| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Center for Animal Health and Productivity, School of Veterinary Medicine, University of Pennsylvania Kennett Square 19348
Corresponding author: Z. Dou; e-mail: douzheng{at}vet.upenn.edu.
Recent data from phosphorus (P) feeding trials have demonstrated that P concentration in dairy feces is directly affected by P levels in diets and that farm P surpluses as well as potential environmental losses can be reduced through dietary manipulation. The current study was conducted to examine the variability of fecal P under farm conditions and to elucidate factors affecting the concentration and solubility of fecal P. Feed and fecal samples from >30 commercial dairies in the Northeast and Mid-Atlantic regions were analyzed. Dietary P concentrations ranged from 3.45 to 5.78 g/kg of feed DM (DM), and P determined in acid digests (TP) of feces from 5.84 to 12.84 g/kg of fecal DM. On average, 50% of fecal TP was water soluble; of the latter, 83% was inorganic (Pi). Across-farm variability (n = 33) had CV averaging 18.9% for fecal TP and >20% for Pi and total P (Pt) in water extracts. Within-farm variability based on multiple samples per herd had the same magnitude as across-farm and was independent of sample numbers from individual farms (n = 7 to 30). Of all fecal parameters determined, pH and DM had the lowest variability (CV <10%), water-soluble Pi, Pt, and Ca the highest (CV of 20 to 30%), and total P, Ca, and Mg determined by acid digests were intermediate (CV 10 to 20%). Water-soluble Pi concentrations determined in dried-ground fecal samples were lower than in wet samples. The drying-grinding process changes Pi solubility and the change is not linear. This study confirms that dietary P concentration is the dominating factor affecting fecal P excretion; however, Ca concentration, DIM, and fecal pH also made small, but statistically significant contributions, although some of the mechanisms remain to be thoroughly investigated.
Key Words: dairy farm • phosphorus • dietary management
Abbreviation key: TP = phosphorus determined in acid digests, Pi = inorganic phosphorus, Po = organic phosphorus, Pt = total phosphorus (Pi and Po) in extracts.
This article has been cited by other articles:
|
|
 |
|
  R. W. McDowell, Z. Dou, J. D. Toth, B. J. Cade-Menun, P. J. A. Kleinman, K. Soder, and L. Saporito A Comparison of Phosphorus Speciation and Potential Bioavailability in Feed and Feces of Different Dairy Herds Using 31P Nuclear Magnetic Resonance Spectroscopy J. Environ. Qual., May 1, 2008; 37(3): 741 - 752. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Gungor, A. Jurgensen, and K. G. Karthikeyan Determination of Phosphorus Speciation in Dairy Manure using XRD and XANES Spectroscopy J. Environ. Qual., October 24, 2007; 36(6): 1856 - 1863. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. A. Vadas, W. J. Gburek, A. N. Sharpley, P. J. A. Kleinman, P. A. Moore Jr., M. L. Cabrera, and R. D. Harmel A Model for Phosphorus Transformation and Runoff Loss for Surface-Applied Manures J. Environ. Qual., January 9, 2007; 36(1): 324 - 332. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Shober, D. L. Hesterberg, J. T. Sims, and S. Gardner Characterization of Phosphorus Species in Biosolids and Manures Using XANES Spectroscopy J. Environ. Qual., October 27, 2006; 35(6): 1983 - 1993. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. S. Dias, E. Kebreab, D. M. S. S. Vitti, A. P. Roque, I. C. S. Bueno, and J. France A revised model for studying phosphorus and calcium kinetics in growing sheep J Anim Sci, October 1, 2006; 84(10): 2787 - 2794. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. N. Hristov, W. Hazen, and J. W. Ellsworth Efficiency of use of imported nitrogen, phosphorus, and potassium and potential for reducing phosphorus imports on idaho dairy farms. J Dairy Sci, September 1, 2006; 89(9): 3702 - 3712. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. A. Vadas and P. J. A. Kleinman Effect of Methodology in Estimating and Interpreting Water-Extractable Phosphorus in Animal Manures J. Environ. Qual., May 31, 2006; 35(4): 1151 - 1159. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. O. Maguire, Z. Dou, J. T. Sims, J. Brake, and B. C. Joern Dietary Strategies for Reduced Phosphorus Excretion and Improved Water Quality J. Environ. Qual., November 7, 2005; 34(6): 2093 - 2103. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. S. Toor, B. J. Cade-Menun, and J. T. Sims Establishing a Linkage between Phosphorus Forms in Dairy Diets, Feces, and Manures J. Environ. Qual., July 5, 2005; 34(4): 1380 - 1391. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
