Differences between sheep excreting sodium predominantly in their urine or in their faeces: the effect of changes in sodium intake.
Sheep receiving a total of about 31 mmol day-1 (0.5 mmol kg-1) of sodium were classified according to the predominant route of sodium excretion; urinary (U) or faecal (F). U sheep had a greater water turnover than F sheep; their intake was 41% higher and they produced 133% more urine but there was little difference in faecal water loss. Most faecal sodium was readily exchangeable with water in both groups. When sodium intake was reduced by 80% (to 6 mmol day-1; 0.1 mmol kg-1), the reduction in total sodium excretion was equally effective in F sheep and U sheep after 48 h and after 2 weeks the overall losses of sodium were smaller in F sheep. On sodium intakes close to requirement (0.1 mmol kg-1 or less) the majority of the sheep excreted most of their sodium in faeces and did so on intakes up to 0.5 mmol kg-1 day-1. Excess dietary sodium is mainly excreted renally. When sodium intake is increased abruptly (by 20 mmol day-1, 0.3 mmol kg-1), total sodium excretion only increases gradually but after about 3 days it 'overshoots' as in humans.
Michell
A R
AR
Department of Large Animal Medicine and Surgery, Royal Veterinary College (University of London), Hatfield, Herts.
Moss
P
P
D000818:Animals; D001834:Body Water / Q000378:metabolism; D004039:Diet, Sodium-Restricted; D004231:Diuresis / Q000187:drug effects; D005243:Feces / Q000737:chemistry*; D005260:Female; D009994:Osmolar Concentration; D012756:Sheep; D012964:Sodium / Q000032:analysis / Q000494:pharmacology / Q000652:urine*; D014867:Water / Q000032:analysis
D014867:Water; D012964:Sodium