@article{leytem_kwanyuen_plumstead_maguire_brake_2008, title={Evaluation of phosphorus characterization in broiler ileal digesta, manure, and litter samples: P-31-NMR vs. HPLC}, volume={37}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2007.0134}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Leytem, A. B. and Kwanyuen, P. and Plumstead, P. W. and Maguire, R. O. and Brake, J.}, year={2008}, pages={494–500} }
 @article{plumstead_leytem_maguire_spears_kwanyuen_brake_2008, title={Interaction of calcium and phytate in broiler diets. 1. Effects on apparent prececal digestibility and retention of phosphorus}, volume={87}, ISSN={["1525-3171"]}, DOI={10.3382/ps.2007-00231}, abstractNote={Phytate P utilization from soybean meal (SBM) included in broiler diets has been shown to be poor and highly dependent on dietary Ca intake. However, the effect of Ca on P utilization and on the optimal ratio of Ca to nonphytate P (Ca:NPP) when diets contained varying levels of phytate has not been clearly shown and was the objective of this research. A factorial treatment structure was used with 4 dietary Ca levels from 0.47 to 1.16% and 3 levels of phytate P (0.28, 0.24, and 0.10%). Varying dietary phytate P levels were obtained by utilizing SBM produced from 3 varieties of soybeans with different phytate P concentrations. Ross 508 broiler chicks were fed 1 of 12 diets from 16 to 21 d of age. Excreta were collected from 16 to 17 d and from 19 to 20 d of age and ileal digesta was collected at 21 d of age. Apparent prececal P digestibility decreased when dietary Ca concentration increased and was higher when diets contained low-phytate SBM. The apparent digestibility of Ca and percentage of phytate P hydrolysis at the distal ileum were not reduced when dietary phytate P concentration increased. Including low-phytate SBM in diets reduced total P output in the excreta by 49% compared with conventional SBM. The optimum ratio of Ca:NPP that resulted in the highest P retention and lowest P excretion was 2.53:1, 2.40:1, and 2.34:1 for diets with 0.28, 0.24, and 0.10% phytate P. These data suggested that increased dietary Ca reduced the extent of phytate P hydrolysis and P digestibility and that the optimum Ca:NPP ratio at which P retention was maximized was reduced when diets contained less phytate P.}, number={3}, journal={POULTRY SCIENCE}, author={Plumstead, P. W. and Leytem, A. B. and Maguire, R. O. and Spears, J. W. and Kwanyuen, P. and Brake, J.}, year={2008}, month={Mar}, pages={449–458} }
 @article{leytem_plumstead_maguire_kwanyuen_burton_brake_2008, title={Interaction of calcium and phytate in broiler diets. 2. Effects on total and soluble phosphorus excretion}, volume={87}, ISSN={["0032-5791"]}, DOI={10.3382/ps.2007-00229}, abstractNote={Dietary Ca has been reported to influence the amount of phytate excreted from broilers and affect the solubility of P in excreta. To address the effects of dietary Ca and phytate on P excretion, 12 dietary treatments were fed to broilers from 16 to 21 d of age. Treatments consisted of 3 levels of phytate P (0.10, 0.24, and 0.28%) and 4 levels of Ca (0.47, 0.70, 0.93, and 1.16%) in a randomized complete block design. Feed phytate concentrations were varied by formulating diets with 3 different soybean meals (SBM): a low-phytate SBM, a commercial SBM, and a high phytate Prolina SBM having phytate P concentrations of 0.15 to 0.51%. Fresh excreta was collected from cages during 2 separate 24-h periods; collection I commenced after the start of dietary treatments (16 to 17 d) and collection II followed a 3-d adaptation period (19 to 20 d). Ileal samples were also collected at 21 d. Excreta samples were analyzed for total P, water soluble P (WSP), and phytate P, whereas ileal samples were analyzed for total P and phytate P. Results indicated that excreta total P could be reduced by up to 63% and WSP by up to 66% with dietary inclusion of low-phytate SBM. There was a significant effect of dietary Ca on both the excreta WSP and the ratio of WSP:total P. As dietary Ca increased, the excreta WSP and WSP:total P decreased, with the effects being more pronounced following a dietary adaptation period. There was a linear relationship between the slope of the response in WSP to dietary Ca and feed phytate content for excreta from collection II (r(2) = 0.99). There was also a negative correlation between excreta phytate concentration and excreta WSP during both excreta collections. The response in WSP to dietary manipulation was important from an environmental perspective because WSP in excreta has been related to potential for off-site P losses following land application.}, number={3}, journal={POULTRY SCIENCE}, author={Leytem, A. B. and Plumstead, P. W. and Maguire, R. O. and Kwanyuen, P. and Burton, J. W. and Brake, J.}, year={2008}, month={Mar}, pages={459–467} }
 @article{leytem_plumstead_maguire_kwanyuen_brake_2007, title={What aspect of dietary modification in broilers controls litter water-soluble phosphorus: Dietary phosphorus, phytase, or calcium?}, volume={36}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2006.0334}, abstractNote={ABSTRACT}, number={2}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Leytem, A. B. and Plumstead, P. W. and Maguire, R. O. and Kwanyuen, P. and Brake, J.}, year={2007}, pages={453–463} }
 @article{leytem_mikkelsen_2003, title={Separation of soil organic phosphorus compounds using reverse-phase ion-pair chromatography}, volume={34}, ISSN={["1532-2416"]}, DOI={10.1081/CSS-120020452}, abstractNote={Methods were developed for the extraction and separation of soil organic phosphorus compounds using reverse-phase ion-pair chromatography (RP-ICP). Nucleotides (ATP, ADP, and AMP) were separated using a mobile phase of 15 mM TBAHS, 15 mM KH2PO4, and 7% acetonitrile. Inositol hexakisphosphate was separated using a mobile phase composition of 0.05 M formic acid:methanol (49:51 v/v) and 1.5 mL/100 mL of TBAOH. Extraction procedures were developed for the nucleotides which would be compatible with the RP-ICP system developed for their separation.}, number={9-10}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Leytem, AB and Mikkelsen, RL}, year={2003}, pages={1393–1406} }
 @article{leytem_mikkelsen_gilliam_2002, title={Sorption of organic phosphorus compounds in Atlantic coastal plain soils}, volume={167}, DOI={10.1097/01.ss0000034854.98442.39}, number={10}, journal={Soil Science}, author={Leytem, A. B. and Mikkelsen, R. L. and Gilliam, J. W.}, year={2002}, pages={652–658} }