Dou Z. auteur aut IRD Ramberg C. F. auteur aut IRD Chapuis Lardy Lydie auteur aut IRD Toth J. D. auteur aut IRD Wu Z. auteur aut IRD Chase L. E. auteur aut IRD Kohn R. A. auteur aut IRD Knowlton K. F. auteur aut IRD Ferguson J. D. auteur aut IRD text journalArticle eng text/pdf born digital access Managing P on dairy farms requires the assessment and monitoring of P status of the animals so that potential overfeeding may be minimized. Numerous published studies have demonstrated that for lactating dairy cows, increasing P concentrations in diets led to greater P excretion in feces. More recent work reported that inorganic P (P-i) in 0.1% HCl extracts of feces (fecal extract P-i, g/kg) closely reflects dietary P changes. This has led to the proposal that 0.1% HCl fecal extract P-i may serve as an indicator of the animal's P status (adequate or excessive) when compared with a benchmark value. Here, we present the results of an extensive evaluation of the proposed fecal P indicator test. With samples (n = 575) from >90 farms, fecal total P (TP, g/kg) and fecal extract P were positively correlated with dietary P (X, g/kg): TP = 1.92X - 0.17 (R-2 = 0.36); fecal extract P = 1.82X - 2.54 (R-2 = 0.46). Fecal extract P was responsive to dietary P changes, whereas the remaining P, calculated as TP minus fecal extract P, was not. A provisional benchmark value of fecal extract P representing near-adequate P status was set at 4.75 g/kg. Assessment of the farm data using the benchmark indicated that 316 out of 575 data points were associated with possible P overfeeding. Advantages of the fecal-based test over feed-based analysis to assess P status are discussed. The fecal extract P method is a simple and practical test that can be used as an assessment tool for helping dairy producers improve P management and reduce their environmental footprint. specialized fecal P test P overfeeding dairy farm assessment 080 021 93 2 830-839 2010 0022-0302 https://www.documentation.ird.fr/hor/fdi:010049268 10.3168/jds.2009-2153 0022-0302 [F B010049268] https://www.documentation.ird.fr/hor/fdi:010049268 https://www.documentation.ird.fr/intranet/publi/2010/02/010049268.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2010-03-10 2017-08-23 fdi:010049268 fre