Water metabolism in desert sheep. Effects of various degrees of water restriction on the distribution of body water in Marwari sheep

Abstract

The distribution of water in the different body compartments of eight sheep of the Marwari breed was determined after imposing the following treatments: watering ad lib., restriction to 75%, 50%, and 25% respectively of normal daily water requirements (each treatment of 5 days' duration, with a 7-day normal drinking regime between treatments), and complete deprivation of water for 3 days. The total body water, the total blood and plasma volumes, and the extracellular, intracellular, and interstitial fluid volumes of the animals began to decrease when the water intake was reduced below 75% of the normal daily requirement. A reduction to 25% normal was similar in its effect to complete deprivation, at which the plasma volume fell by 43% and the extracellular fluid volume by 33%. The findings clearly point to an unusual ability of these animals to maintain circulation even when faced with considerable haemoconcentration.

Physiological responses to water restriction in dry and lactating Awassi ewes

“…2). Similar results were obtained in many breeds with respect to water restriction in dry animals (MacFarlane et al, 1961;Purohit et al, 1972;Singh et al, 1982;Laden et al, 1987); except in water-restricted Yankasa sheep that showed no significant change (Aganga et al, 1989;Igbokwe, 1993). This increase could be attributed to a decrease in plasma volume due to water loss.…”

Physiological and chemical responses in water-deprived Awassi ewes treated with vitamin C

“…Some authors reported an increase in PCV in response to water stress (Laden et al, 1987;MacFarlane et al, 1961;Purohit et al, 1972;Singh et al, 1982), while others found no variation (Aganga et al, 1989;Igbokwe, 1993;Jaber et al, 2004). As for the observed decrease by the end of the experiment, subtropical breeds have the ability to maintain or even increase plasma and blood volumes (Ashour and Benlemlih, 2001) by drawing water from other body fluids mainly the rumen (Silanikove, 2000) and cellular sources (Macfarlane et al, 1961).…”

Effet d'une carence hydrique prolongée sur la croissance pondérale et sur le métabolisme hydrique chez un rongeur Gerbillidé (Meriones shawi shawi)

“…En effet, les mammifères non désertiques ne peuvent résister que quelques jours à une carence hydrique prolongée ; ainsi, le rat meurt au bout de deux semaines, alors que la mérione montre, dans les mêmes conditions, une baisse puis une stabilisation de poids (Rouffignac et Morel, 1965 (Schmidt-Nielsen, 1964 ;Ivanova travaux (Taneja, 1965 ;Purohit et al, 1972 ;More et Sahni, 1979 (Rouffignac et Morel, 1965 (Mac Millen et Lee, 1967 Blount, 1968). D'ailleurs il existe chez les rongeurs déserti-ques, d'une façon générale, une corrélation entre la surface médullaire rénale, l'épaisseur médullaire et la concentration urinaire (Browfield et Wunder, 1976 …”