Section of Animal Production Systems, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square 19348.
J Dairy Sci. 2010 Feb;93(2):830-9. doi: 10.3168/jds.2009-2153.
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 (R2=0.36); fecal extract P=1.82X - 2.54 (R2=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 4.75g/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.
在奶牛场管理磷需要评估和监测动物的磷状况，以尽量减少潜在的过度喂养。许多已发表的研究表明，对于泌乳奶牛，增加日粮中的磷浓度会导致粪便中磷排泄量增加。最近的研究报告称，粪便（粪便提取磷，g/kg）中 0.1%盐酸提取物中的无机磷（P(i)）可以很好地反映日粮中磷的变化。这导致提出 0.1%盐酸粪便提取 P(i)可作为动物磷状况（充足或过度）的指标，与基准值进行比较。在这里，我们介绍了对拟议的粪便磷指示剂试验的广泛评估结果。在来自>90 个农场的 575 个样本中，粪便总磷（TP，g/kg）和粪便提取磷与日粮磷（X，g/kg）呈正相关：TP=1.92X-0.17（R2=0.36）；粪便提取磷=1.82X-2.54（R2=0.46）。粪便提取磷对日粮磷变化敏感，而其余的 P（计算为 TP 减去粪便提取磷）则不然。设定粪便提取磷的暂定基准值为 4.75g/kg，代表接近充足的磷状态。使用基准值评估农场数据表明，575 个数据点中有 316 个可能与磷过度喂养有关。讨论了基于粪便的测试相对于基于饲料的分析来评估磷状况的优势。粪便提取磷方法是一种简单实用的测试方法，可作为评估工具，帮助奶牛生产者改善磷管理并减少其环境足迹。
