Effect of water deprivation and season on feed intake, body weight and thermoregulation in Awassi and Najdi sheep breeds in Saudi Arabia

Studies were conducted to compare responses to water deprivation in two local sheep breeds of Saudi Arabia, Awassi and Najdi, during different seasons. During water deprivation, body weight was significantly reduced (l) < 0.01) by 11% during winter in both breeds, while it decreased 13.3% and 15.3% in Awassi and Najdi sheep in spring, and the corresponding values with reduction for summer were 18% and 21.5%. The decline in feed intake as a result of dehydration was highest in summer (96.5%) followed by spring (75%) and winter (62%) in both breeds. Water deprivation reduced (p < 0.01) respiration rate during winter and spring, and increased rectal temperature during spring and Summer. Sweating rate was reduced in water-deprived sheep during summer and Awassi breed maintained lower sweating activity. Both breeds were able to consume a volume of water within 15 min following rehydration, which was amounting to 18.9%, 13.8% and 9.8% of their dehydrated body weights in summer, spring and winter, respectively. The lower rate of body weight loss and the maintenance of lower sweating activity during dehydration of Awassi indicated better ability of water conservation compared to Najdi breed. It was concluded that Awassi sheep possess better capability of withstanding water deprivation than Najdi sheep particularly when it was coupled with higher environmental temperature. (C) 2004 Elsevier Ltd. All rights reserved.