Abstract
The objective of this study was to investigate the seasonal variation in physiological performance of camels and sheep raised under semi-arid environment of Saudi Arabia. Six sexually mature animals of each of camels and sheep were used in this study. They were housed separately and individually in open partly shaded yards. Ambient temperature averaged 39.83+/-2.13 and 19.79+/-3.78 degrees C and relative humidity averaged 6.98+/-1.18 and 26.22+/-0.65% during Summer and Winter seasons, respectively. The calculated average Temperature Humidity Index (THI) was 4173+/-1.38 and 18.38+/-0.21 during Summer and Winter seasons, respectively. The shift in season from Winter to Summer had significantly (p<0.05) elevated rectal temperature in both camels and sheep. However, the increase in rectal temperature during Summer season was two folds higher in sheep compared to camels. Likewise, skin. temperature was significantly (p<0.05) increased in both species during Summer season. However, the increase in skin temperature during Summer season was almost four folds higher in sheep compared to camels. Hematological parameters were elevated in both species with the shift of season from Winter to Summer with the exception of Red Blood Cells count (RBC), Packed Cell Volume (PCV) and Mean Corpuscular Volume (MCV) which were decreased in sheep. However, biochemical parameters were more affected by seasonal shift from Winter to Summer in sheep than those in camels. The seasonal variation in body temperature and blood composition was evident in both species with higher effect in sheep than in camels in terms of biochemical parameters and body temperature which indicates better adaptation of camels to hot Summer conditions of the semi-arid environment.