Phosphorus loads in waterways are a focus of environmental concern. Animal agriculture\'s contribution to this problem has been documented and efforts are focused on mitigating the issue. The effect of increasing amounts of mineral P supplementation on fecal P characteristics was studied in forage fed beef steers. Eight Hereford steers were fitted with total fecal collection bags and fed four diets with a low P grass hay and supplemented with increasing amounts of a mineral source of P, dicalcium phosphate. Dietary DM P concentrations were 0.10 (no P supplementation), 0.23, 0.34, and 0.45% P. Manure was sampled and dried, followed by analysis for total P and inorganic P (Pi). Blood was collected via jugular venipuncture following each collection period and plasma Pi was quantified. Total fecal P increased linearly with increasing dietary P concentration: 6.44, 10.6, 16.1, and 18.8 g/d (P < 0.0001). Fecal Pi increased linearly with increasing dietary P concentration: 1.58, 2.43, 2.74, and 3.84 g/d (P = 0.0119) Manure P solubility, however, did not increase with increasing dietary P concentration: 23.6, 22.3, 17.3, and 20.2% (P = 0.3646). Plasma Pi increased linearly with increasing dietary P (P = 0.0047). ADG and G:F were not affected by increasing dietary P content. Reducing or eliminating mineral P supplementation to forage fed beef animals is possible, if forage base proves to be adequate in P. Reducing dietary P reduces fecal P excretion and the pollution potential in ecologically sensitive areas like the Chesapeake Bay watershed. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/23230 |
| Date | 14 June 2013 |
| Creators | Riley, Elizabeth |
| Contributors | Animal and Poultry Sciences, Greiner, Scott P., Knowlton, Katharine F., McCann, Mark A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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