Shorn and unshorn Awassi sheep I. Body temperature

Abstract

1. The rectal temperatures of shorn and unshorn Awassi sheep were measured at various hours of the day and during various seasons of the year in two different locations in Israel.2. An increase in body temperature accompanied an increase in environmental temperature. A steeper temperature increase was noted in shorn sheep kept in the shade. When ambient temperatures were below 30° C. the body temperature of shorn sheep was lower than that of the unshorn sheep by an average of 0·16° C.3. When ambient temperatures were above 30° C. the body temperature of shorn sheep was equal to or higher than that of unshorn ones.4. Upon exposure to direct sunlight, the body temperature of shorn sheep exceeded that of unshorn animals. However, when the animals were transferred to the shade, or after sunset, the shorn sheep cooled at a faster rate. Their body temperature fell below that of the unshorn sheep during the cool hours of the day.5. Wind velocity, both in the shade and in the sun, had a greater effect on shorn than on unshorn sheep.6. A rise in the relative humidity of ambient temperatures above 25° C. caused body temperature to rise, particularly in unshorn animals. The body temperature of shorn sheep exceeded that of unshorn ones when the animals were maintained in a hot and dry environment.7. While the body of the shorn sheep was entirely affected by the macroclimate, the unshorn sheep were greatly influenced by the microclimate existing in the fleece. Fleece temperatures always lagged behind and were rarely equal to environmental temperatures. Since it was postulated that heat tolerance of certain animals was related to their ability to exploit cool hours of the day, it is suggested that in certain ‘tolerance tests’ records should be taken not only during exposure to heat but also during cool hours of the day.

The deep body temperature of an unrestrained Welsh Mountain sheep recorded by a radiotelemetric technique during a 12‐month period

“…Previous long-term studies of the deep body temperature patterns of sheep have varied widely in technique, experimental regime and location, and the breed studied, but the results agree well with the essential points reported here. Eyal (1963), in his studies of the nychthemeral variations in rectal temperature of shorn and unshorn Awassi sheep during summer and winter, and in sunshine and shade, in Israel, found a monophasic nychthemeral variation of less than 10 C in all these circumstances, with the lowest temperature in the early morning and the highest in the evening. Minett & Sen (1945), Miller & Monge (1946) and Veeraraghavan & Mendel (1963) have also reported similar monophasic nychthemeral variations in the rectal temperature of different breeds of sheep.…”

“…Eyal (1963), however, found remarkably little difference in the thermoregulatory behaviour of shorn and unshorn sheep. In the study reported here, the Welsh Mountain sheep did not always use the shelter when the weather was bad.…”

“…Existing knowledge of the nychthemeral (24 hourly) and seasonal variations in body temperature derives from discontinuous measurements of rectal temperature under field or laboratory conditions which have required varying degrees of restraint and handling. In consequence, despite innumerable laboratory studies of the physiological processes upon which mammalian homoeothermy depends, there is little reliable information on the degrees of thermostability which different species of mammals actually achieve under natural conditions.In the context of previous observations on the thermoregulatory physiology of sheep (Bligh, 1959(Bligh, , 1961(Bligh, , 1963 (Minett & Sen, 1945;Symington, 1960;Eyal, 1963) have been subject to the experimental limitations mentioned above.In principle, two techniques can be used to avoid the frequent attentions of the observer. An indwelling thermosensitive element can be coupled either to a miniature recorder attached to the animal, or to a portable radio transmitter.…”

“…In the context of previous observations on the thermoregulatory physiology of sheep (Bligh, 1959(Bligh, , 1961(Bligh, , 1963 we wanted to know how well the sheep can thermoregulate under field conditions in all seasons of the year in Britain. Previous studies of the long-term pattern of body temperature of sheep in other climates (Minett & Sen, 1945; Symington, 1960;Eyal, 1963) have been subject to the experimental limitations mentioned above.…”

Physiological and chemical responses in water-deprived Awassi ewes treated with vitamin C

“…An increase in rectal temperature was reported under heat and water stress (Alamer and Al-hozab, 2004;Eyal, 1963;MacFarlane, 1964;Taneja, 1965) while others reported no variation in rectal temperature (Hamadeh et al, 2006;Jaber et al, 2004). The slight increase in rectal temperature may be an attempt to decrease water losses by evaporative cooling (Silanikove, 1992).…”