This study was conducted at Maryout Experiment Station near Alexandria, 32° latitude, affiliated to the Desert Research Center in Cairo. In this study, the effect of heat stress resulting from the combined effects of water deprivation, the housing environment and season of the year on the changes of rectal (RT) and skin temperature (ST) and their amplitude (differences between morning and afternoon values), as well as gradients between core and surface temperatures and the ambient temperature were investigated in eight non-pregnant and non lactating adult 4-5 years old Barki ewes fed at the maintenance energy level. Half the animals were watered daily whereas the other half was watered intermittently, once every 3 days. Moreover, half the animals were kept outdoors and not sheltered whereas the other half was housed indoors. The experimental treatments were repeated three times between April and August to represent spring, early summer and late summer seasons. Ambient temperature (Ta), relative humidity (RH%) and animal data, rectal (RT) and skin (ST) temperatures were recorded twice daily at 7:00 AM and 2:00 PM for three consecutive days representing a complete water deprivation cycle. It was noticeable that the housing environment was a significant source of variation affecting RT, ST and their amplitude, as well as core, skin, and ambient temperature gradients. RT and ST were always lower outdoors than indoors in the morning. Conversely, in the afternoon they were higher outdoors than indoors. Therefore, outdoor RT and ST differences (PM-AM) and gradients were greater than those indoors. On the other hand, time of the year (spring, early summer, and late summer) was a statistically significant source of variation affecting ST and rectal-skin gradient in the afternoon and rectal-air and skin-air in the morning and in the afternoon. The effect of water deprivation was not significant on RT, ST, their amplitude or gradients. Evident was the capacity of sheep to maintain constant, the overall rectal-air temperature gradient through varying rectal-skin and skin-air gradients, and invariably in opposite direction. This was aided by the fact that Ta were constantly lower than the RT and ST. Hence, the temperature of the skin and its regulation determines to a large extent the core temperature of sheep. In further studies gradual and long term adaptation experiments, longer cycles of water deprivation and measurement of body fluid changes and stress telated hormones would be needed.

The study was carried out at Maryout Research Station, 35 km to Southwest of Alexandria that belongs to the Desert Research Center (DRC), Egypt. The study was performed to evaluate the thermoregulatory ability of one-humped she camel (Camelus dromedarius) during summer and winter seasons. Five adult healthy shecamels aged 6-8 years with initial body weight recorded 522.00±3.52 and 613.00±6.63 kg for summer and winter seasons, respectively, were used. The animals were kept in outdoor pen (un-shaded). Rectal (RT), skin surface (SST), surface coat (SCT) and mid-coat (MCT) temperatures were measured 3 times daily (6:00 am; 12:00 pm and 6:00 pm) during the ten middle days of each month during both summer (from June till August) and winter (from December till February). Ambient temperature and relative humidity were recorded at 06:00, 12:00 and 18:00 hr during summer and winter seasons. Regarding the effect of season on RT, the results indicated that there were significant differences (P<0.01) between seasons. Average RT was 38.6 and 37.45 ºC during summer and winter seasons, respectively. In general, seasonal and diurnal variations in rectal temperature followed closely observed changes in the temperature-humidity index (THI). Skin surface temperature (SST) varied between the selected sites over the animal's body and between seasons. The changes in SST at the selected sites were higher (P<0.01) under cold climatic conditions (winter) than warm climatic conditions (summer). These results indicated that SST was dependent on climatic conditions. The results revealed that SST recorded highly (P<0.01) significant differences between hump (represent site exposed to sun) and abdomen (represent site not exposed to sun). The hump site was the warmest during summer (35.5 and 33.27 ºC) and winter (16.23 and 20.17 ºC) for SCT and MCT, respectively, whereas AB site recorded the lowest readings during summer (30.30 and 28.57 ºC) and winter (10.70 and 13.07 ºC) for SCT and MCT, respectively. The mid-coat temperature is less than surface-coat temperature in summer in order to decrease the transfer of heat from air to the skin. Meanwhile, the mid-coat temperature is more than surface-coat temperature in winter to minimize or prevent the dissipation of heat from the skin to the environment and preserve skin temperature as much as possible. The camels' coats, which are hairy rather than wooly in nature, create a favorable microclimatic buffer zone that separate the body surface from the surrounding harsh climatic conditions.

The present study was intended to investigate the effects of watering regimen, protein intake, housing environment and season on the potential losses of urea, sodium and potassium in the sweat of Barki sheep. Sweating rate, Na + , K + and urea concentration in sweat and serum, and sweat Na + , K + and urea output were determined in eight non-pregnant non-lactating Barki ewes fed at the maintenance energy level. Half of the animals were watered daily, whereas the other half was intermittently watered once every three days. There were two levels of protein intake, however, 100% and 50% of their estimated maintenance requirements. Moreover, half of the animals were kept outdoors and not sheltered whereas the other half was housed indoors. The experimental treatments were repeated three times between April and August to represent spring, early summer, and late summer seasons. The sweating rate in daily watered sheep was about 108 g/m 2 /h. The outdoor sheep had significantly higher sweat rates than those kept indoors. Also, the sweating rate of sheep in early and late summer was significantly higher than those in spring. Water deprivation and the level of protein intake did not significantly affect sweat rate. The urea excreted in sweat followed changes in sweat rate. Urea output increased in animals kept outdoors as compared to indoors and in summer as compared to spring. The sweat:serum urea concentration ratio was always less than one. The ratio ranged from 0.5 to 0.1 which possibly indicates passive diffusion of urea into the sweat. Sweat:serum concentration ratio ranged from 1.00 to 1.87 for sodium and from 149.7 to 224.5 for potassium for the different experimental treatments. Consequently, the sweat K + output was much greater than that of Na + even though its serum concentration was much less than Na +. The increase in K/Na ratio may suggest the presence of a Na + :K + exchange mechanism in the duct of the sweat gland similar to that in the distal tubule of the kidney. The present results gave evidence that losses of potassium, sodium and to some extent urea in sweat could be quantitatively significant affecting the nutritional and physiologic state of the desert animal and in particular the acid-base balance of blood and other body fluids. Quantitative assessment of such losses under different conditions of environmental stress would be essential in devising sound management systems.

This study was conducted at Maryout Experimental Station near Alexandria, 32° latitude affiliated to the Desert Research Center in Cairo. In this study, the effect of heat stress resulting from the combined effect of water deprivation, the housing environment and season of the year on the changes of rectal (RT) and skin temperature (ST) and their amplitude (differences between morning and afternoon values), as well as gradients between core and surface temperatures and the ambient temperature were investigated in eight non-pregnant and non lactating female dromedary camels fed at the maintenance level. Half the animals were watered daily whereas the other half was intermittently watered, once every 7 days. Moreover, half the animals were kept outdoors and not sheltered whereas the other half was housed indoors. The experimental treatments were repeated three times between April and August to represent spring, early summer and late summer seasons. Climatic (ambient temperature (Ta), relative humidity (RH%) and temperature humidity index (THI) and animal data (RT and ST) were recorded twice daily at 7:00 am and 2:00 pm for seven consecutive days representing a complete water deprivation cycle.It was evident that the housing environment in the morning was a significant source of variation affecting both RT and ST and their amplitude, as well as core, skin and ambient temperature gradients. Water deprivation also represented another significant source of variation that affected (RT), both in the morning and in the afternoon. However, (ST) was significantly affected by season only in the morning. All the above parameters were significantly affected by days of the water deprivation cycle.It was noticeable that the RT of the water deprived camels kept outdoors was consistently lower than their control mates. Largest average RT amplitude was observed in the water deprived camels housed outdoors which was 4 folds of their water deprived mates housed indoors. On the other hand, ST behaved differently in such a way that in the water deprived camels it was frequently higher than in the daily watered controls. Evident was the capacity of camels to maintain constant, the overall rectal-air temperature gradient through varying rectal-skin and skin-air gradients, and invariably in opposite direction. This was aided by the fact that (Ta) were constantly lower than the (RT) and (ST). Hence, the temperature of the skin and its regulation determines to a large extent the core temperature of camels.

Blood and tissue lipids of camels were studied in summer and winter, where fat mobilization and deposition, respectively, may prevail parallel to the changing food availability and the nutritional state. When animals were better nourished in winter, serum concentrations of total lipids, triglycerides and total cholesterol increased. Extracted fat content in adipose tissue was also greater in winter than in summer. Adipose fatty acids were less saturated and average chain length was shorter in winter than in summer. Further experimentation dealing with possible metabolic adaptations in camels in comparison to ruminants is warranted.