Show simple item record

dc.contributor.authorTucker, Heather Ashleyen_US
dc.date.accessioned2014-03-14T20:42:48Z
dc.date.available2014-03-14T20:42:48Z
dc.date.issued2009-07-28en_US
dc.identifier.otheretd-08052009-144308en_US
dc.identifier.urihttp://hdl.handle.net/10919/34362
dc.description.abstractTwo studies were conducted to assess factors affecting estrogen excretion in dairy heifers. The objective of the first study was to quantify estrogenic activity in feces and urine during the estrous cycle. Ten non-pregnant Holstein heifers were fed the same diet for 28 d. Plasma, feces, and urine samples were collected daily. Plasma 17-β estradiol (17-β E2) was quantified with RIA and used to confirm day of estrous. Feces and urine samples from days -12, -6, -2, -1, 0, 1, 2, 6, 12 of the estrous cycle were analyzed with RIA and Yeast Estrogen Screen (YES) bioassay. Plasma 17-β E2 concentrations peaked on day of estrus, with feces and urine estrogenic excretion peaking a day after. The objective of the second study was to quantify variation in estrogenic activity in feces and urine due to increased dietary phytoestrogen content. Ten Holstein heifers were randomly assigned to treatment sequence in a two-period crossover design. Dietary treatments consisted of grass or red clover hay, and necessary supplements. Feces and urine samples were collected and pooled for analysis. Estrogenic activities of pooled samples were quantified using the YES bioassay. Estrogenic excretion in feces and urine was higher for heifers fed red clover hay. Fecal and urine samples from five heifers were analyzed using LC/MS/MS to quantify excretion of phytoestrogenic compounds. Heifers fed red clover hay excreted more equol than heifers fed grass. Identifying sources of variation in estrogenic activity of manure will aid in the development of practices to reduce environmental estrogen accumulation.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartHeatherATuckerETD.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.subjectphytoestrogenen_US
dc.subjectestrousen_US
dc.subjectestrogenen_US
dc.subjectdairy heiferen_US
dc.titleFactors affecting estrogen excretion in dairy heifersen_US
dc.typeThesisen_US
dc.contributor.departmentDairy Scienceen_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.disciplineDairy Scienceen_US
dc.contributor.committeechairKnowlton, Katharine F.en_US
dc.contributor.committeememberVoshell, J. Reese Jr.en_US
dc.contributor.committeememberAkers, Robert Michaelen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08052009-144308/en_US
dc.date.sdate2009-08-05en_US
dc.date.rdate2010-08-14
dc.date.adate2009-08-14en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record