An investigation into the effect of sodium content in plantain (Plantago lanceolata) on urine production in sheep

Abstract

The effect of the high sodium content of plantain on urine production in sheep was investigated. Two groups of sheep (n=10) were fed either perennial ryegrass or plantain for 3 days. Allocated feeds were balanced for water and sodium. Water intake, faecal water, and urine volume were measured daily to determine water balance. Plasma and urine samples were measured twice daily for sodium and osmolality. Creatinine, urea and free water clearance were calculated twice daily for each animal. After 10 days the trial was repeated for 2 days using two different groups of sheep. Plantain sheep had a higher urine volume (increase of about 50%) and a lower daily water balance (by about 600 ml) than the ryegrass sheep. Sodium excretion (g/day) in urine was higher in the plantain group. The day with the largest difference in water balance and smallest difference in sodium excretion was Day 3 of Week 1. There were positive relationships shown between the extra sodium ingested by the ryegrass group and the urine volume and sodium excreted in urine. These results confirm plantain causes an increase in dilute urine, without effecting total osmols excreted. They suggest that the higher sodium content in plantain accounts for some of the increase in urine production of the sheep, but the small differences in sodium excreted and large differences in urine volumes suggest sodium is not the only factor causing the diuresis.