Abstract

Water is a nutrient of extreme importance for animals and must be considered vital in any rearing phase. Small ruminants, especially sheep and goats, have social and economic importance due to their great ability in adapting to adverse environmental conditions and using water efficiently and are a major economic activity in the arid and semiarid regions of the world. Therefore, this paper aimed to review the effects of water stress on the adaptability of small ruminants in arid and semiarid regions. Many mechanisms work against water stress on small ruminants including behavioural, morphological, physiological, and biochemical mechanisms. Drinking behaviour in sheep and goats revealed interesting differences in the behavioural strategies between both species. Drinking behaviour was defined as follows: drinking frequency and drinking duration (time in minutes when the animal was actively engaged in the ingestion and swallowing of water). Morphological characteristics such as body shape and size help reduce heat loads and minimize water losses; it is noted that goat breeds of arid and semi-arid regions are relatively smaller than exotic breeds. Changes in rectal temperature (OF), pulse rate (no./min.) and respiration rate (no./min.) indicated the adaptability of the animals to increased thirst periods. Dehydration due to the thirst period provoked physiological mechanisms in the body in a manner that helped the animals to survive. Biochemical parameters like blood serum hormones, mineral profile, metabolites, and liver-kidney function were not affected by water restriction in goats so goats may survive at 50% restriction of water without affecting physiological indices and then their production. Moreover, Lower body weight gain and variation in physiological response and blood parameters in water-restricted animals reflect different adaptive strategies to counteract water restriction, as water restriction can increases stress in animals. The identification of breeds that show high adaptability to arid and semi-arid regions with an acceptable level of productivity is also important.

Keywords: Adaptability; Stress; Water