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Fluid absorption from the rumen during rehydration in sheep.
1Department of Animal Physiology, Swedish University of Agricultural Sciences, Uppsala.
Experimental Physiology
|January 1, 1990
Summary
Sheep rapidly absorb water from the rumen after drinking, confirmed by tracking a fluid marker. This significant water absorption occurs even when animals eat or are rehydrated without food.
Area of Science:
- Ruminant physiology
- Animal hydration
- Gastrointestinal absorption
Background:
- Dehydration in sheep increases plasma osmolality, sodium, vasopressin, and renin.
- Understanding water movement across the rumen wall is crucial for animal hydration.
Purpose of the Study:
- To investigate the rate and extent of water absorption from the rumen following rehydration in sheep.
- To compare water absorption with and without food availability during rehydration.
Main Methods:
- Four fistulated sheep were dehydrated for 48 hours.
- A fluid marker (cobalt-EDTA) was introduced into the rumen; water intake was monitored.
- The reticulo-omasal orifice was occluded to prevent outflow during water absorption measurements.
- Plasma parameters (osmolality, Na+, vasopressin) were analyzed before and after rehydration.
Main Results:
- Sheep drank approximately 9 liters of water immediately upon rehydration.
- Rumen fluid marker concentration increased significantly post-drinking, indicating substantial water absorption (at least 11 L).
- Plasma osmolality and Na+ decreased in both feeding and non-feeding rehydration experiments, confirming water absorption.
Conclusions:
- Voluntary drinking in sheep leads to immediate and significant water absorption from the rumen.
- Rumen water absorption is a rapid process that contributes effectively to rehydration.
- The presence of food does not impede, but may dilute, the marker due to saliva production.