Starch Digestion and Phosphorus Excretion in Lactating Dairy Cows

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dc.contributor.authorGuyton, Autumn Deanneen
dc.contributor.committeechairKnowlton, Katharine F.en
dc.contributor.committeememberPolan, Carl E.en
dc.contributor.committeememberPearson, Ronald E.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2014-03-14T20:44:15Zen
dc.date.adate2002-08-27en
dc.date.available2014-03-14T20:44:15Zen
dc.date.issued2002-08-08en
dc.date.rdate2003-08-27en
dc.date.sdate2002-08-26en
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
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-08262002-122603en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08262002-122603/en
dc.identifier.urihttp://hdl.handle.net/10919/34778en
dc.publisherVirginia Techen
dc.relation.haspartthesisfinal.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectphytase activityen
dc.subjectPhosphorus and nitrogen excretionen
dc.subjectstarch digestionen
dc.titleStarch Digestion and Phosphorus Excretion in Lactating Dairy Cowsen
dc.typeThesisen
thesis.degree.disciplineDairy Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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