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dc.contributor.authorForrest, James Walteren_US
dc.date.accessioned2014-03-14T20:37:34Z
dc.date.available2014-03-14T20:37:34Z
dc.date.issued2003-05-16en_US
dc.identifier.otheretd-05192003-133446en_US
dc.identifier.urihttp://hdl.handle.net/10919/32980
dc.description.abstractRapid rearing of dairy heifers during late prepuberty has been linked to impairments in mammary development and reductions in milk yield. Our objective was to determine how varying energy intakes between 2 and 14 wk of age affect mammary parenchymal development. At 2 wk of age, Holstein calves were assigned to 1 of 4 treatments (HH, HL, LH, and LL) with 2 levels of energy intake (High or Low) and 2 periods of growth (2 to 8 and 8 to 14 wk of age). At 14 wk, parenchyma at the stromal interface, mid-gland, and above the cistern were collected, fixed, and embedded in paraffin. Digital images of stained sections were used to determine tissue composition (% epithelium, lumen, and stroma). Immunochemistry revealed estrogen receptor (ER) and Ki67 (nuclear proliferation antigen) positive cells, type IV collagen, fibronectin (FN), and laminin. Images representing 4 increasing grades were used to quantify ECM protein deposition. Lumenal and stromal areas were 3.5 ± 1.4% higher (p<0.01) and 4.0 ± 1.7% lower (p<0.01), respectively, in HH and HL heifers. Ki67 labeling in terminal ductular units and subtending ducts was 2.1 ± 0.8% (p<0.01) and 1.4 ± 0.7% (p<0.05) lower for the same feeding level combination. FN deposition was also increased (p<0.05) in HH and HL heifers. High rates of gain between 2 and 14 wk of age resulted in greater lumenal area and reduced cell proliferation in mammary parenchyma at 14 wk of age. Changes in FN deposition could have mediated growth differences.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartTHESIS.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.subjectestrogen receptoren_US
dc.subjectheifersen_US
dc.subjectmammaryen_US
dc.subjectextracellular matrixen_US
dc.subjectnutritionen_US
dc.titleEffects of varying energy intakes on mammary growth and development in prepubertal 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.committeechairAkers, Robert Michaelen_US
dc.contributor.committeememberHoward, Rick Daleen_US
dc.contributor.committeememberPearson, Ronald E.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05192003-133446/en_US
dc.date.sdate2003-05-19en_US
dc.date.rdate2003-06-09
dc.date.adate2003-06-09en_US


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