Moore J A, Pond K R, Poore M H, Goodwin T G
Department of Animal Science, North Carolina State University, Raleigh 27695-7621.
J Anim Sci. 1992 Nov;70(11):3528-40. doi: 10.2527/1992.70113528x.
Several models and markers are available for digesta kinetic studies. In this study, kinetic estimates derived from chromium-mordanted hay or pellets were compared to estimates derived from rare earth markers (Yb, Dy, or Er) applied individually to samples. Twelve yearling rams (52 kg) were given ad libitum access to either hay or a commercial pelleted diet in a crossover experiment. Digesta kinetic estimates were obtained both by nonlinear analysis with two age-independent rates (G1G1) or with gamma time dependency in the fast compartment (G2G1 to G4G1) and by linear regression of natural log transformed fecal marker concentrations (LN method of estimate). Model did not influence total tract (P > .21) or ruminal mean retention times (P > .87). Partitioning of total retention time was similar (P > .21) for the LN, G3G1, and G4G1 models, but the G1G1 and G2G1 models did not adequately fit these data. Nonlinear models overestimated, and LN underestimated, fecal DM output by 9% (SEM = 4.7) for the hay diet. All the nonlinear models provided fecal DM output estimates that were within 5% of actual fecal DM output, but the LN model underestimated it by 18% (SEM = 3.3) for the pelleted diet. Ruminal outflow rate was slower (P < .01) and both ruminal and total mean retention time estimates were longer (P < .01) for Cr than for the rare earths. Despite the marker chosen, relative diet effects were similar. The three rare earth markers gave identical results for digesta kinetic estimates, indicating that they are useful for simultaneous study of more than one ingredient or particle, but direct comparison of rare earth and Cr-mordant passage rates is not advisable.
有几种模型和标记物可用于食糜动力学研究。在本研究中，将源自铬媒染干草或颗粒饲料的动力学估计值与分别应用于样本的稀土标记物（镱、镝或铒）得出的估计值进行了比较。在一项交叉试验中，给12只一岁公羊（52千克）随意提供干草或商业颗粒饲料。通过具有两个与年龄无关的速率（G1G1）的非线性分析或快速隔室中具有伽马时间依赖性（G2G1至G4G1）的非线性分析以及通过对自然对数转换后的粪便标记物浓度进行线性回归（估计的LN方法）来获得食糜动力学估计值。模型对全消化道（P>.21）或瘤胃平均停留时间（P>.87）没有影响。对于LN、G3G1和G4G1模型，总停留时间的分配相似（P>.21），但G1G1和G2G1模型不能很好地拟合这些数据。对于干草日粮，非线性模型高估了粪便干物质产量，而LN模型低估了9%（标准误=4.7）。所有非线性模型提供的粪便干物质产量估计值与实际粪便干物质产量相差在5%以内，但对于颗粒饲料，LN模型低估了18%（标准误=3.3）。铬的瘤胃流出速率较慢（P<.01），铬的瘤胃和全消化道平均停留时间估计值均比稀土标记物的长（P<.01）。尽管选择了不同的标记物，但相对日粮效应相似。三种稀土标记物在食糜动力学估计方面给出了相同的结果，表明它们可用于同时研究多种成分或颗粒，但不建议直接比较稀土标记物和铬媒染物的通过速率。
