EFFECTS OF INGESTION OF WARM, COLD AND FROZEN WATER ON HEAT BALANCE IN CATTLE

1984 ◽  
Vol 64 (1) ◽  
pp. 73-80 ◽  
Author(s):  
A. A. DEGEN ◽  
B. A. YOUNG
Keyword(s):  
Thermal Stress ◽  
Metabolic Rate ◽  
Heat Production ◽  
Liquid Water ◽  
Heat Balance ◽  
Cold Water ◽  
Latin Square ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Snow And Ice

Four steers were used in a 4 × 4 latin-square-designed study that consisted of four 14-day periods and four water treatments. Once daily for 30 min, the steers were offered either snow, crushed ice, cold water (CW) near 0 °C or warm water (WW near 30 °C. These restricted water sources were offered 18 h after feeding to maximize possible thermal stress due to ingestion of the cold or frozen water. The snow and ice treatments reduced water intakes, rumen volume and dry matter of rumen contents. The maximum increment in metabolic heat production was observed with the ice treatment, 278% of preingestion metabolic rate, and this treatment also elevated metabolic rate for the longest time (182.5 min). The total increment in heat production by the steers was approximately 50% of the heat energy required to melt the snow or ice and raise the resultant water to body temperature. Minimal rumen temperatures were observed earlier than minimal rectal temperatures with the ice treatment resulting in the largest decrease in both rumen (16.5 °C) and rectal (1.4 °C) temperature. When offered choices of pairs of all combinations of snow, ice, CW and WW, the steers showed no preference for either the CW or WW. They preferred liquid water but would consume snow or ice when no liquid water was available. It was concluded that steers can tolerate thermal stress resulting from rapid ingestion of snow and ice drawing approximately equally from body heat and from increased metabolic heat production to compensate for the latent heat and heat of warming water. Key words: Cold water, heat balance, thermal stress, cattle, snow

scholarly journals Human thermoregulatory responses during serial cold-water immersions

1998 ◽  
Vol 85 (1) ◽  
pp. 204-209 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
Michael N. Sawka ◽  
Kent B. Pandolf
Keyword(s):  
Body Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Alternative Explanation ◽  
Cold Water ◽  
Metabolic Heat Production ◽  
Normal Body Temperature ◽  
Repeat Trial ◽  
Metabolic Heat ◽  
Made In

This study examined whether serial cold-water immersions over a 10-h period would lead to fatigue of shivering and vasoconstriction. Eight men were immersed (2 h) in 20°C water three times (0700, 1100, and 1500) in 1 day (Repeat). This trial was compared with single immersions (Control) conducted at the same times of day. Before Repeat exposures at 1100 and 1500, rewarming was employed to standardize initial rectal temperature. The following observations were made in the Repeat relative to the Control trial: 1) rectal temperature was lower and heat debt was higher ( P < 0.05) at 1100; 2) metabolic heat production was lower ( P < 0.05) at 1100 and 1500; 3) subjects perceived the Repeat trial as warmer at 1100. These data suggest that repeated cold exposures may impair the ability to maintain normal body temperature because of a blunting of metabolic heat production, perhaps reflecting a fatigue mechanism. An alternative explanation is that shivering habituation develops rapidly during serially repeated cold exposures.

Sex-Related Differences in Dynamic Heat Balance: Metabolic Heat Production Considerations

2008 ◽  
Vol 40 (Supplement) ◽  
pp. S336 ◽  
Author(s):  
Daniel Gagnon ◽  
Ollie Jay ◽  
Bruno Lemire ◽  
Lucy Dorman ◽  
Glen P. Kenny
Keyword(s):  
Heat Production ◽  
Heat Balance ◽  
Metabolic Heat Production ◽  
Metabolic Heat

scholarly journals Comparison of Electric Resistive Heating Pads and Forced-Air Warming for Pre-hospital Warming of Non-shivering Hypothermic Subjects

2019 ◽  
Author(s):  
Daryl M G Hurrie ◽  
Emily Hildebrand ◽  
Scott M Arnould ◽  
Jeremy Plett ◽  
Daniel Bellan ◽  
...  
Keyword(s):  
Heat Production ◽  
Cold Water ◽  
Total Heat ◽  
Metabolic Heat Production ◽  
Resistive Heating ◽  
Heat Gain ◽  
Metabolic Heat ◽  
Us Military ◽  
Forced Air Warming ◽  
Forced Air

Abstract Introduction Victims of severe hypothermia require external rewarming, as self-rewarming through shivering heat production is either minimal or absent. The US Military commonly uses forced-air warming in field hospitals, but these systems require significant power (600–800 W) and are not portable. This study compared the rewarming effectiveness of an electric resistive heating pad system (requiring 80 W) to forced-air rewarming on cold subjects in whom shivering was pharmacologically inhibited. Materials and Methods Shivering was inhibited by intravenous meperidine (1.5 mg/kg), administered during the last 10 min of cold-water immersion. Subjects then exited from the cold water, were dried and lay on a rescue bag for 120 min in one of the following conditions: spontaneous rewarming only (rescue bag closed); electric resistive heating pads (EHP) wrapped from the anterior to posterior torso (rescue bag closed); or, forced-air warming (FAW) over the anterior surface of the body (rescue bag left open and cotton blanket draped over warming blanket). Supplemental meperidine (to a maximum cumulative dose of 3.3 mg/kg) was administered as required during rewarming to suppress shivering. Results Six healthy subjects (3 m, 3 f) were cooled on three different occasions, each in 8°C water to an average nadir core temperature of 34.4 ± 0.6°C (including afterdrop). There were no significant differences between core rewarming rates (spontaneous; 0.6 ± 0.3, FAW; 0.7 ± 0.2, RHP; 0.6 ± 0.2°C/h) or post-cooling afterdrop (spontaneous; 1.9 ± 0.4, FAW; 1.9 ± 0.3, RHP; 1.6 ± 0.2°C) in any of the 3 conditions. There were also no significant differences between metabolic heat production (S; 74 ± 20, FAW; 66 ± 12, RHP; 63 ± 9 W). Total heat gain was greater with FAW (36 W gain) than EHP (13 W gain) and spontaneous (13 W loss) warming (p < 0.005). Conclusions Total heat gain was greater in FAW than both EHP, and spontaneous rewarming conditions, however, there were no observed differences found in rewarming rates, post-cooling afterdrop or metabolic heat production. The electric heat pad system provided similar rewarming performance to a forced-air warming system commonly used in US military field hospitals for hypothermic patients. A battery-powered version of this system would not only relieve pressure on the field hospital power supply but could also potentially allow extending use to locations closer to the field of operations and during transport. Such a system could be studied in larger groups in prospective trials on colder patients.

Psychrometric limits and critical evaporative coefficients for unacclimated men and women

2002 ◽  
Vol 92 (6) ◽  
pp. 2256-2263 ◽  
Author(s):  
W. Larry Kenney ◽  
Michael J. Zeman
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Heat Production ◽  
Heat Balance ◽  
Water Vapor Pressure ◽  
Metabolic Heat Production ◽  
Maximal Aerobic Capacity ◽  
Men And Women ◽  
Metabolic Heat ◽  
Environmental Limits

Critical environmental limits, defined as those above which heat balance cannot be maintained for a given metabolic heat production, have not been determined for unacclimated subjects. To characterize critical environmental limits and to derive evaporative heat exchange coefficients ( K e′) for unacclimated young men ( n = 11) and women ( n = 10), subjects of average aerobic fitness walked at 30% maximal aerobic capacity in an environmental chamber. Critical environmental conditions were defined as the psychrometric loci of dry-bulb temperature and water vapor pressure at which core (esophageal) temperature was forced out of equilibrium (heat gain exceeded heat loss). Compared with the men in our study, the women had significantly higher critical environmental limits ( P < 0.001) in warm (34–38°C), humid (>60%) environments, a function of their lower absolute metabolic heat production at the fixed relative exercise intensity. Isotherms constructed from biophysical models closely fit the data in this range of environments but underestimated empirically determined critical limits in hotter, drier environments. Sex-specific values of K e′ were derived by partial calorimetry in the critical water vapor pressure environments, in which full skin wettedness occurred. There were no sex differences for K e′ (men = 17.4, 15.5, and 14.2 W · m−2 · Torr−1 and women = 16.8, 15.5, and 14.2 W · m−2 · Torr−1 at 34, 36, and 38°C, respectively). These K e′ values were lower than those previously published for fully heat-acclimated men (18.4 W · m−2 · Torr−1 at 36°C) and women (17.7 W · m−2 · Torr−1 at 36°C and 15.5 W · m−2 · Torr−1 at 38°C) and may be used to model heat balance responses for unacclimated men and women working in hot environments.

Heat Balance and Distribution during the Core-Temperature Plateau in Anesthetized Humans

1995 ◽  
Vol 83 (3) ◽  
pp. 491-499. ◽  
Author(s):  
Andrea Kurz ◽  
Daniel I. Sessler ◽  
Richard Christensen ◽  
Martha Dechert
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Heat Production ◽  
Heat Balance ◽  
Thermal Flux ◽  
The Body ◽  
Metabolic Heat Production ◽  
The Core ◽  
Metabolic Heat ◽  
Temperature Plateau

Background Once triggered, intraoperative thermoregulatory vasoconstriction is remarkably effective in preventing further hypothermia. Protection results from both vasoconstriction-induced decrease in cutaneous heat loss and altered distribution of body heat. However, the independent contributions of each mechanism have not been quantified. Accordingly, we evaluated overall heat balance and distribution of heat within the body during the core-temperature plateau. Methods Nine minimally clothed male volunteers were anesthetized with propofol and isoflurane and maintained in an approximately 22 degrees C environment. They were monitored for approximately 2 h before vasoconstriction and for 3 h subsequently. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular temperatures, ten skin temperatures, and "deep" foot temperature. Heat constrained by vasoconstriction to the trunk and head was calculated by subtracting the expected change in that region (overall heat balance multiplied by the fractional weight of the trunk and head) from the actual change (change in distal esophageal temperature multiplied by the specific heat of human tissue and the weight of the trunk and head); the result represents the amount by which core heat exceeded that which would be expected based on overall heat balance, assuming that the change was evenly distributed throughout the body. Results Vasoconstriction and passive tissue cooling decreased heat loss but not to the level of heat production. Consequently, heat loss exceeded metabolic heat production throughout the study. Core temperature decreased approximately 1.3 C during the 2-h prevasoconstriction period; however, core temperature remained virtually constant during the subsequent 3 h. In the 3 h after vasoconstriction, arm and leg heat content decreased 57 +/- 9 kcal, and vasoconstriction constrained 22 +/- 8 kcal to the trunk and head. Conclusions These results confirm the efficacy of thermo-regulatory vasoconstriction in preventing additional core hypothermia. Decreased cutaneous heat loss and constraint of metabolic heat to the core thermal compartment contributed to the plateau.

scholarly journals Effects of complex radiative and convective environments on the thermal biology of the white-crowned sparrow (Zonotrichia leucophrys gambelii)

2000 ◽  
Vol 203 (4) ◽  
pp. 803-811 ◽  
Author(s):  
B.O. Wolf ◽  
K.M. Wooden ◽  
G.E. Walsberg
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Air Temperature ◽  
Heat Production ◽  
Heat Balance ◽  
Metabolic Heat Production ◽  
Wind Speeds ◽  
Metabolic Heat ◽  
Simulated Solar Radiation ◽  
Zonotrichia Leucophrys Gambelii

The energy budgets of small endotherms are profoundly affected by characteristics of the physical environment such as wind speed, air temperature and solar radiation. Among these, solar radiation represents a potentially very large heat load to small animals and may have an important influence on their thermoregulatory metabolism and heat balance. In this investigation, we examined the interactive effects of wind speed and irradiance on body temperature, thermoregulatory metabolism and heat balance in the white-crowned sparrow (Zonotrichia leucophrys gambelii). We measured changes in metabolic heat production by exposing birds to different wind speeds (0.25, 0.5, 1.0 and 2.0 m s(−1)) and irradiance combinations (&lt;3 W m(−2) and 936+/−11 W m(−2); mean +/− s.d.) at an air temperature of 10 degrees C. Body temperature was not affected by wind speed, but was significantly higher in animals not exposed to simulated solar radiation compared with those exposed at most wind speeds. In the absence of solar radiation, metabolic heat production was strongly affected by wind speed and increased by 30 % from 122 to 159 W m(−2) as wind speed increased from 0.25 to 2.0 m s(−1). Metabolic heat production was even more strongly influenced by wind speed in the presence of simulated solar radiation and increased by 51% from 94 to 142 W m(−2) as wind speed increased from 0.25 to 2. 0 m s(−1). Solar heat gain was negatively correlated with wind speed and declined from 28 to 12 W m(−2) as wind speed increased from 0.25 to 2.0 m s(−1) and, at its maximum, equaled 11% of the radiation intercepted by the animal. The overall thermal impact of the various wind speed and irradiance combinations on the animal's heat balance was examined for each treatment. Under cold conditions, with no solar radiation present, an increase in wind speed from 0.25 to 2.0 m s(−1) was equivalent to a decrease in chamber air temperature of 12.7 degrees C. With simulated solar radiation present, a similar increase in wind speed was equivalent to a decrease in chamber air temperature of 16 degrees C. Overall, shifting environmental conditions from a wind speed of 0.25 m s(−1) and irradiance of 936 W m(−2) to a wind speed of 2.0 m s(−1) with no short-wave radiation present was equivalent to decreasing chamber air temperature by approximately 20 degrees C. The sensitivity to changes in the convective environment, combined with the complex effects of changes in irradiance levels revealed by re-analyzing data published previously, significantly complicates the task of estimating the heat balance of animals in nature.

Thermal responses in humans exposed to cold hyperbaric helium-oxygen

1980 ◽  
Vol 49 (6) ◽  
pp. 1099-1106 ◽  
Author(s):  
C. A. Piantadosi ◽  
E. D. Thalmann
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Cold Water ◽  
Minute Ventilation ◽  
Water Immersion ◽  
Heat Losses ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Respiratory Heat Loss ◽  
Wide Range

The relationship of metabolic heat production to skin and core temperatures, cutaneous heat flow, and respiratory heat loss was measured in 10 male subjects cooled in hyperbaric helium at 20.7 ATA and 15 or 20 degrees C for 60-120 min. Under these conditions, metabolic heat production tended to compensate for the sum of convective and radiant heat losses from the skin but did not increase sufficiently to compensate for additional respiratory heat losses. There was a positive correlation between respiratory heat loss and fall in rectal temperature. Individual variability in ventilatory response to cold hyperbaric helium exposure as shown by a wide range of minute ventilation-to-oxygen consumption ratios (VE/VO2) was similar to that reported during cold water immersion. Subjects with high VE/VO2 had low mean physiological shell insulation values and lost more heat through the skin as well as through the respiratory tract than subjects with low VE/VO2.

scholarly journals Females Have An Increased Sensitivity To Thermal Stress During Matched Exercise Metabolic Heat Production

2020 ◽  
Vol 52 (7S) ◽  
pp. 853-853
Author(s):  
Lauren Schoech ◽  
Kyleigh Allie ◽  
Paolo Salvador ◽  
Mauricio Martinez ◽  
Eric Rivas
Keyword(s):  
Thermal Stress ◽  
Heat Production ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Increased Sensitivity

Physical fitness and thermoregulatory reactions in a cold environment in men

1988 ◽  
Vol 65 (5) ◽  
pp. 1984-1989 ◽  
Author(s):  
J. H. Bittel ◽  
C. Nonotte-Varly ◽  
G. H. Livecchi-Gonnot ◽  
G. L. Savourey ◽  
A. M. Hanniquet
Keyword(s):  
Physical Fitness ◽  
Cold Stress ◽  
Heat Production ◽  
Ambient Air ◽  
Metabolic Heat Production ◽  
Adult Males ◽  
Fitness Level ◽  
Metabolic Heat ◽  
Air Temperatures ◽  
Thermoregulatory Reactions

The relationship between the physical fitness level (maximal O2 consumption, VO2max) and thermoregulatory reactions was studied in 17 adult males submitted to an acute cold exposure. Standard cold tests were performed in nude subjects, lying for 2 h in a climatic chamber at three ambient air temperatures (10, 5, and 1 degrees C). The level of physical fitness conditioned the intensity of thermoregulatory reactions to cold. For all subjects, there was a direct relationship between physical fitness and 1) metabolic heat production, 2) level of mean skin temperature (Tsk), 3) level of skin conductance, and 4) level of Tsk at the onset of shivering. The predominance of thermogenic or insulative reactions depended on the intensity of the cold stress: insulative reactions were preferential at 10 degrees C, or even at 5 degrees C, whereas colder ambient temperature (1 degree C) triggered metabolic heat production abilities, which were closely related to the subject's physical fitness level. Fit subjects have more efficient thermoregulatory abilities against cold stress than unfit subjects, certainly because of an improved sensitivity of the thermoregulatory system.

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