Animal Nutrition Group, Wageningen University & Research, WD Wageningen, The Netherlands.
J Anim Sci. 2021 Feb 1;99(2). doi: 10.1093/jas/skab020.
Growing importance of upcycling agricultural by-products, food waste, and food processing by-products through livestock production strongly increased the variation in the nutritional quality of feed ingredients. Traditionally, feed ingredients are evaluated based on their measured extent of digestion. Awareness increases that in addition to the extent, the kinetics of digestion affects the metabolic fate of nutrients after absorption. Together with a growing body of evidence of complex interactions occurring within the lumen of the digestive tract, this urges the need of developing new approaches for feed evaluation. In a recently developed approach, we propose combining in vitro and in silico methods for feed ingredient evaluation. First steps in the development of such a systems were made by (1) evaluating in vitro the digestion potential of feed ingredients, regarding this as true ingredient properties and (2) predicting in silico the digestive processes like digesta transit, nutrient hydrolysis and absorption using dynamic, mechanistic modeling. This approach allows to evaluate to what extent the digestion potential of each ingredient is exploited in the digestive tract. Future efforts should focus on modeling digesta physicochemical properties and transit, applying in vitro digestion kinetic data of feed ingredients in mechanistic models, and generating reliable in vivo data on nutrient absorption kinetics across feed ingredients. The dynamic modeling approach is illustrated by a description of a modeling exercise that can be used for teaching purposes in digestive physiology or animal nutrition courses. A complete set of equations is provided as an on-line supplement, and can be built in modeling software that is freely available. Alternatively, the model can be constructed using any modeling software that enables the use of numerical integration methods.
通过畜牧业生产，对农业副产物、食品废弃物和食品加工副产物的再利用变得越来越重要，这极大地增加了饲料成分的营养价值变化。传统上，饲料成分是根据其可测量的消化程度来评估的。人们越来越意识到，除了消化程度外，消化动力学还会影响吸收后营养素的代谢命运。再加上在消化道腔内发生的复杂相互作用的大量证据，这就迫切需要开发新的饲料评估方法。在最近开发的一种方法中，我们建议将体外和计算机模拟方法结合起来用于饲料成分评估。为此，我们首先（1）评估饲料成分的体外消化潜力，将其视为真正的成分特性，以及（2）使用动态、机械模型来预测消化过程，如食糜转运、营养水解和吸收。这种方法可以评估每个成分的消化潜力在消化道中被利用的程度。未来的工作应集中于模拟食糜的物理化学特性和转运，将饲料成分的体外消化动力学数据应用于机械模型，并生成关于各种饲料成分的营养吸收动力学的可靠体内数据。动态建模方法通过描述一个建模练习来说明，该练习可用于消化生理或动物营养课程的教学目的。提供了一套完整的方程作为在线补充，并可在免费提供的建模软件中构建。或者，可以使用允许使用数值积分方法的任何建模软件来构建模型。
