Developing a ruminal physiologically based model for the evaluation of dietary structural effectiveness in high-yielding dairys cows (Entwicklung eines ruminal-physiologischen Modells zur Bewertung der Strukturwirksamkeit von Rationen bei Hochleistungsmil

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Evaluation of dietary structural effectiveness is an important aspect in dairy cow nutrition, because this affects ruminal digestive processes, nutrient utilisation and animal health, and hence dairy productivity. This aspect gains importance especially in high-yielding dairy cow feeding, because of a high dry matter intake acquired and increased susceptibility to metabolic diseases. Although several evaluation systems have been developed, no unique and incontestable model could be accepted so far, because all systems are empirically established, based mainly on the response of chewing activity or milk fat maintenance to different individual feeds, while important physiological processes in the rumen are not accounted for. In the proposed current model, the physiological pathways of compartmental differences in reticulorumen concerning physiological-microbiological parameters along with mat stratification characteristics, digestive processes and particle kinetics will be dynamically, mechanistically integrated for defining a healthy rumen ecosystem, and to establish the basis for a unique, physiologically based model to predict the structural effectiveness and support fibre rationing in high-yielding dairy cows. For parameterization and calibration purposes of this model, original data recently obtained from extensive research studies will be included, while sensitivity analysis and validation will be performed using data from peer-reviewed, published international literature.