Drying dynamics of pellet feces.
Benjamin Magondu1, Alexander B Lee2, Andrew Schulz3
1Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Soft Matter
|January 6, 2023
Summary
Fecal pellet shape in mammals is determined by intestinal drying processes. A critical water content threshold of 0.65 distinguishes cylindrical from pellet feces, with length correlating to water absorption flux.
Area of Science:
- Comparative physiology
- Animal science
- Biophysics
Background:
- Pellet feces are common in many mammals, including those vital for research and agriculture.
- Understanding fecal morphology can offer insights into animal health and dietary habits.
Purpose of the Study:
- To investigate the hypothesis that pellet feces form through drying within the intestine.
- To explore the relationship between fecal water content, intestinal absorption, and fecal shape across mammalian species.
Main Methods:
- Analysis of fecal shape across 22 mammalian species, correlating it with water content.
- Development of a mathematical model to simulate fecal water absorption and pellet formation.
- Experimental validation using a corn starch drying model to mimic intestinal processes.
Main Results:
- A transition from cylindrical to pellet feces occurs when fecal water content falls below 0.65.
- Pellet feces length (L) scales with water absorption flux (J) as L ~ J^-2.08, according to the mathematical model.
- The experimental drying model showed pellet length scaling with water flux as J^-0.46.
Conclusions:
- Intestinal drying is a key factor in pellet feces formation.
- Fecal length can potentially serve as a biomarker for intestinal health in veterinary and medical contexts.
- While inspired by geological jointing, the scaling exponents suggest different formation mechanisms for pellet feces and columnar jointings.
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