Schofield P, Pitt R E, Pell A N
Department of Animal Science, Cornell University, Ithaca, NY.
J Anim Sci. 1994 Nov;72(11):2980-91. doi: 10.2527/1994.72112980x.
In vitro gas production, measured by computer-interfaced pressure sensors, was used to follow the digestion of a crystalline processed cellulose, a bacterial cellulose, and mixtures of these substrates by mixed ruminal bacteria. A first-order, substrate limited model (simple exponential with lag) and two bacterial growth models (logistic, Gompertz) were tested to fit these data. No single pool model gave an optimal fit to all substrates, but dual pool versions of both the logistic and Gompertz models fitted the data extremely well. Derivations of these models in the context of gas production are presented. The dual pool version of the exponential model commonly used to analyze fiber digestion was not able to reproduce the slope variations seen with mixed substrates. A modified dual pool logistic equation, with a single lag value, was selected to model the in vitro digestion of these substrates. The model was able to predict adequately both the input composition and the kinetic parameters for a defined mixture and gave a good fit (r2 > .995) to data from all the single and mixed substrates tested. This model may be useful for interpreting gas accumulation from natural feedstuffs.
通过计算机接口压力传感器测量的体外产气情况，被用于跟踪混合瘤胃细菌对结晶加工纤维素、细菌纤维素以及这些底物混合物的消化过程。测试了一阶底物受限模型（带滞后的简单指数模型）和两种细菌生长模型（逻辑斯蒂模型、冈珀茨模型）以拟合这些数据。没有单一池模型能对所有底物实现最优拟合，但逻辑斯蒂模型和冈珀茨模型的双池版本对数据的拟合效果非常好。文中给出了这些模型在产气背景下的推导。常用于分析纤维消化的指数模型的双池版本无法重现混合底物时出现的斜率变化。选择了一个具有单个滞后值的修正双池逻辑斯蒂方程来模拟这些底物的体外消化。该模型能够充分预测特定混合物的输入组成和动力学参数，并且对所有测试的单一和混合底物的数据拟合良好（r2 >.995）。该模型可能有助于解释天然饲料的气体积累情况。
