Textbook of Environmental Physiology, 2nd Edition

Folk, G. Edgar; Dill, D. B.

doi:10.1249/00005768-197500720-00005

Cited by 35 publications

(40 citation statements)

References 0 publications

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“…1a-c). It remains possible that greater benefits of a spacer garment might be observed under conditions with greater laminar airflow ([1 m/s) or when performing movements and activities which create a greater ''chimney effect'' (Folk 1974). However, the external validity of our findings appears reasonable when considering that warm/hot ambient air forced across the torso must be substantial in flow (10-20 cfm) to reduce physiological strain demonstrably when protective clothing is worn (Muza et al 1988).…”

Section: Discussionmentioning

confidence: 99%

Impact of a protective vest and spacer garment on exercise-heat strain

et al. 2007

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Protective vests worn by global security personnel, and weighted vests worn by athletes, may increase physiological strain due to added load, increased clothing insulation and vapor resistance. The impact of protective vest clothing properties on physiological strain, and the potential of a spacer garment to reduce physiological strain, was examined. Eleven men performed 3 trials of intermittent treadmill walking over 4 h in a hot, dry environment (35°C, 30% rh). Volunteers wore the US Army battledress uniform (trial B), B + protective vest (trial P), and B + P + spacer garment (trial S). Biophysical clothing properties were determined and found similar to many law enforcement, industry, and sports ensembles. Physiological measurements included core (T c ), mean skin (T sk ) and chest (T chest ) temperatures, heart rate (HR), and sweating rate (SR). The independent impact of clothing was determined by equating metabolic rate in all trials. In trial P, HR was +7 b/min higher after 1 h of exercise and +19 b/min by the fourth hour compared to B (P \ 0.05). T c (+0.30°C), T sk (+1.0°C) and Physiological Strain Index were all higher in P than B (P \ 0.05). S did not abate these effects except to reduce T sk (P [ S) via a lower T chest (-0.40°C) (P \ 0.05). SR was higher (P \ 0.05) in P and S versus B, but the magnitude of differences was small. A protective vest increases physiological strain independent of added load, while a spacer garment does not alter this outcome.

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Section: Discussionmentioning

confidence: 99%

Impact of a protective vest and spacer garment on exercise-heat strain

et al. 2007

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“…Within this zone, minimal physiological cost and maximum productivity are normally achieved (Folk 1974). Body temperature is maintained by the thermoregulatory system within 1 C of its normal temperature under ambient conditions that do not impose heat stress (Bligh and Harthoorn 1965).…”

Section: Introductionmentioning

confidence: 99%

Thermoregulatory responses of Holstein and Brown Swiss Heat-Stressed dairy cows to two different cooling systems

Correa‐Calderón

Armstrong

Ray

et al. 2004

International Journal of Biometeorology

106

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Thirty-seven Holstein and 26 Brown Swiss dairy cows were used to evaluate the effect of two different cooling systems on physiological and hormonal responses during the summer. A control group of cows had access only to shade (C). A second group was cooled with spray and fans (S/F) and the third group was under an evaporative cooling system called Korral Kool (KK). The maximum temperature humidity index during the trial was from 73 to 85. Rectal temperatures and respiration rates of the C group were higher (P<0.05) than those of the S/F and KK groups in both Holstein and Brown Swiss cows. Triiodothyronine levels in milk were higher (P<0.05) in the KK group than in the S/F and C groups, while cortisol levels were lower (P<0.05) in the C group than in S/F and KK. There was no significant difference in the hormonal response of the two breeds. These results demonstrate that both cooling systems may be used increase the comfort of Holstein and Brown Swiss cows during summer in hot, dry climates.

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“…In response to these conditions, the cow will undertake various reactions to restore physiological integrity. When disruptive external stimuli threaten physiological steady state, homeostasis regulates animal processes (Folk, 1974). So in these extensive environments defined by a semiarid grassland environment, the cow's basal state is constantly challenged by change to which it reacts and attempts to stabilize for survival (Lee, 1965).…”

Section: Perceived Gaps In the 1996nrc Energetics Model Regarding Gramentioning

confidence: 99%

BEEF SPECIES SYMPOSIUM: Potential limitations of NRC in predicting energetic requirements of beef females within western U.S. grazing systems1,2

Petersen

Mueller

Mulliniks

et al. 2014

Journal of Animal Science

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Assessment of beef cow energy balance and efficiency in grazing-extensive rangelands has occurred on a nominal basis over short time intervals and has not accounted for the complexity of metabolic and digestive responses; behavioral adaptations to climatic, terrain, and vegetation variables; and documentation of the effects of nutrient form and supply to grazing cattle. Previous research using pen-fed cows demonstrated differences (P < 0.01) in efficiency of weight change ranging from 135 to 58 g/Mcal ME intake. Furthermore, variation in efficiency of ME use for tissue energy gain or loss ranged from 36% to 80%. In general, energy costs for maintenance, tissue accretion, and mobilization were greatest in Angus-based cows, intermediate in Brahmanand Hereford-based cows, and least in dairy-based cows. The most efficient cattle may reflect the types that are successful in semiarid grazing environments with low input management. Successful range cattle systems are likely the result of retention of animals that best adapted to the grazing environment and thus were potentially more efficient. Animals exposed to a variety of stressors may continually adapt, so energy expenditure is reduced and may tend to depart from the modeled beef cow in the 1996 NRC Beef Cattle Requirements. Critical factors comprising cow lifetime achievement, including reproductive success, disease resistance, and calf weaning weight, may be driven by cow total energy utilization in energy-limiting environments. Therefore, energy adjustments for adapted cattle within these landscapes and seasonal BW changes can alter seasonal NE m requirements. Evaluated studies indicate that in static grazing environments, NRC prediction fitness was improved compared with predictions from dynamic systems where cattle were influenced less by management and more by environmental conditions. Preliminary herd analyses cast doubt on the accuracy of NRC BCS descriptions representing NE m requirements of adapted females utilizing semiarid rangelands. Possible gaps are proposed that could be the basis for prediction inaccuracies. A more complete understanding of mechanisms contributing to productivity in the field than the current model predicts will improve future models to better simulate energetic accountability and subsequent female performance.

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Textbook of Environmental Physiology, 2nd Edition

Cited by 35 publications

References 0 publications

Impact of a protective vest and spacer garment on exercise-heat strain

Impact of a protective vest and spacer garment on exercise-heat strain

Thermoregulatory responses of Holstein and Brown Swiss Heat-Stressed dairy cows to two different cooling systems

BEEF SPECIES SYMPOSIUM: Potential limitations of NRC in predicting energetic requirements of beef females within western U.S. grazing systems1,2

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