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dc.contributor.authorGuyton, Autumn Deanneen_US
dc.date.accessioned2014-03-14T20:44:15Z
dc.date.available2014-03-14T20:44:15Z
dc.date.issued2002-08-08en_US
dc.identifier.otheretd-08262002-122603en_US
dc.identifier.urihttp://hdl.handle.net/10919/34778
dc.description.abstractThe effects of starch and phosphorus (P) source on P partitioning and ruminal phytase activity were evaluated in eight lactating cows (113 DIM). Four cows were ruminaly cannulated. Cows were randomly assigned to treatments in a duplicated 4x4 Latin square with four, 18-d periods. Diets included dry ground corn (DG) or steam flaked corn (SF), with a no supplemental P (low P diet; 0.34% P) or supplemental purified phytic acid (PA; 0.45% P) to provide additional P from an organic source. Total collection of milk, urine, feces, and feed were sampled each period, while rumen fluid was sampled on d 18. Excretion of feces, urine, P, and N was lower in cows fed SF than in cows fed DG. Milk yield was unaffected by diet despite a lower DMI by cows fed SF. Cows fed SF tended to have a higher feed efficiency and lower milk urea nitrogen (MUN) concentration than cows fed DG. Rumen pH was unaffected by diet, but milk fat content was lower for cows fed SF. Milk yield, DMI, and feed efficiency were not affected by PA. Cows fed PA had increased P intake and excretion, but a lower milk P as a percentage of intake compared with cows fed the low P diet. An interaction of starch source and P source was observed for ruminal phytase activity. Altering dietary sources of starch and P offers opportunity to improve P availability and reduce manure nutrient excretion.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartthesisfinal.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.subjectphytase activityen_US
dc.subjectPhosphorus and nitrogen excretionen_US
dc.subjectstarch digestionen_US
dc.titleStarch Digestion and Phosphorus Excretion in Lactating Dairy Cowsen_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.committeememberPolan, Carl E.en_US
dc.contributor.committeememberPearson, Ronald E.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08262002-122603/en_US
dc.date.sdate2002-08-26en_US
dc.date.rdate2003-08-27
dc.date.adate2002-08-27en_US


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