title: [Simulation of nutrient dynamics in the rumen of sheep and cattle considering the feed composition, level of feed intake and feeding frequency. 1. Model description].
abstract: The aim of this work was to develop a dynamic, mechanistic computer-model, which can be used to simulate digestion, outflow and pools of different nutrients in the rumen of sheep and cattle and which reacts on changes of the feed composition, on the level and the frequency of feeding. The model consists of 35 flux- and 17 differential equations and works under cyclic steady-state conditions. The following mechanism are integrated into the model: The three substrates protein, neutral detergent fibre (NDF) and non-fibre-carbohydrates are degraded by three specific groups of microbes. A fourth group degrades NDF and non-fibre-carbohydrates following the principle of competitive inhibition. The fermentation in the rumen serves for supply of energy for growth and for the maintenance of microbes. The rates of degradation are calculated from the turnover-time of the specific substrate and the amount of microbes. Recycling of N occurs through recycling of the microbial protein and the ruminohepatic pathway. If concentration of ammonia in rumen fluid decreases below 50 mg/l then the growth of microbes declines.
authors.affiliation: Institut für Tierernährung der Universität Hohenheim, Stuttgart, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Grathwol
authors.forename: J R
authors.initials: JR
authors.lastname: Reichl
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D004063:Digestion; D005247:Feeding Behavior; D006128:Growth; D008433:Mathematics; D008954:Models, Biological; D012417:Rumen / Q000382:microbiology / Q000502:physiology*; D012756:Sheep; D013997:Time Factors
vernacular_title: Simulation der nährstoffdynamik im pansen von schaf und rind unter berücksichtigung der futterzusammensetzung, des fütterungsniveaus und der fütterungsfrequenz. 1. Mitteilung--Modellbeschreibung.