{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/36862"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/36862","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Quantifying the Effects of Microbial Phytase and Diet Acidity on Ca and P Utilization by Weanling Pigs","abstract":"Five experiments were conducted, utilizing 512 crossbred weanling pigs to determine the P (Exp. 1) and Ca (Exp. 2 and 3) equivalency values of microbial phytase based on performance, rib mineralization and P and Ca digestibility estimates, and to investigate the possible interactions of phytase and citric acid (Exp. 4 and 5). In Exp. 1, adding phytase to low P diets linearly increased ADG (P < .001), rib shear force (P < .01), shear energy (P < .02), ash weight (P < .001) and ash percent (P < .001), Ca (P < .001) and P (P < .001) digestibility and digestible Ca (P < .001) and P (P <.001). Added P linearly increased ADG (P < .003), rib shear force (P < .003) shear energy (P < .001), ash weight (P < .001) and ash percent (P < .01), Ca (P < .02) and P (P < .001) digestibility and digestible Ca (P < .02) and P (P <.001). Based on phytase and P linear or nonlinear response equations for ADG, rib shear force, shear energy, and ash weight, P digestibility, and digestible P, the average equivalency of 500 U/kg of phytase was .78 g of P per kg of diet. In Exp. 2, dietary addition of phytase linearly increased rib ash % (P < .03), Ca (P < .001) and P (P < .001) digestibilities, and digested Ca (P < .001) and P (P < .001), but had no effect (P > .10) on ADG and rib shear force and ash weight. Added Ca linearly increased ADG (wk 3-4, P < .04), and rib shear force (P < .001), ash percentage (P < .001) and ash weight (P < .01), and digested Ca (P < .001), but P digestibility (P = .07) and digested P (P = .08) were numerically decreased. In Exp. 3, added phytase linearly increased ADG (wk 3-4, P < .002), feed efficiency (wk 3-4, P < .02), rib ash weight (P < .001), Ca total tract digestibility (P < .001), and Ca (P < .001) and P (P < .001) ileal digestibilities. Added Ca linearly increased ADG (wk 3-4, P < .02), feed efficiency (wk 3-4, P < .01), rib ash percentage (P < .001) and ash weight ( P < .001), shear force (P < .03) and energy (P < .008), and total tract (P < .001) and ileal (P < .001) digestible Ca. Based on phytase and Ca linear or nonlinear response equations for ADG in wk 3-4, measurements of rib mineralization, and digestible Ca, 500 U of microbial phytase was estimated to be equivalent to 1.08 g and .78 g of Ca in Exp. 2 and 3, respectively. In Exp. 4 and 5, dietary phytase addition linearly increased rib shear force (P < .004 and P < .02), shear energy (P < .001), dry bone weight (P < .001), ash weight (P < .001) and ash percent (P < .001). Calcium (P < .001) and P (P < .001) digestibilities were also improved in both experiments when phytase was added. Addition of citric acid in both experiments, reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved ADG (P < .05), feed efficiency (P < .04) and Ca digestibility (P < .05) in Exp. 4, but decreased Ca digestibility in Exp. 5 and had no effect on performance. In Exp. 5, the addition of 2.0% citric acid to the diet supplemented with 500 U/kg of phytase caused a decrease (P < .04) in the phytase activity recovered in the stomach digesta resulting in a phytase by citric acid interaction (P < .02). In summary, the addition of 500 U/kg microbial phytase to weanling pig diets, causes the release of approximately .78 g of P and .93 g of Ca, thus decreasing the need for supplemental P and Ca. The addition of citric acid to phytase supplemented diets does not appear to enhance the efficacy of microbial phytase based on the results of these studies.","abstract_html":"Five experiments were conducted, utilizing 512 crossbred weanling pigs to determine the P (Exp. 1) and Ca (Exp. 2 and 3) equivalency values of microbial phytase based on performance, rib mineralization and P and Ca digestibility estimates, and to investigate the possible interactions of phytase and citric acid (Exp. 4 and 5). In Exp. 1, adding phytase to low P diets linearly increased ADG (P < .001), rib shear force (P < .01), shear energy (P < .02), ash weight (P < .001) and ash percent (P < .001), Ca (P < .001) and P (P < .001) digestibility and digestible Ca (P < .001) and P (P <.001). Added P linearly increased ADG (P < .003), rib shear force (P < .003) shear energy (P < .001), ash weight (P < .001) and ash percent (P < .01), Ca (P < .02) and P (P < .001) digestibility and digestible Ca (P < .02) and P (P <.001). Based on phytase and P linear or nonlinear response equations for ADG, rib shear force, shear energy, and ash weight, P digestibility, and digestible P, the average equivalency of 500 U/kg of phytase was .78 g of P per kg of diet. In Exp. 2, dietary addition of phytase linearly increased rib ash % (P < .03), Ca (P < .001) and P (P < .001) digestibilities, and digested Ca (P < .001) and P (P < .001), but had no effect (P > .10) on ADG and rib shear force and ash weight. Added Ca linearly increased ADG (wk 3-4, P < .04), and rib shear force (P < .001), ash percentage (P < .001) and ash weight (P < .01), and digested Ca (P < .001), but P digestibility (P = .07) and digested P (P = .08) were numerically decreased. In Exp. 3, added phytase linearly increased ADG (wk 3-4, P < .002), feed efficiency (wk 3-4, P < .02), rib ash weight (P < .001), Ca total tract digestibility (P < .001), and Ca (P < .001) and P (P < .001) ileal digestibilities. Added Ca linearly increased ADG (wk 3-4, P < .02), feed efficiency (wk 3-4, P < .01), rib ash percentage (P < .001) and ash weight ( P < .001), shear force (P < .03) and energy (P < .008), and total tract (P < .001) and ileal (P < .001) digestible Ca. Based on phytase and Ca linear or nonlinear response equations for ADG in wk 3-4, measurements of rib mineralization, and digestible Ca, 500 U of microbial phytase was estimated to be equivalent to 1.08 g and .78 g of Ca in Exp. 2 and 3, respectively. In Exp. 4 and 5, dietary phytase addition linearly increased rib shear force (P < .004 and P < .02), shear energy (P < .001), dry bone weight (P < .001), ash weight (P < .001) and ash percent (P < .001). Calcium (P < .001) and P (P < .001) digestibilities were also improved in both experiments when phytase was added. Addition of citric acid in both experiments, reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved ADG (P < .05), feed efficiency (P < .04) and Ca digestibility (P < .05) in Exp. 4, but decreased Ca digestibility in Exp. 5 and had no effect on performance. In Exp. 5, the addition of 2.0% citric acid to the diet supplemented with 500 U/kg of phytase caused a decrease (P < .04) in the phytase activity recovered in the stomach digesta resulting in a phytase by citric acid interaction (P < .02). In summary, the addition of 500 U/kg microbial phytase to weanling pig diets, causes the release of approximately .78 g of P and .93 g of Ca, thus decreasing the need for supplemental P and Ca. The addition of citric acid to phytase supplemented diets does not appear to enhance the efficacy of microbial phytase based on the results of these studies.","abstract_has_math":false,"creators":["Radcliffe, John Scott"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Animal and Poultry Sciences","degree_department":"Animal and Poultry Sciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Kornegay, Ervin T."],"committee_members":["Webb, Kenneth E. Jr.","Harper, Allen F."],"year":1997,"date_issued":"1997-06-27","date_published":"1997-06-27","updated_at":"2026-07-22T22:18:41Z","subjects":["Rib Mineralization","Pigs","Phytase","Phosphorus","Calcium","Citric Acid"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-62597-112336"],"render_values":[{"text":"etd-62597-112336","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/36862","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Kornegay, Ervin T."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Webb, Kenneth E. Jr.","Harper, Allen F."]},{"key":"dc:contributor.department","label":"Department","values":["Animal and Poultry Sciences"]},{"key":"dc:creator","label":"Author","values":["Radcliffe, John Scott"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:52:03Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:52:03Z","2012-04-12"]},{"key":"dc:date.issued","label":"Date","values":["1997-06-27"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Animal and Poultry Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Rib Mineralization","Pigs","Phytase","Phosphorus","Calcium","Citric Acid"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-62597-112336"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/36862"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Five experiments were conducted, utilizing 512 crossbred weanling pigs to determine the P (Exp. 1) and Ca (Exp. 2 and 3) equivalency values of microbial phytase based on performance, rib mineralization and P and Ca digestibility estimates, and to investigate the possible interactions of phytase and citric acid (Exp. 4 and 5). In Exp. 1, adding phytase to low P diets linearly increased ADG (P < .001), rib shear force (P < .01), shear energy (P < .02), ash weight (P < .001) and ash percent (P < .001), Ca (P < .001) and P (P < .001) digestibility and digestible Ca (P < .001) and P (P <.001). Added P linearly increased ADG (P < .003), rib shear force (P < .003) shear energy (P < .001), ash weight (P < .001) and ash percent (P < .01), Ca (P < .02) and P (P < .001) digestibility and digestible Ca (P < .02) and P (P <.001). Based on phytase and P linear or nonlinear response equations for ADG, rib shear force, shear energy, and ash weight, P digestibility, and digestible P, the average equivalency of 500 U/kg of phytase was .78 g of P per kg of diet. In Exp. 2, dietary addition of phytase linearly increased rib ash % (P < .03), Ca (P < .001) and P (P < .001) digestibilities, and digested Ca (P < .001) and P (P < .001), but had no effect (P > .10) on ADG and rib shear force and ash weight. Added Ca linearly increased ADG (wk 3-4, P < .04), and rib shear force (P < .001), ash percentage (P < .001) and ash weight (P < .01), and digested Ca (P < .001), but P digestibility (P = .07) and digested P (P = .08) were numerically decreased. In Exp. 3, added phytase linearly increased ADG (wk 3-4, P < .002), feed efficiency (wk 3-4, P < .02), rib ash weight (P < .001), Ca total tract digestibility (P < .001), and Ca (P < .001) and P (P < .001) ileal digestibilities. Added Ca linearly increased ADG (wk 3-4, P < .02), feed efficiency (wk 3-4, P < .01), rib ash percentage (P < .001) and ash weight ( P < .001), shear force (P < .03) and energy (P < .008), and total tract (P < .001) and ileal (P < .001) digestible Ca. Based on phytase and Ca linear or nonlinear response equations for ADG in wk 3-4, measurements of rib mineralization, and digestible Ca, 500 U of microbial phytase was estimated to be equivalent to 1.08 g and .78 g of Ca in Exp. 2 and 3, respectively. In Exp. 4 and 5, dietary phytase addition linearly increased rib shear force (P < .004 and P < .02), shear energy (P < .001), dry bone weight (P < .001), ash weight (P < .001) and ash percent (P < .001). Calcium (P < .001) and P (P < .001) digestibilities were also improved in both experiments when phytase was added. Addition of citric acid in both experiments, reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved ADG (P < .05), feed efficiency (P < .04) and Ca digestibility (P < .05) in Exp. 4, but decreased Ca digestibility in Exp. 5 and had no effect on performance. In Exp. 5, the addition of 2.0% citric acid to the diet supplemented with 500 U/kg of phytase caused a decrease (P < .04) in the phytase activity recovered in the stomach digesta resulting in a phytase by citric acid interaction (P < .02). In summary, the addition of 500 U/kg microbial phytase to weanling pig diets, causes the release of approximately .78 g of P and .93 g of Ca, thus decreasing the need for supplemental P and Ca. The addition of citric acid to phytase supplemented diets does not appear to enhance the efficacy of microbial phytase based on the results of these studies."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Quantifying the Effects of Microbial Phytase and Diet Acidity on Ca and P Utilization by Weanling Pigs"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Kornegay, Ervin T."],"dc:contributor.committeemember":["Webb, Kenneth E. Jr.","Harper, Allen F."],"dc:contributor.department":["Animal and Poultry Sciences"],"dc:creator":["Radcliffe, John Scott"],"dc:date.accessioned":["2014-03-14T20:52:03Z"],"dc:date.available":["2014-03-14T20:52:03Z","2012-04-12"],"dc:date.issued":["1997-06-27"],"dc:description.abstract":["Five experiments were conducted, utilizing 512 crossbred weanling pigs to determine the P (Exp. 1) and Ca (Exp. 2 and 3) equivalency values of microbial phytase based on performance, rib mineralization and P and Ca digestibility estimates, and to investigate the possible interactions of phytase and citric acid (Exp. 4 and 5). In Exp. 1, adding phytase to low P diets linearly increased ADG (P < .001), rib shear force (P < .01), shear energy (P < .02), ash weight (P < .001) and ash percent (P < .001), Ca (P < .001) and P (P < .001) digestibility and digestible Ca (P < .001) and P (P <.001). Added P linearly increased ADG (P < .003), rib shear force (P < .003) shear energy (P < .001), ash weight (P < .001) and ash percent (P < .01), Ca (P < .02) and P (P < .001) digestibility and digestible Ca (P < .02) and P (P <.001). Based on phytase and P linear or nonlinear response equations for ADG, rib shear force, shear energy, and ash weight, P digestibility, and digestible P, the average equivalency of 500 U/kg of phytase was .78 g of P per kg of diet. In Exp. 2, dietary addition of phytase linearly increased rib ash % (P < .03), Ca (P < .001) and P (P < .001) digestibilities, and digested Ca (P < .001) and P (P < .001), but had no effect (P > .10) on ADG and rib shear force and ash weight. Added Ca linearly increased ADG (wk 3-4, P < .04), and rib shear force (P < .001), ash percentage (P < .001) and ash weight (P < .01), and digested Ca (P < .001), but P digestibility (P = .07) and digested P (P = .08) were numerically decreased. In Exp. 3, added phytase linearly increased ADG (wk 3-4, P < .002), feed efficiency (wk 3-4, P < .02), rib ash weight (P < .001), Ca total tract digestibility (P < .001), and Ca (P < .001) and P (P < .001) ileal digestibilities. Added Ca linearly increased ADG (wk 3-4, P < .02), feed efficiency (wk 3-4, P < .01), rib ash percentage (P < .001) and ash weight ( P < .001), shear force (P < .03) and energy (P < .008), and total tract (P < .001) and ileal (P < .001) digestible Ca. Based on phytase and Ca linear or nonlinear response equations for ADG in wk 3-4, measurements of rib mineralization, and digestible Ca, 500 U of microbial phytase was estimated to be equivalent to 1.08 g and .78 g of Ca in Exp. 2 and 3, respectively. In Exp. 4 and 5, dietary phytase addition linearly increased rib shear force (P < .004 and P < .02), shear energy (P < .001), dry bone weight (P < .001), ash weight (P < .001) and ash percent (P < .001). Calcium (P < .001) and P (P < .001) digestibilities were also improved in both experiments when phytase was added. Addition of citric acid in both experiments, reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved ADG (P < .05), feed efficiency (P < .04) and Ca digestibility (P < .05) in Exp. 4, but decreased Ca digestibility in Exp. 5 and had no effect on performance. In Exp. 5, the addition of 2.0% citric acid to the diet supplemented with 500 U/kg of phytase caused a decrease (P < .04) in the phytase activity recovered in the stomach digesta resulting in a phytase by citric acid interaction (P < .02). In summary, the addition of 500 U/kg microbial phytase to weanling pig diets, causes the release of approximately .78 g of P and .93 g of Ca, thus decreasing the need for supplemental P and Ca. The addition of citric acid to phytase supplemented diets does not appear to enhance the efficacy of microbial phytase based on the results of these studies."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-62597-112336"],"dc:identifier.uri":["http://hdl.handle.net/10919/36862"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Rib Mineralization","Pigs","Phytase","Phosphorus","Calcium","Citric Acid"],"dc:title":["Quantifying the Effects of Microbial Phytase and Diet Acidity on Ca and P Utilization by Weanling Pigs"],"dc:type":["Thesis"],"thesis:degree_discipline":["Animal and Poultry Sciences"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:41Z"}