Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Journal of Dairy Science 830-839 fecal P test P overfeeding dairy farm assessment 2010 fdi:010049268 ENG Journal of Dairy Science 0022-0302 ISI:000274102500042 2 10.3168/jds.2009-2153 https://www.documentation.ird.fr/hor/fdi:010049268 https://www.documentation.ird.fr/intranet/publi/2010/02/010049268.pdf 93 Horizon (IRD) 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. 080 ; 021 UR210