Heat Production and Thermoregulatory Responses of Sheep Fed Different Roughage Proportion Diets and Intake Levels When Exposed to a High Ambient Temperature

Cold exposure elicits several thermoregulatory responses, including an increased metabolic heat production from shivering and nonshivering thermogenesis. The increased metabolism can be in response to body core and/or body cutaneous cooling. Hypoxic hypoxia has been shown to attenuate the metabolic response to cutaneous cooling. We measured metabolic heat production in adult conscious rats during independent cutaneous and core cooling, during normoxia and hypoxia, to 1) test the hypothesis that hypoxia suppresses the metabolic response to independent core cooling and 2) determine whether hypoxia acts preferentially on the response to cutaneous or core cooling. The animals were studied in a temperature-controlled metabolic chamber, and body core temperature was controlled by an abdominal heat exchange coil. Ambient temperature was varied (10, 19, and 28 degrees C) while core temperature was clamped at 37 degrees C or core temperature was varied (33, 35, and 37 degrees C) at a stable ambient temperature of 28 degrees C. Our data indicate that although the sensitivity of the metabolic response to core cooling is about five to six times that to cutaneous cooling. Hypoxia similarly attenuates thermoregulatory responses to both stimuli.

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Effects of short-term exposure to high ambient temperature and relative humidity on thermoregulatory responses of European (Large White) and Caribbean (Creole) restrictively-fed growing pigs

Animal Research ◽

10.1051/animres:2005005 ◽

2005 ◽

Vol 54 (2) ◽

pp. 81-93 ◽

Cited By ~ 16

Author(s):

David Renaudeau

Keyword(s):

Relative Humidity ◽

Ambient Temperature ◽

Growing Pigs ◽

High Ambient Temperature ◽

Short Term ◽

Large White ◽

Thermoregulatory Responses ◽

Short Term Exposure

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Partial submergence: An undescribed behavioral adjustment for thermoregulation at high ambient temperature in Aeshnidae

International Journal of Odonatology ◽

10.23797/2159-6719_24_5 ◽

2021 ◽

Vol 24 ◽

pp. 71-81

Author(s):

Pierre Deviche

Keyword(s):

Ambient Temperature ◽

Heat Loss ◽

Heat Production ◽

Sonoran Desert ◽

Heat Dissipation ◽

High Ambient Temperature ◽

Physiological Mechanisms ◽

Anax Junius ◽

Daily Difference ◽

Thermoregulatory Function

Many insects including odonates thermoregulate using a combination of behavioral and physiological mechanisms. At high ambient temperature (Ta), these mechanisms include decreased heat production and increased heat loss. Heat production can be reduced by decreasing activity. Heat loss can be enhanced by perching in a shaded microhabitat where temperature is cooler than in the surrounding environment. Aeshnids, which are intermittent endotherms, increase heat loss at high Ta; also by increasing hemolymph circulation from the thorax, where most metabolic heat is produced, to the abdomen, where it dissipates to the environment by convection. While studying two aeshnid species (Anax junius and Rhionaeschna multicolor) at a Sonoran Desert (Arizona, USA) stream, I observed partially submerged mature individuals of both sexes of these species. This heretofore undescribed behavior was seen only at Ta; ≥ 43 °C and almost exclusively during the hottest part of the day (15:00–17:00 hr), when the daily difference between Ta; and water temperature (Tw) was, on average, largest. A cooling effect of partial submergence behavior on body temperature would, therefore, presumably be most effective also during this period. Several percher species of libellulids were present at the study site. These dragonflies are not known to use endothermy for thermoregulation or to increase hemolymph circulation to the abdomen to dissipate heat at high Ta;, and none was ever observed to partially submerge. It is suggested in aeshnids that partial submergence at high Ta; serves a thermoregulatory function by facilitating body heat dissipation from the abdomen.

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Effects of Thermal Conditioning on Changes in Hepatic and Muscular Tissue Associated With Reduced Heat Production and Body Temperature in Young Chickens

Frontiers in Veterinary Science ◽

10.3389/fvets.2020.610319 ◽

2021 ◽

Vol 7 ◽

Author(s):

Yoshimitsu Ouchi ◽

Vishwajit S. Chowdhury ◽

John F. Cockrem ◽

Takashi Bungo

Keyword(s):

Body Temperature ◽

Ambient Temperature ◽

Heat Production ◽

Uncoupling Protein ◽

High Ambient Temperature ◽

Acid Oxidation ◽

Broiler Chicks ◽

Muscular Tissue ◽

Poultry Production ◽

Ambient Temperatures

Effects of increased summer temperatures on poultry production are becoming more pronounced due to global warming, so it is important to consider approaches that might reduce heat stress in chickens. Thermal conditioning in chickens in the neonatal period can improve thermotolerance and reduce body temperature increases when birds are exposed to high ambient temperature later in life. The objective of this study was to investigate physiological and molecular changes associated with heat production and hence body temperature regulation under high ambient temperatures in thermally conditioned chicks. Three-day-old broiler chicks (Chunky) were thermally conditioned by exposure to a high ambient temperature (40°C) for 12 h while control chicks were kept at 30°C. Four days after the treatment, both groups were exposed to 40°C for 15 or 90 min. The increase in rectal temperature during 90 min of exposure to a high ambient temperature was less in thermally conditioned than control chicks. At 15-min of re-exposure treatment, gene expression for uncoupling protein and carnitine palmitoyletransferase 1, key molecules in thermogenesis and fatty acid oxidation, were significantly higher in pectoral muscle of control chicks but not conditioned chicks. Hepatic argininosuccinate synthase (ASS) decreased and hepatic argininosuccinate lyase (ASL) increased after reexposure to a high temperature. The concentrations of hepatic arginosuccinic acid, and ASS and ASL expression, were upregulated in conditioned chicks compared with the control chicks, indicating activity of the urea cycle could be enhanced to trap more energy to reduce heat production in conditioned chicks. These results suggest thermal conditioning can reduce the increase in heat production in muscles of chickens that occurs in high ambient temperatures to promote sensible heat loss. Conditioning may also promote energy trapping process in the liver by altering the heat production system, resulting in an alleviation of the excessive rise of body temperature.

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