Water requirements and body water distribution in Awassi sheep and Aardi goats during winter and summer seasons

Water requirements, total body water (TBW) and water distribution were evaluated in Awassi sheep and Aardi goats of Saudi Arabia. Ten non-pregnant and non-lactating females from each species were individually housed in shaded pens during winter and summer seasons. Each experimental period lasted for 2 weeks; the first week was an adaptation period, followed by an evaluation period of 1 week. Feed and water intake together with body weight were recorded daily. Five animals from each group were used for determination of body water, extracellular fluid (ECF) and plasma volume (PV) using dilution techniques. Urea and sodium thiocyanate were used for the estimation of body water and ECF, respectively, and Evans blue for PV determination. Intracellular fluid (ICF) and blood volume (BV) were calculated. Feed intake was not affected by either season or species. During the winter season, Aardi goats had lower water intake in comparison with Awassi sheep, but water intake increased in all animals during summer. TBW increased during summer in all animals, but with higher values in the Aardi goats. During summer, ECF tended to increase in Aardi goats. PV, expressed as a proportion of body weight, was not affected by season, but it was maintained at higher levels in the Aardi goats irrespective of season. It could be concluded that Aardi goats used water more economically when the ambient temperature was lower but, during the summer when ambient temperatures were higher, they increased their water intake and BW content to a greater extent and stored more water in the ECF compartment compared to Awassi sheep.