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On incorporating diffusion and viscosity concepts into compartmental models for analysing faecal marker excretion patterns in ruminants

Published online by Cambridge University Press:  09 March 2007

J. France ,
J. H. M. Thornley ,
R. C. Siddons  and
M. S. Dhanoa
J. France
Affiliation:
AFRC Institute of Grassland and Environmental Research, North Wyke Research Station, Okehampton, Devon EX20 2SB
J. H. M. Thornley
Affiliation:
Intitute of Terrestrial Ecology, Edinburgh Research Station, Bush Estate, Penicuik, Midlothian EH26 OQB
R. C. Siddons
Affiliation:
formerly AFRC Institute of Grassland and Environmental Research, Hurley, Maidenhead, Berkshire SL6 5LR
M. S. Dhanoa
Affiliation:
AFRC Institute of Grassland and Environmental Research, Plus Gogerddan, Aberystwyth, Dyfed SY23 3EB
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Abstract

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Deterministic mathematical equations are derived to describe the pattern of marker excretion in the faeces of ruminants under steady-state conditions when diffusion and viscosity concepts are introduced into a simple two-compartment scheme of the gastrointestinal tract. The basic scheme comprises a pure-mixing pool obeying first-order kinetics and a second compartment exhibiting streamline flow. Introduction of a velocity gradient, longitudinal diffusion or both into the second compartment, even with various simplifying assumptions, yields analytically insoluble equations. The impact of these mechanisms is to be investigated numerically rather than analytically in future work.

Keywords

DiffusionViscosityCompartmental modelsFaecal marker excretion patternsRuminants
Type
Modelling of Intestinal Flows
Information
British Journal of Nutrition , Volume 70 , Issue 1 , July 1993 , pp. 369 - 378
Copyright
Copyright © The Nutrition Society 1993

References

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