbons and alcohols were quantified with gas chromatography. Estimates were based on least squares. Operator expertise affected measured concentrations of shorter-chained n-alkanes (P<0.041) and long-chain alcohols (P<0.02). Still, overall reliability of the technique was unaffected. Large and moderate framed animals did not differ in efficiency (P>0.05), although large framed animals had increased red clover intakes (P<0.01). Once corrected for fecal losses of n-alkanes, diet choices were estimated accurately. Plant-wax markers provided reliable estimates of botanical composition of diets, and diet choices of animals, suggesting it is a valuable tool to assess efficiencies of grazing cattle.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartVargas_N_T_2012.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.subjectfeed efficiencyen_US
dc.subjectdiet choiceen_US
dc.subjectBeef cattleen_US
dc.subjectgrazingen_US
dc.subjectplant-wax markersen_US
dc.titleAssessing the reliability of plant-wax markers to delineate diet choice and feed efficiency in beef heifersen_US
dc.typeThesisen_US
dc.contributor.departmentAnimal and Poultry Sciencesen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAnimal and Poultry Sciencesen_US
dc.contributor.committeechairLewis, Ronald M.en_US
dc.contributor.committeememberMcCann, Mark A.en_US
dc.contributor.committeememberTracy, Benjamin Franklinen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08012012-122210/en_US
dc.date.sdate2012-08-01en_US
dc.date.rdate2012-08-21
dc.date.adate2012-08-21en_US


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