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1
Gurney, Shae C., Katherine S. Christison, Tyler Stenersen, and Charles L. Dumke. "Effect of uncompensable heat from the wildland firefighter helmet." International Journal of Wildland Fire 30, no. 12 (2021): 990. http://dx.doi.org/10.1071/wf20181.
Повний текст джерелаАнотація:
Heat accumulation from wearing personal protective equipment can result in the development of heat-related illnesses. This study aimed to investigate factors of heat stress with and without a US standard issue wildland firefighter helmet. Ten male subjects finished a 90-min exercise protocol in a heat chamber (35°C and 30% relative humidity), with standard issue meta-aramid shirt and pants and a cotton t-shirt, and either with or without a wildland firefighter helmet. A randomised crossover design was implemented, with a minimum 2-week washout period. Heart rate, physiologic strain index, perceived head heat, head heat and skin blood flow of the head and neck were measured. At the conclusion of the 90-min trial, heart rate, physiological strain index, core temperature, rating of perceived exertion and perceived head heat showed a main effect of time (P < 0.05). Perceived head heat and head heat exhibited a main effect of trial (P < 0.05). The change in physiologic strain was positively correlated with the change in skin blood flow of the head (r = 0.72, P = 0.02). These data suggest that the current wildland firefighter helmet contributes to heat accumulation. The design of the wildland firefighter helmet lacks ventilation, which, from these data, may result in metabolic alterations and perceived discomfort.
2
Jumnake, Aishvarya R., Vishwambhar R.Patodkar, Vikas M.Sardar, Prajwalini V.Mehere, Sameer N.Jadhav, and Sachin S. Pawar. "Effect of Heat Stress on Physiological Parameters in Madgyal Sheep." UTTAR PRADESH JOURNAL OF ZOOLOGY 45, no. 14 (June 27, 2024): 164–69. http://dx.doi.org/10.56557/upjoz/2024/v45i144190.
Повний текст джерелаАнотація:
The current study was carried out to assess the impact of heat stress on physiological parameters in Madgyal Sheep. To investigate this, sheep were exposed to 0,4 and 8 hrs heat of direct sunlight during grazing in 3 different Groups Viz A, B and C. The study was conducted on Day 0, Day 15 and Day 30 of the experiment to observe the effect of different duration of heat exposure on all physiological parameters. The temperature humidity index (THI) values duting the experimental period were found to be (76.28+-0.81) The results of the statistical analysis showed that there was no significant difference group wise and day wise in the Rectal temperature. However, the Respiration Rate, Pulse Rate and Heart Rate in Group wise comparison showed a significant difference (P<0.05) with increasing trend. In Day wise comparison of Respiratory Rate there was no significant difference at different days in Group A & B. However, there was a significance difference (P<0.05) in group C at different days with increasing trend. Pulse Rate and Heart rate Day wise comparison showed no significant difference at different days in Group A and C while there was a significant difference at different days in Group B with higher values at Day 15 and Day 30 as compared to at Day 0.
3
Wojtas, Krzysztof, Przemysław Cwynar, and Roman Kołacz. "Effect of thermal stress on physiological and blood parameters in merino sheep." Bulletin of the Veterinary Institute in Pulawy 58, no. 2 (June 1, 2014): 283–88. http://dx.doi.org/10.2478/bvip-2014-0043.
Повний текст джерелаАнотація:
Abstract Fifteen sheep where placed in climatic chamber and exposed to a high temperature (30°C). Then, the air movement was induced in order to examine its soothing effect on heat stress. The physiological reactions like respiratory and heart rates, as well as the morphologic, biochemical parameters and cortisol levels in blood were examined. It was found that under heat stress conditions, the respiratory rate increased up to 96.43 breaths/min, heart rate up to 107.79 beats/min, and white blood cells count decreased to 9.12 k/μL. The increased level of potassium, chlorine, and calcium was also observed. The increased air movement resulted in thermal stress soothing. A decrease in respiratory rate, heart rate, and cortisol concentration was observed. The study demonstrated that heat stress leads to serious changes in physiological and blood parameters in sheep but this effect can be minimised by air movement.
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The, Enos, M. Jen Wajo, and M. A. Muin. "Respon fisiologis dan hematologis Kambing peranakan Etawah terhadap cekaman panas." Cassowary 1, no. 1 (January 6, 2018): 63–74. http://dx.doi.org/10.30862/casssowary.cs.v1.i1.6.
Повний текст джерелаАнотація:
PE goat is a small ruminant crossed between Etawah goat and bean goat, which introduced in Manokwari since 2007. Livestock can well produce depend on environment comfortable temperature in the area of tropical temperature on the day is radiated in high sun light. If the goat is expose to the blazing sun, it supposed experiencing heat stress and caused to the physiological and haematological condition. The aim of this study is to know the physiological and haematological response of PE goat to heat stress. This design of research used is Split Plot (RPT). 8 goats will be a sample which devide in two groups, of unexposed groups and Groups exposed to sunlight. Each group consists of young males, young female, adult male, adult female. The variables observed included physiological aspects (heart rate, rectal temperature, respiratory rate) and haematological aspects (hemoglobin level, hematocrit value, erythrocyte count, leukocyte count). The results showed that interaction between goats and heat stress status did not influence physiological aspect variable (heart rate, rectal temperature, respiratory rate), but very significant effect on some hematological aspect variable such as hemoglobin and erythrocytes. The status of livestock has a very significant effect on some physiological aspect variable such as rectal temperature, respiratory rate) and hematological aspect variable ie hemoglobin, hematocrit and erythrocytesTreatment of heat stress has a very significant effect on the physiological aspects of variables such as heart rate, rectal temperature and respiration whereas on hematologic aspect variable have significant effect on hemoglobin level, very significant effect on hematocrit value and erythrocyte level.
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Morito, Akihisa, Takayuki Inami, Akihiro Hirata, Satoshi Yamada, Masatsugu Shimomasuda, Keita Kato, Shigeyuki Tahara, and Naohiko Kohtake. "Effect of Ice Slurry Ingestion on Post-Exercise Physiological Responses in Rugby Union Players." Physiologia 2, no. 4 (November 5, 2022): 154–63. http://dx.doi.org/10.3390/physiologia2040013.
Повний текст джерелаАнотація:
Delayed recovery of the core body temperature after exercise adversely affects physiological functions, and the effects of ingesting lower-temperature ice slurry on post-exercise recovery remain unclear. We investigated the effects of ingesting −2 °C ice slurry on physiological recovery after field-based rugby union training. Fifteen university rugby union players participated in our randomized controlled study. The players participated in the training for 60 min in a hot outdoor environment (wet-bulb globe temperature, 30.5 °C). Physiological responses were measured during a physical performance test performed after the players ingested either −2 °C-ice slurry (ICE, N = 7) at 5 g/kg body mass or a 30 °C-fluid (CON, N = 8) during the 15 min recovery period after the training. Tympanic temperatures and heart rates were measured as the physiological indices, as well as heat storage. The ICE group showed significantly decreased tympanic temperatures and heart rates (p < 0.05) during the recovery period and increased heat storage (p < 0.05) but did not show improvement of physiological indices during the performance test compared to the CON group. These results suggest that ingestion of −2 °C ice slurry in even lower amounts than those previously reported is useful for physiological recovery after training in hot outdoor environments.
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Amézaga González, María Fernanda, Jazzely Acosta Bezada, Víctor Gómez Flores, Christian Chapa González, Jose Rurik Farias Mancilla, S. J. Castillo, Carlos Avila Orta, and Perla E. García-Casillas. "Effect of Physiological Fluid on the Photothermal Properties of Gold Nanostructured." International Journal of Molecular Sciences 24, no. 9 (May 6, 2023): 8339. http://dx.doi.org/10.3390/ijms24098339.
Повний текст джерелаАнотація:
Colloidal gold particles have been extensively studied for their potential in hyperthermia treatment due to their ability to become excited in the presence of an external laser. However, their light-to-heat efficiency is affected by the physiologic environment. In this study, we aimed to evaluate the ability of gold sphere, rod, and star-shaped colloids to elevate the temperature of blood plasma and breast cancer-simulated fluid under laser stimulation. Additionally, the dependence of optical properties and colloid stability of gold nanostructures with physiological medium, particle shape, and coating was determined. The light-to-heat efficiency of the gold particle is shape-dependent. The light-to-heat conversion efficiency of a star-shaped colloid is 36% higher than that of sphere-shaped colloids. However, the raised temperature of the surrounding medium is the lowest in the star-shaped colloid. When gold nanostructures are exited with a laser stimulation in a physiological fluid, the ions/cations attach to the surface of the gold particles, resulting in colloidal instability, which limits electron oscillation and diminishes the energy generated by the plasmonic excitation. Fluorescein (Fl) and polyethylene glycol (PEG) attached to gold spheres enhances their colloidal stability and light-to-heat efficiency; post-treatment, they remand their optical properties.
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Bröde, Peter, and Bernhard Kampmann. "Temperature–Humidity-Dependent Wind Effects on Physiological Heat Strain of Moderately Exercising Individuals Reproduced by the Universal Thermal Climate Index (UTCI)." Biology 12, no. 6 (May 31, 2023): 802. http://dx.doi.org/10.3390/biology12060802.
Повний текст джерелаАнотація:
Increasing wind speed alleviates physiological heat strain; however, health policies have advised against using ventilators or fans under heat wave conditions with air temperatures above the typical skin temperature of 35 °C. Recent research, mostly with sedentary participants, suggests mitigating the effects of wind at even higher temperatures, depending on the humidity level. Our study aimed at exploring and quantifying whether such results are transferable to moderate exercise levels, and whether the Universal Thermal Climate Index (UTCI) reproduces those effects. We measured heart rates, core and skin temperatures, and sweat rates in 198 laboratory experiments completed by five young, semi-nude, heat-acclimated, moderately exercising males walking the treadmill at 4 km/h on the level for three hours under widely varying temperature–humidity combinations and two wind conditions. We quantified the cooling effect of increasing the wind speed from 0.3 to 2 m/s by fitting generalized additive models predicting the physiological heat stress responses depending on ambient temperature, humidity, and wind speed. We then compared the observed wind effects to the assessment performed by the UTCI. Increasing the wind speed lowered the physiological heat strain for air temperatures below 35 °C, but also for higher temperatures with humidity levels above 2 kPa water vapor pressure concerning heart rate and core temperature, and 3 kPa concerning skin temperature and sweat rate, respectively. The UTCI assessment of wind effects correlated positively with the observed changes in physiological responses, showing the closest agreement (r = 0.9) for skin temperature and sweat rate, where wind is known for elevating the relevant convective and evaporative heat transfer. These results demonstrate the potential of the UTCI for adequately assessing sustainable strategies for heat stress mitigation involving fans or ventilators, depending on temperature and humidity, for moderately exercising individuals.
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M.C., Narendra, Chandan Roy, Sudhir Kumar, Parminder Virk, and Nitish De. "Effect of terminal heat stress on physiological traits, grain zinc and iron content in wheat (Triticum aestivum L.)." Czech Journal of Genetics and Plant Breeding 57, No. 2 (April 9, 2021): 43–50. http://dx.doi.org/10.17221/63/2020-cjgpb.
Повний текст джерелаАнотація:
Heat stress is one of the major wheat (Triticum aestivum) production constraints in South Asia (SA), particularly in the Eastern Gangetic Plains (EGP) of India and Bangladesh. Malnutrition is also a severe problem among children and women in SA. Wheat varieties with high grain Zn/Fe are a sustainable, cost-effective solution in the fight against hidden hunger. Thirty wheat genotypes were characterised under the optimum temperature and heat stress conditions in 2016–2017 and 2017–2018 to study the response of the stress on the yield, physiological traits and grain Zn/Fe content. A significant genetic variation was observed for all the traits under the optimum temperature and stress conditions. The yield was reduced by an average of 59.5% under heat stress compared to that of the optimum temperature. A strong positive association of the canopy temperature depression (CTD) with the grain yield (GY) was observed under the heat stress. A negative correlation of the grain Zn/Fe with the yield was observed under the optimum temperature and heat stress conditions, while the association between the grain Zn and Fe was positive. The genotypes BRW 3723, BRW 3759, BRW 3797, BRW 160, HD 2967, HD 2640 were found to be heat-tolerant in both years. Among the tolerant genotypes, BRW 934, BRW 3807 and BRW 3804 showed a high zinc content and BRW 934, BRW 3797, BRW 3788 and BRW 3807 showed a high iron content, respectively. These genotypes can be explored in future breeding programmes to address the problem of nutritional deficiency.
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Ioannou, Leonidas G., Konstantinos Mantzios, Lydia Tsoutsoubi, Zoe Panagiotaki, Areti K. Kapnia, Ursa Ciuha, Lars Nybo, Andreas D. Flouris, and Igor B. Mekjavic. "Effect of a Simulated Heat Wave on Physiological Strain and Labour Productivity." International Journal of Environmental Research and Public Health 18, no. 6 (March 15, 2021): 3011. http://dx.doi.org/10.3390/ijerph18063011.
Повний текст джерелаАнотація:
Background: The aim of the study was to investigate the effect of a simulated heat-wave on the labour productivity and physiological strain experienced by workers. Methods: Seven males were confined for ten days in controlled ambient conditions. A familiarisation day was followed by three (pre, during, and post-heat-wave) 3-day periods. During each day volunteers participated in a simulated work-shift incorporating two physical activity sessions each followed by a session of assembly line task. Conditions were hot (work: 35.4 °C; rest: 26.3 °C) during, and temperate (work: 25.4 °C; rest: 22.3 °C) pre and post the simulated heat-wave. Physiological, biological, behavioural, and subjective data were collected throughout the study. Results: The simulated heat-wave undermined human capacity for work by increasing the number of mistakes committed, time spent on unplanned breaks, and the physiological strain experienced by the participants. Early adaptations were able to mitigate the observed implications on the second and third days of the heat-wave, as well as impacting positively on the post-heat-wave period. Conclusions: Here, we show for first time that a controlled simulated heat-wave increases workers’ physiological strain and reduces labour productivity on the first day, but it promotes adaptations mitigating the observed implications during the subsequent days.
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Qisthon, Arif, and Yusuf Widodo. "PENGARUH PENINGKATAN RASIO KONSENTRAT DALAM RANSUM KAMBING PERANAKAN ETTAWAH DI LINGKUNGAN PANAS ALAMI TERHADAP KONSUMSI RANSUM, RESPONS FISIOLOGIS, DAN PERTUMBUHAN." ZOOTEC 35, no. 2 (August 18, 2015): 351. http://dx.doi.org/10.35792/zot.35.2.2015.9275.
Повний текст джерелаАнотація:
ABSTRACT EFFECTS OF INCREASING CONCENTRATE RATIO IN THE RATION OF PERANAKAN ETTAWAH GOAT UNDER NATURAL HEAT ENVIRONMENT ON FEED INTAKE, PHYSIOLOGICAL RESPONSES, AND GROWTH. The research was conducted to study the effect of increasing the proportion of concentrate in the ration of Peranakan Ettawah (PE) goats. Animals were maintained in a natural hot environment on feed consumption, physiological responses, and body weight gain. The study used three male goats of PE in Latin Square design. Treatment applied was an increase in the proportion of concentrate in three forage-concentrate ratio (F:C), R1 = 85:15%; R2 = 70:30%; and R3 = 55:45%. The results showed that the treatment ratio of F:C had no effect (P> 0.05) in feed intake, respiration rate, rectal temperature, and body weight gain. In contrast, treatment affected significantly (P <0.05) heart rate, as follows R1 vs. R2 and R1 vs. R3, whereas R2 and R3 were not significantly different (P> 0.05). Keywords: Rations, heat stress, physiological, goat
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Liu, Binyi, Zefeng Lian, and Robert D. Brown. "Effect of Landscape Microclimates on Thermal Comfort and Physiological Wellbeing." Sustainability 11, no. 19 (September 29, 2019): 5387. http://dx.doi.org/10.3390/su11195387.
Повний текст джерелаАнотація:
Global climate change and intensifying heat islands have reduced human thermal comfort and health in urban outdoor environments. However, there has been little research that has focused on how microclimates affect human thermal comfort, both psychologically and physiologically. We investigated the effect of a range of landscape microclimates on human thermal comfort and health using questionnaires and physiological measurements, including skin temperature, skin conductance, and heart rate variability, and compared the results with the effect of prevailing climate conditions in open spaces. We observed that in landscape microclimates, thermal sensation votes significantly decreased from 1.18 ± 0.66 (warm–hot) to 0.23 ± 0.61 (neutral–slightly warm), and thermal comfort increased from 1.18 ± 0.66 (uncomfortable–neutral) to 0.23 ± 0.61 (neutral–comfortable). In the landscape microclimates, skin temperature and skin conductance decreased 0.3 ± 0.8 °C and 0.6 ± 1.0 μs, respectively, while in the control, these two parameters increased by 0.5 ± 0.9 °C and 0.2 ± 0.7 μs, respectively. Further, in landscape microclimates, subject heart rate variability increased significantly. These results suggest landscape microclimates improve human thermal comfort and health, both psychologically and physiologically. These findings can provide an evidence base that will assist urban planners in designing urban environments for the health and wellbeing of residents.
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Balla, K., I. Karsai, S. Bencze, T. Kiss, and O. Veisz. "Effect of heat stress on the physiological processes of wheat." Acta Agronomica Hungarica 61, no. 1 (March 1, 2013): 1–12. http://dx.doi.org/10.1556/aagr.61.2013.1.1.
Повний текст джерелаАнотація:
Stress tolerance is associated with the activation of antioxidant compounds and enzyme systems that are capable of neutralising the reactive oxygen species (ROS) continually produced in response to stress. The present experiment was designed to compare the heat tolerance of four winter wheat varieties in the shooting and grain-filling stages by investigating changes detected in antioxidant enzyme activity and yield components in response to heat stress.Heat treatment was found to cause a significant rise in the activity of the glutathione-S-transferase and catalase enzymes, while there was usually a less intense decline in the activity of guaiacol peroxidase.An analysis of yield data revealed that heat stress had a more pronounced effect during grain filling in this experiment than at the beginning of shooting, as shown by the greater reduction in thousand-kernel weight and yield.
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Alam, MM, MA Hashem, MM Rahman, MM Hossain, MR Haque, Z. Sobhan, and MS Islam. "Effect of Heat Stress on Behavior, Physiological and Blood Parameters of Goat." Progressive Agriculture 22, no. 1-2 (September 25, 2013): 37–45. http://dx.doi.org/10.3329/pa.v22i1-2.16465.
Повний текст джерелаАнотація:
The research was conducted to study the effect of heat stress on behavior, some physiological and blood parameters with nine goats of almost similar in age, sex and weight into three groups. Three groups were divided as zero hour (T0), four hours (T4) and eight hours (T8) heat exposure. Temperaturehumidity index (THI) value was calculated as 28.17 which indicate the experimental animals were in extreme severe heat stress. Skin and rectal temperature had no significant differences among the treatment groups but respiration/panting and pulse rate were increased with the increased of heat stress from T0 to T8 group (P<0.01). Significant difference was found in standing time and lying time (P<0.01) in experimental groups. There were significant changes (P<0.01) in number of urination and defecation per hour but no significant changes was found in duration per urination in heat treated groups. The amount of RBC, PCV%, Hb%, WBC were increased with the increased of heat stress (P<0.01). Neutrophil, eosinophil, lymphocyte and monocyte numbers increased significantly (P<0.01) in heat treated groups. It can be concluded that heat stress had significant changes on some behavioral, physiological and blood parameters of goat.DOI: http://dx.doi.org/10.3329/pa.v22i1-2.16465 Progress. Agric. 22(1 & 2): 37 - 45, 2011
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Yu, Yong Jiang, Jian Guo Tan, Hong Wang, and Chang Cheng Lin. "The Effect of Relative Humidity on Physiological Equivalent Temperature in Hot Environment." Advanced Materials Research 779-780 (September 2013): 1266–71. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1266.
Повний текст джерелаАнотація:
The important meteorological parameter affecting the human energy balance in heat strain condition is the relative humidity. The aim of this paper is to investigate the effect of relative humidity on human heat comfort. In this paper, the physiological equivalent temperature (PET) calculating program was corrected. The relationship between PET and relative humiditythermal state of human body on a typical hot day was analyzed. The results show that: Sweating is the most effective thermoregulatory process when the body is in a condition of heat strain; High water vapor pressure can restrain sweat evaporation and effect human heat balance in hot environment; The PET value increases rapidly as relative humidity over "threshold value" in hot environment, and the "threshold value" is different in various heat stain condition; The PET calculated by modified program agrees well with heat thermal sensation of people in hot-humidity environment.
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Vujanac, Ivan, Danijela Kirovski, Jovan Bojkovski, Radisa Prodanovic, Bozidar Savic, and Horea Samanc. "Effect of heat stress on vital signs in high-yield dairy cows." Veterinarski glasnik 64, no. 1-2 (2010): 53–63. http://dx.doi.org/10.2298/vetgl1002053v.
Повний текст джерелаАнотація:
The objective of this work was to examine the influence of outer temperature on values of the vital signs (temperature, pulse, respiration) in high-yield dairy cows in early stages of lactation, as well as to establish, on the grounds of the degree of correlation between the values for the vital signs and the temperature humidity index (THI), possibilities for using the examined physiological parameters of the organism as an indicator of heat stress. The experiment covered 10 high-yield dairy cows in the first phase of lactation. The investigations were carried out in the course of July and the first half of August. During the course of the experiment, the average THI was determined daily. An average daily THI higher than 70 indicated that the animal had been exposed to heat stress on that day. Vital signs were measured on twelve occasions during the period of investigation (June 30, July 4, July 7, July 10, July 14, July 17, July 21, July 24, July 29, August 5, August 11, and August 14). It was established on the grounds of the THI values that the examined animals were exposed to heat stress on June 30, July 4, July 7, July 14, July 17, July 21, July 29, August 5, and August 14, while there was no heat stress on July 10, July 24, and August 11. The average body temperature during all the periods of examination, with the exception of July 24, was above the upper physiological limit. A high degree of correlation was established between body temperature and the heat index (r = +0. 509; p = 0.05). The number of respiratory movements per minute was above the physiological values during the entire period of investigation. There was a high degree of correlation between the number of respiratory movements and THI (r = + 0.625; p<0.05). The average pulse values and number of contractions of the rumen did not vary significantly during the period of investigation. No significant correlation was established between the pulse and THI values, or between motoric activities of the rumen and THI. The results obtained in this work demonstrate that, in high-yield dairy cows exposed to moderate heat stress, the body temperature and the number of respiratory movements are above physiologically permitted values. On these grounds, it can be concluded that these two parameters of the vital signs can be used as physiological indicators of heat stress. .
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Hascall, Jessie L., Jay H. Heaney, Courtney L. Cowan, Paul W. Miller, and James A. Hodgdon. "Physiological Effect of the RTX During Exercise in the Heat." Medicine & Science in Sports & Exercise 40, Supplement (May 2008): S237. http://dx.doi.org/10.1249/01.mss.0000322513.32689.be.
Повний текст джерела
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Guliyeva, K. "Feeding of Cows for Different Physiological Groups." Bulletin of Science and Practice, no. 7 (July 15, 2023): 179–83. http://dx.doi.org/10.33619/2414-2948/92/25.
Повний текст джерелаАнотація:
The consumption of dry matter in animals adapted to heat stress as a result of feeding with a complex of bioactive compounds and their effect on metabolic processes was studied. The effect of feed additives on the milk productivity of cows, the quality of milk and the fatness of cows during the period of adaptation to heat stress was studied. The Flavo Vital complex of bioactive compounds was used as an additive, as well as corn silage, dry clover grass, barley, wheat bran, sifted wheat, soybean meal, corn grain and husk.
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Sekiguchi, Yasuki, Erica M. Filep, Courteney L. Benjamin, Douglas J. Casa, and Lindsay J. DiStefano. "Does Dehydration Affect the Adaptations of Plasma Volume, Heart Rate, Internal Body Temperature, and Sweat Rate During the Induction Phase of Heat Acclimation?" Journal of Sport Rehabilitation 29, no. 6 (August 1, 2020): 847–50. http://dx.doi.org/10.1123/jsr.2019-0174.
Повний текст джерелаАнотація:
Clinical Scenario: Exercise in the heat can lead to performance decrements and increase the risk of heat illness. Heat acclimation refers to the systematic and gradual increase in exercise in a controlled, laboratory environment. Increased duration and intensity of exercise in the heat positively affects physiological responses, such as higher sweat rate, plasma volume expansion, decreased heart rate, and lower internal body temperature. Many heat acclimation studies have examined the hydration status of the subjects exercising in the heat. Some of the physiological responses that are desired to elicit heat acclimation (ie, higher heart rate and internal body temperature) are exacerbated in a dehydrated state. Thus, euhydration (optimal hydration) and dehydration trials during heat acclimation induction have been conducted to determine if there are additional benefits to dehydrated exercise trials on physiological adaptations. However, there is still much debate over hydration status and its effect on heat acclimation. Clinical Question: Does dehydration affect the adaptations of plasma volume, heart rate, internal body temperature, skin temperature, and sweat rate during the induction phase of heat acclimation? Summary of Findings: There were no observed differences in plasma volume, internal body temperature, and skin temperature following heat acclimation in this critically appraised topic. One study found an increase in sweat rate and another study indicated greater changes in heart rate following heat acclimation with dehydration. Aside from these findings, all 4 trials did not observe statistically significant differences in euhydrated and dehydrated heat acclimation trials. Clinical Bottom Line: There is minimal evidence to suggest that hydration status affects heat acclimation induction. In the studies that met the inclusion criteria, there were no differences in plasma volume concentrations, internal body temperature, and skin temperature. Strength of Recommendation: Based on the Oxford Centre for Evidence-Based Medicine Scale, Level 2 evidence exists.
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McCleave, Erin L., Katie M. Slattery, Rob Duffield, Philo U. Saunders, Avish P. Sharma, Stephen Crowcroft, and Aaron J. Coutts. "Impaired Heat Adaptation From Combined Heat Training and “Live High, Train Low” Hypoxia." International Journal of Sports Physiology and Performance 14, no. 5 (May 1, 2019): 635–43. http://dx.doi.org/10.1123/ijspp.2018-0399.
Повний текст джерелаАнотація:
Purpose: To determine whether combining training in heat with “Live High, Train Low” hypoxia (LHTL) further improves thermoregulatory and cardiovascular responses to a heat-tolerance test compared with independent heat training. Methods: A total of 25 trained runners (peak oxygen uptake = 64.1 [8.0] mL·min−1·kg−1) completed 3-wk training in 1 of 3 conditions: (1) heat training combined with “LHTL” hypoxia (H+H; FiO2 = 14.4% [3000 m], 13 h·d−1; train at <600 m, 33°C, 55% relative humidity [RH]), (2) heat training (HOT; live and train <600 m, 33°C, 55% RH), and (3) temperate training (CONT; live and train <600 m, 13°C, 55% RH). Heat adaptations were determined from a 45-min heat-response test (33°C, 55% RH, 65% velocity corresponding to the peak oxygen uptake) at baseline and immediately and 1 and 3 wk postexposure (baseline, post, 1 wkP, and 3 wkP, respectively). Core temperature, heart rate, sweat rate, sodium concentration, plasma volume, and perceptual responses were analyzed using magnitude-based inferences. Results: Submaximal heart rate (effect size [ES] = −0.60 [−0.89; −0.32]) and core temperature (ES = −0.55 [−0.99; −0.10]) were reduced in HOT until 1 wkP. Sweat rate (ES = 0.36 [0.12; 0.59]) and sweat sodium concentration (ES = −0.82 [−1.48; −0.16]) were, respectively, increased and decreased until 3 wkP in HOT. Submaximal heart rate (ES = −0.38 [−0.85; 0.08]) was likely reduced in H+H at 3 wkP, whereas CONT had unclear physiological changes. Perceived exertion and thermal sensation were reduced across all groups. Conclusions: Despite greater physiological stress from combined heat training and “LHTL” hypoxia, thermoregulatory adaptations are limited in comparison with independent heat training. The combined stimuli provide no additional physiological benefit during exercise in hot environments.
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Maunder, Ed, Daniel J. Plews, Fabrice Merien, and Andrew E. Kilding. "Stability of Heart Rate at Physiological Thresholds Between Temperate and Heat Stress Environments in Endurance-Trained Males." International Journal of Sports Physiology and Performance 16, no. 8 (August 1, 2021): 1204–7. http://dx.doi.org/10.1123/ijspp.2020-0351.
Повний текст джерелаАнотація:
Many endurance athletes perform specific blocks of training in hot environments in “heat stress training camps.” It is not known if physiological threshold heart rates measured in temperate conditions are reflective of those under moderate environmental heat stress. A total of 16 endurance-trained cyclists and triathletes performed incremental exercise assessments in 18°C and 35°C (both 60% relative humidity) to determine heart rates at absolute blood lactate and ventilatory thresholds. Heart rate at fixed blood lactate concentrations of 2, 3, and 4 mmol·L−1 and ventilatory thresholds were not significantly different between environments (P > .05), despite significant heat stress-induced reductions in power output of approximately 10% to 17% (P < .05, effect size = 0.65–1.15). The coefficient of variation for heart rate at these blood lactate concentrations (1.4%−2.9%) and ventilatory thresholds (2.3%−2.7%) between conditions was low, with significant strong positive correlations between measurements in the 2 environments (r = .92–.95, P < .05). These data indicate heart rates measured at physiological thresholds in temperate environments are reflective of measurements taken under moderate environmental heat stress. Therefore, endurance athletes embarking on heat stress training camps can use heart rate–based thresholds ascertained in temperate environments to prescribe training under moderate environmental heat stress.
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Saeed, Osama Anwer, Rawaa Turk Abdulghafoor, Sawsan Sabir Al-Salmany, Faris Mahmoud Ali, Anjas Asmara Samsudin, and Elham Khalifa Mahmood. "Effect of temperature on the physiological characteristics of Awassi and crossbred sheep." Journal of Animal Behaviour and Biometeorology 11, no. 4 (November 20, 2023): 2023031. http://dx.doi.org/10.31893/jabb.23031.
Повний текст джерелаАнотація:
This research was carried out to analyze the hematological, biochemical and physiological characteristics correlated with climate temperature in Awassi and crossbred sheep. Two hundred fifty adult Awassi and crossbred sheep (Arabi x Hamadani) were used. Three times weekly, ten times for each breed, vital signs, including heart rate (HR), respiratory rate (RR), rectal temperature (RT), and skin temperature (ST), were recorded. The heat tolerance indices (HT) and the heat tolerance coefficient (HTC) were evaluated. SAS was used to conduct the analyses, which included variance and correlation analyses. Awassi had a significantly higher (P < 0.01) RR than crossbred in the summer under low stress conditions. Awassi HR was significantly lower than that of crossbred sheep, which recorded the highest value in summer. There were no significant differences in RT, HT and HTC between Awassi and crossbred sheep. MCH, MCV, and RDW increased substantially in Awassi sheep exposed to colder winter temperatures. In summer, Awassi's liver enzyme and triglyceride levels significantly decreased, while albumin levels increased. Both HT and HTC had negative correlations with RR. Therefore, it can be concluded that the Awassi breed is equally adapted to the region's hot and arid climate.
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Taofik, A., S. Bandiati, A. M. Maskoen, and M. Yusuf. "The effects of shearing and ascorbyl palmitate administration on physiological and blood metabolite profile of Padjadjaran sheep under heat exposure treatment." Journal of the Indonesian Tropical Animal Agriculture 46, no. 1 (January 18, 2021): 12–19. http://dx.doi.org/10.14710/jitaa.46.1.12-19.
Повний текст джерелаАнотація:
Ascorbyl-6-palmitate (AP) was a lipid-soluble synthetic ester of ascorbic acid that has been used as a preservation agent for foods and as an antioxidant in cosmetics and related products. This study aims to investigate the effect of shearing management and ascorbyl palmitate administration on physiological and hematological profiles in under heat load Padjadjaran sheep. The physiological profile involves respiration rate (RR), Pulse rate (PR), and rectal temperature (RT). Twenty rams Padjadjaran 1 – 1,5 year-old, weighing between 25 to 47.5 kg used from sheep breeding station Purwakarta, West Java - Indonesia. There are two treatments level in this research, (1). Shearing divide into two groups, unshearing (c0) and shearing (c1); (2). AP administration also divides two groups, not given (a0) and given 400 mg each head daily (a1). The whole treatments were a0c0, a0c1, a1c0 and a1c1. Heat exposure application was exposed to sunlight when the sheep exposed, the animal tethered by rope at the neck region. The sheep exposed to the sun when the ambient temperature at least 34oC, 180 minutes each day, three days a week. The result showed that AP administration and shearing have interaction effects on RR, PR and RT. The level of glucose and total protein is affected by interaction effect of AP administration and shearing, while cholesterol affected to shearing. The conclusion, supplementing AP and shearing application could reduce the negative impact of heat stress on physiological and blood metabolite profiles of Padjadjaran sheep. Although the wool of local breed has not economic value, the shearing is regularly needed.
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Shenhe, Liu, Li Jun, Li Zipeng, Deng Tingxian, Zia ur Rehman, Zhou Zichao, and Yang Liguo. "Effect of season and breed on physiological and blood parameters in buffaloes." Journal of Dairy Research 85, no. 2 (May 2018): 181–84. http://dx.doi.org/10.1017/s0022029918000286.
Повний текст джерелаАнотація:
In this Research Communication we describe the effect of temperature and humidity index (THI) on various physiological traits, the plasma heat shock protein 70 (HSP70), heat shock protein 90 (HSP90) and cortisol levels and other blood parameters in crossbred buffalo (Nili-Ravi × Murrah) and Mediterranean buffalo to compare their tolerance to heat stress. As expected, crossbred buffalo had a significantly higher rectal temperature (RT), body surface temperature (BT), respiratory rate (RR), HSP70 and HSP90 levels in summer compared to spring and winter. RT and BT were also significantly higher in spring compared to winter. A significant correlation existed between THI and RT (r = 0·81) and RR (r = 0·84). Importantly, in summer the crossbred buffalo had a significantly lower RT, BT and RR and higher HSP70, HSP90 and cortisol levels than the Mediterranean buffalo. In conclusion, higher THI was associated with significant increase in RT, RR, BT, HSP70, HSP90 and cortisol levels, and the crossbred buffalo were more heat tolerant than Mediterranean buffalo.
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Sun, Xiaonan, Sharadhi Siri, Amirah Hurst, and Hongyu Qiu. "Heat Shock Protein 22 in Physiological and Pathological Hearts: Small Molecule, Large Potentials." Cells 11, no. 1 (December 30, 2021): 114. http://dx.doi.org/10.3390/cells11010114.
Повний текст джерелаАнотація:
Small heat shock protein 22 (HSP22) belongs to the superfamily of heat shock proteins and is predominantly expressed in the heart, brain, skeletal muscle, and different types of cancers. It has been found that HSP22 is involved in variant cellular functions in cardiomyocytes and plays a vital role in cardiac protection against cardiomyocyte injury under diverse stress. This review summarizes the multiple functions of HSP22 in the heart and the underlying molecular mechanisms through modulating gene transcription, post-translational modification, subcellular translocation of its interacting proteins, and protein degradation, facilitating mitochondrial function, cardiac metabolism, autophagy, and ROS production and antiapoptotic effect. We also discuss the association of HSP22 in cardiac pathologies, including human dilated cardiomyopathy, pressure overload-induced heart failure, ischemic heart diseases, and aging-related cardiac metabolism disorder. The collected information would provide insights into the understanding of the HSP22 in heart diseases and lead to discovering the therapeutic targets.
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Dorton, Matthew C., Brent C. Ruby, and Charles L. Dumke. "A synthetic undergarment increases physiological strain." International Journal of Wildland Fire 28, no. 4 (2019): 275. http://dx.doi.org/10.1071/wf18092.
Повний текст джерелаАнотація:
Our aim was to examine the effect of a synthetic material undergarment on heat stress during exercise in a hot environment. Ten active males completed two trials of intermittent (50min walking, 10min sitting) treadmill walking over 3h in 35°C and 30% relative humidity. Subjects wore wildland firefighter flame-resistant meta-aramid blend pants and shirt with either a 100% cotton (C) or flame-retardant modacrylic undergarment (S), while carrying a 16-kg pack, helmet and leather gloves. Exercise was followed by a 30-min rest period without pack, helmet, gloves, and outerwear shirt. Rectal temperature and physiological strain were greater in S than C (P=0.04). No significant differences were found for heart rate, rating of perceived exertion, energy expenditure or skin temperature between C and S. Skin blood flow increased significantly in S following the second hour of exercise, resulting in a time×trial interaction (P=0.001). No significant differences for skin blood flow were found post exercise. Sweat rate and percent dehydration were not different between C and S. These data indicate that, of the two undergarments investigated, the synthetic undergarment negatively affected physiological factors that have been shown to indicate an increased risk of heat-related injuries.
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Rio-Aviles, Andrea Dahnae del, Abelardo Correa-Calderon, Leonel Avendaño-Reyes, Milton G. Thomas, R. Mark Enns, Scott E. Speidel, Miguel Angel Sanchez-Castro, Ricardo Zamorano-Algandar, and Pablo Luna-Nevárez. "PSXI-1 Effects of mineral supplementation during summer on physiological variables and milk production in Holstein dairy cows." Journal of Animal Science 97, Supplement_3 (December 2019): 389. http://dx.doi.org/10.1093/jas/skz258.775.
Повний текст джерелаАнотація:
Abstract Summer season in northwest Mexico is characterized by hot-humid weather conditions that lead to heat stress and affect physiological and productive performance of lactating Holstein cows. Mineral supplementation has been proposed as strategy to alleviate negative effects of heat stress in dairy cattle. Thus, the objective of this study was to evaluate the effect of an injectable mineral supplement on physiological variables and milk production in Holstein cows managed during summer. Sixteen cows were randomly assigned to 1 of 2 experimental groups: Mineral-treated (TRT; n = 8) or control (CON; n = 8). The TRT group received 3 injections of Fosfosan® (10 ml, i.m., Virbac, Uruguay), on days 0, 7 and 17, considering summer onset as day 0 (June 21st), whereas group CON was untreated. Physiological variables such as respiratory rate (RR), vaginal temperature (VT) and skin-surface temperature (SST), were registered twice a week (0500-1700 h) during 6 weeks. Ambient temperature and humidity were collected to calculate the daily temperature and humidity index (THI). Data were analyzed using a mixed model with repeated measures, which included fixed effects of treatment, time and treatment*time, and sire as random effect. According to the THI, Holstein cows were exposed to heat stress during the experiment (>72 units). Cows in the TRT group showed higher (P < 0.05) milk production than CON cows (17.93±0.47 vs 17.02±0.51 kg/day) and lower (P < 0.01) VT (39.14±0.11 vs 39.46±0.15 °C). Relative to CON cows, treated cows also had lower RR (63.16±0.65 vs 64.47±0.76 breaths/min) and lower SST (33.75±0.15 vs 34.02±0.16 °C). All physiological variables showed a significant effect of time (P < 0.01). In conclusion, mineral supplementation during summer appears to improve physiological and productive performance in heat-stressed milking dairy cows; therefore, we suggest to consider this management as strategy to reduce negative effects of summer and heat stress on the dairy industry in northwest Mexico.
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Gallant, Melanie J., Sacha LeBlanc, Tyson J. MacCormack, and Suzanne Currie. "Physiological responses to a short-term, environmentally realistic, acute heat stress in Atlantic salmon, Salmo salar." FACETS 2, no. 1 (May 1, 2017): 330–41. http://dx.doi.org/10.1139/facets-2016-0053.
Повний текст джерелаАнотація:
Atlantic salmon populations are declining, and warming river temperatures in the summer months are thought to be a significant contributing factor. We describe the time course of cellular and metabolic responses to an ecologically relevant short-term thermal cycle in juvenile Atlantic salmon. We then examined whether this heat event would affect tolerance to a subsequent heat shock in terms of critical thermal maximum (CTmax). Fish induced heat shock protein 70 in red blood cells, heart, liver, and red and white muscle; whole blood glucose and lactate transiently increased during the heat cycle. In contrast, we observed no significant effect of a prior heat shock on CTmax. The CTmax was positively correlated with Fulton’s condition factor suggesting that fish with greater energy reserves are more thermally tolerant. Atlantic salmon activate cellular protection pathways in response to a single thermal cycle and appear to cope with this short-term, ∼1 d heat shock, but this challenge may compromise the ability to cope with subsequent heat events.
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Herbut, Piotr, Sabina Angrecka, Dorota Godyń, and Gundula Hoffmann. "The Physiological and Productivity Effects of Heat Stress in Cattle – A Review." Annals of Animal Science 19, no. 3 (July 1, 2019): 579–93. http://dx.doi.org/10.2478/aoas-2019-0011.
Повний текст джерелаАнотація:
AbstractA trend of global warming has been observed over the last few years and it has often been discussed whether there is an effect on livestock. Numerous studies have been published about heat stress in cattle and its influence on the physiology and productivity of animals. Preventing the negative effects of heat stress on cattle is essential to ensure animal welfare, health and productivity. Monitoring and analysis of physiological parameters lead to a better understanding of the adaptation processes. This can help to determine the risk of climate change and its effects on performance characteristics, e.g. milk yield and reproduction. This, in turn, makes it possible to develop effective measures to mitigate the impact of heat load on animals. The aim of this article is to provide an overview of the current literature. Studies especially about the physiological and productive changes due to heat stress in cattle have been summarised in this review. The direction of future research into the aspect of heat stress in cattle is also indicated.
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Losnegard, Thomas, Martin Andersen, Matt Spencer, and Jostein Hallén. "Effects of Active Versus Passive Recovery in Sprint Cross-Country Skiing." International Journal of Sports Physiology and Performance 10, no. 5 (July 2015): 630–35. http://dx.doi.org/10.1123/ijspp.2014-0218.
Повний текст джерелаАнотація:
Purpose:To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing.Methods:Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods.Results:The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol.Conclusions:Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.
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Vesic, Zoran, Milica Vukasinovic-Vesic, Dragan Dincic, Maja Surbatovic, and Sonja Radakovic. "The effects of acclimatization on blood clotting parameters in exertional heat stress." Vojnosanitetski pregled 70, no. 7 (2013): 670–74. http://dx.doi.org/10.2298/vsp120630013v.
Повний текст джерелаАнотація:
Background/Aim. Exertional heat stress is a common problem in military services. Considering the coagulation abnormalities are of major importance in development of severe heat stroke, we wanted to examine changes in hemostatic parameters in soldiers during exertional heat stress test as well as the effects of a 10-day passive or active acclimatization in a climatic chamber. Methods. A total of 40 male soldiers with high aerobic capacity performed exertional heat stress test (EHST) either in cool [20?C, 16?C wet bulb globe temperature (WBGT)], or hot (40?C, 29?C, (WBGT) environment, unacclimatized (U) or after 10 days of passive (P) or active (A) acclimatization. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Platelet count (PC), antithrombin III (AT), and prothrombin time (PT) were assessed in blood samples collected before and immediately after the EHST. Results. EHST in hot conditions induced physiological heat stress (increase in Tty and HR), with a significant increase in prothrombin time in the groups U and A. Platelet counts were significantly higher after the EHST compared to the basic levels in all the investigated groups, regardless environmental conditions and acclimatization state. Antithrombin levels were not affected by EHST whatsoever. Conclusion. In the trained soldiers, physiological heat stress caused mild changes in some serum parameters of blood clotting such as prothrombin time, while others such as antithrombin levels were not affected. Platelet counts were increased after EHST in all groups. A 10-day passive or active acclimatization in climatic chamber showed no effect on parameters investigated.
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Nandraziova, L., K. Matasova, and R. Gumulak. "Phototherapy and its effect on some physiological functions in newborns." Acta Medica Martiniana 18, no. 1 (June 1, 2018): 5–13. http://dx.doi.org/10.2478/acm-2018-0001.
Повний текст джерелаАнотація:
Abstract Phototherapy represents the most common therapeutic intervention at neonatology departments in the first days of life. The beneficial effects of light on the decrease of the serum bilirubin level were first described by Cremer et al. in 1950’s (1). Since then phototherapy has been successfully used to treat severe hyperbilirubinaemia and has almost completely replaced exchange transfusion. Phototherapy is a relatively non-invasive method. However, along with decreasing bilirubin level, it can also influence some other functions: perfusion of organs, predominantly skin; peripheral vascular resistance; distribution of blood flow; heart activity and, thus, also systemic blood pressure along with breathing. A side component of applied light is a certain amount of heat which warms the body surface up and, therefore, the risk of exogenous overheating and increased water loss through the skin arise. Maternal-infant separation, modification of calcium homeostasis, disturbed circadian rhythm, or changes of the hemodynamics of various organ systems are only a few of the undesired effects which prove phototherapy not to be a treatment without any side effects. Careful indication of phototherapy is essential, particularly in premature infants.
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Luitel, Kabita, Dil Bahadur Gurung, Harihar Khanal, and Kedar Nath Uprety. "Numerical Study of Transient Bio-Heat Transfer Model With Heat Transfer Coefficient and Conduction Effect in Cylindrical Living Tissue." Nepali Mathematical Sciences Report 36, no. 1-2 (December 31, 2019): 17–26. http://dx.doi.org/10.3126/nmsr.v36i1-2.29967.
Повний текст джерелаАнотація:
The human thermal comfort is affected by the body’s heat exchange mechanism conduction, convection, radiation, and evaporation. The mode of heat transfer between the body and environment depends upon the human internal physiological phenomena, together with the boundary conditions. The present paper provides the comprehensive overview of the thermoregulatory system of human body and studies the numerical solution of unsteady-state one dimensional Pennes bio-heat equation with appropriate boundary conditions. The solution is used to observe the temperature profiles at different thermal conductivities, and different heat transfer coefficients in the living tissue at the various time steps. Various physical and physiological factors across the cylindrical living tissue have been incorporated in the model.
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Tian, Zipeng, Bingru Huang, and Faith C. Belanger. "Effects of Epichloë festucae Fungal Endophyte Infection on Drought and Heat Stress Responses of Strong Creeping Red Fescue." Journal of the American Society for Horticultural Science 140, no. 3 (May 2015): 257–64. http://dx.doi.org/10.21273/jashs.140.3.257.
Повний текст джерелаАнотація:
Strong creeping red fescue (Festuca rubra ssp. rubra) is an important cool season turfgrass species. Cultivars are often infected with the fungal endophyte Epichloë festucae. Endophyte infection is known to confer insect and disease resistance to the plants. The effect of endophyte infection on drought or heat stress tolerance of strong creeping red fescue is not yet established. The objectives of this controlled-environment study were to determine if endophyte infection had any effect on physiological parameters associated with plant tolerance to drought or heat stress or the combination of the two stresses. In this study, endophyte status had no effect on turf quality (TQ), relative water content (RWC), photochemical efficiency, chlorophyll content, electrolyte leakage (EL), or malondialdehyde (MDA) content of the plants under any of the stress treatments. Our results suggested that E. festucae infection had no physiological effects on improving drought, heat or the combined stress tolerance in strong creeping red fescue.
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Rusdaniaji, Danarwan, and Rini Dharmastiti. "Effect of Wearing Different Types of Face Mask to Heat Strain During Physical Activities." Jurnal Sistem Teknik Industri 23, no. 2 (July 28, 2021): 178–89. http://dx.doi.org/10.32734/jsti.v23i2.6392.
Повний текст джерелаАнотація:
There is a concern to use masks during physical activities when exercising and working. Wearing masks during physical activity will pose a risk to physiological changes in the body and human heat strain by the principle of a mask can block the respiratory tract. This study aims to determine how much the human physiological changes quantitatively and qualitatively when using different types of medical masks, cloths and N95. There were 10 respondents as a sample of this study. The results obtained show that the different types of masks to the physiological response of the human body, cloth masks can affect the physiological changes the highest compared to medical masks and N95. The subjective response in the form of thermal comfort, mask sensation, and thermal sensation shows that of the 3 types of masks, the N95 mask is the mask that is the most uncomfortable when worn. The recommendations of the 3 types of masks are medical masks because they affect the slightest increase in the risk of heat stress while the cloth masks have the highest increase in tympanic temperature and Physiological Strain Index.
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Setiawan, Arif Adham, Erwanto Erwanto, Madi Hartono, and Arif Qisthon. "PENGARUH MANIPULASI IKLIM KANDANG MELALUI PENGKABUTAN TERHADAP RESPON FISIOLOGIS DAN KETAHANAN PANAS KAMBING SAPERA DAN PERANAKAN ETTAWA." Jurnal Riset dan Inovasi Peternakan (Journal of Research and Innovation of Animals) 5, no. 1 (April 1, 2021): 64–69. http://dx.doi.org/10.23960/jrip.2021.5.1.64-69.
Повний текст джерелаАнотація:
This study aimed to determine the effect of cage microclimate manipulation with misting on physiological responses and heat resistance of goats (Sapera and Ettawa Grade). This research was conducted in April - May 2020 at Telaga Rizki People's Farm, Metro City, Lampung Province. This study used an experimental method, Split Plot design with a completely randomized design (CRD). This study used two treatments, namely modification of the pen consisting of pens without misting (K0) and pens with misting (K1) and two breed of goats, namely Sapera and Ettawa Grade (PE) goats. Each treatment was carried out 3 times. Goats as subplots and microclimate modification of the pen as the main plot. In this study, twelve female goats were used, namely 6 Sapera goats and 6 Ettawa Grade (PE) goats aged 2-3 years. The parameters observed were microclimate condition, namely air temperature, relative humidity (RH), and Temperature Humidity Index (THI), and physiological responses including rectal temperature, respiration frequency, heart rate frequency, and heat tolerance (HTC). The results of the research showed that there was significant effect (P<0.05) of treatments on RH and THI. The resilts also showed that there was no significant effect (P>0.05) of treatments on rectal temperature, heart rate, respiration frequency, HTC and environment temperature.
Keywords : Misting, Pens microclimate, Physiological responses
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SINGH, V. P., SHIVANI NAGAR, NEERA SINGH, RAJKUMAR DHAKAR, and AJAY ARORA. "Effect of endogenous gibberellic acid content on physiological and yield related traits in late sown wheat." Indian Journal of Agricultural Sciences 92, no. 6 (January 6, 2022): 700–704. http://dx.doi.org/10.56093/ijas.v92i6.102508.
Повний текст джерелаАнотація:
Terminal heat stress is becoming major factors in limiting wheat production with increasing evidence of heat stress in present scenario of climate change. Plant hormones are key player in determining plant response to these stresses from perception of stress to final adoptive response. Gibberellic acid is one of the major plant hormone playing crucial role in plant development from germination to seed development, but there is huge gap in knowledge about its role under heat stress. Present study was conducted in late sown wheat (i.e. on 5th January)to examine the inter-relationship between leaf gibberellic acid (GA3) level at reproductive stage with physiological and yield related traits under heat stress in 40 wheat genotypes. Genotypes were categorized into three classes namely tolerant, intermediate and sensitive based on heat stress tolerance ability for further analysis. The diversity in endogenous GA3 concentration was found among the cultivars. The unique inverse relationship between GA3 level in flag leaf and tolerance level of genotypes was found in this study through regression analysis (p<0.05). The path analysis showed that GA3 had direct negative influence on test weight under heat stress conditions. Thus, investigations of mechanism of GA3 influence on sink capacity have the potential to develop heat tolerant genotype and increase wheat production under heat stress.
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Leicht, Anthony S., Aaron Halliday, Wade H. Sinclair, Shaun D’Auria, Martin Buchheit, Glen P. Kenny, and Jamie Stanley. "Heart rate variability responses to acute and repeated postexercise sauna in trained cyclists." Applied Physiology, Nutrition, and Metabolism 43, no. 7 (July 2018): 704–10. http://dx.doi.org/10.1139/apnm-2017-0581.
Повний текст джерелаАнотація:
Short- to medium-term (i.e., 4–14 days) heating protocols induce physiological adaptations including improved cardiac autonomic modulations, as assessed using heart rate variability, which may contribute to greater exercise performance. Whether similar cardiac autonomic changes occur during an intense heating protocol (sauna) reported to increase plasma volume in athletes remains to be confirmed. This study examined changes in heart rate and its variability during a single extreme heat (sauna) exposure and repeated exposures in athletes. Six well-trained male cyclists undertook sauna bathing (30 min, 87 °C, 11% relative humidity) immediately after normal training over 10 consecutive days. Heart rate recordings were obtained during each sauna bout. Heart rate and its variability (natural logarithm of root mean square of successive differences, lnRMSSD) were analysed during 10-min periods within the first bout, and changes in heart rate and lnRMSSD were analysed during each bout via magnitude-based inferences. During the first sauna bout, heart rate was almost certainly increased (∼32%, effect size 1.68) and lnRMSSD was almost certainly reduced (∼62%, effect size –5.21) from the first to the last 10-min period, indicating reduced parasympathetic and (or) enhanced sympathetic modulations. Acute exposure to extreme heat stress via sauna produced alterations in heart rate and cardiac autonomic modulations with successive postexercise heat exposures producing unclear changes over a 10-day period. The physiological benefits of intense heating via sauna on cardiac control in athletes remain to be elucidated.
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Rajametov, Sherzod Nigmatullaevich, Eun Young Yang, Hyo Bong Jeong, Myeong Cheoul Cho, Soo Young Chae, and Niroj Paudel. "Heat Treatment in Two Tomato Cultivars: A Study of the Effect on Physiological and Growth Recovery." Horticulturae 7, no. 5 (May 20, 2021): 119. http://dx.doi.org/10.3390/horticulturae7050119.
Повний текст джерелаАнотація:
High temperature (HT) significantly affects crop physiological traits and reduces productivity in plants. To increase yields as well as survival of crops under HT, developing heat-tolerant plants is one of the main targets in crop breeding programs. The present study attempted to investigate the linkage of the heat tolerance between the seedling and reproductive growth stages of tomato cultivars ’Dafnis‘ and ’Minichal.’ This research was undertaken to evaluate heat tolerance under two experimental designs such as screening at seedling stage and screening from reproductive traits in greenhouses. Survival rate and physiological responses in seedlings of tomatoes with 4-5 true leaves were estimated under HT (40 °C, RH 70%, day/night, respectively) and under two control and HT greenhouse conditions (day time 28 °C and 40 °C, respectively). Heat stress significantly affected physiological–chemical (photosynthesis, electrolyte conductivity, proline) and vegetative parameters (plant height, shoot fresh weight, root fresh weight) in all tomato seedlings. The findings revealed that regardless of tomato cultivars the photosynthesis, chlorophyll, total proline and electrical conductivity parameters were varied in seedlings during the heat stress period. The heat tolerance rate of tomatoes in the seedling stage might not always be associated with reproductive parameters. HT reduced fruit parameters such as fruit weight (31.9%), fruit length (14.1%), fruit diameter (19.1%), and fruit hardness (9.1%) compared to NT under HT in heat-susceptible tomato cultivar ‘Dafnis’, while in heat-tolerant cultivar ‘Minichal’ fruit length (7.1%) and fruit diameter (12.1%) was decreased by the effects of HT, but on the contrary fruit weight (3.6%) and fruit hardness (8.3%) were increased. In conclusion, screening and selection for tomatoes should be evaluated at the vegetative and reproductive stages with consideration of reproductive parameters.
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TIAN, Xue-Jun, Hong-Zheng TAO, Jing LUO, Xu-Dong ZHANG, and Fa-Qing TAO. "Physiological Effect of Heat Stress on Pea (Pisum sativum) Hypocotyls." Acta Botanica Yunnanica 31, no. 4 (March 30, 2010): 363–68. http://dx.doi.org/10.3724/sp.j.1143.2009.09017.
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Gudev, D., S. Popova-Ralcheva, P. Moneva, Y. Aleksiev, T. Peeva, Y. Ilieva, and P. Penchev. "Effect of heat-stress on some physiological and biochemical parameters in buffaloes." Italian Journal of Animal Science 6, sup2 (January 2007): 1325–28. http://dx.doi.org/10.4081/ijas.2007.s2.1325.
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Soltan, M. E., A. A. Enab, and A. A. El-Fiky. "EFFECT OF COLD AND HEAT STRESSES ON SOME PHYSIOLOGICAL TRAITS IN CHICKENS." Menoufia Journal of Animal Poultry and Fish Production 1, no. 2 (August 1, 2017): 25–26. http://dx.doi.org/10.21608/mjapfp.2017.176258.
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Soltan, M. E., A. A. Enab, and A. A. El Fiky. "EFFECT OF COLD AND HEAT STRESSES ON SOME PHYSIOLOGICAL TRAITS IN CHICKENS." Menoufia Journal of Animal Poultry and Fish Production 1, no. 2 (August 1, 2017): 25–26. http://dx.doi.org/10.21608/mjapfp.2017.126163.
Повний текст джерела
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Petersen, Carl J., Marc R. Portus, David B. Pyne, Brian T. Dawson, Matthew N. Cramer, and Aaron D. Kellett. "Partial Heat Acclimation in Cricketers Using a 4-Day High Intensity Cycling Protocol." International Journal of Sports Physiology and Performance 5, no. 4 (December 2010): 535–45. http://dx.doi.org/10.1123/ijspp.5.4.535.
Повний текст джерелаАнотація:
Cricketers are often required to play in hot/humid environments with little time for heat adaptation.Purpose:We examined the effect of a short 4-d hot/humid acclimation program on classical physiological indicators of heat acclimation.Methods:Male club cricketers were randomly assigned into heat acclimation (ACC, n = 6) or control (CON, n = 6) groups, and 30 min treadmill trials (10 km/h, approx. 30 ± 1.0°C, approx. 65 ± 6% RH) were conducted at baseline and postacclimation. The ACC group completed four high intensity (30–45 min) acclimation sessions on consecutive days at approx. 30°C and approx. 60% RH using a cycle ergometer. The CON group completed matched cycle training in moderate conditions (approx. 20°C, approx. 60% RH). Physiological measures during each treadmill trial included heart rate; core and skin temperatures; sweat Na+, K+ and Cl– electrolyte concentrations; and sweat rate.Results:After the 4-d intervention, the ACC group had a moderate decrease of -11 (3 to -24 beats/min; mean and 90% CI) in the 30 min heart rate, and moderate to large reductions in electrolyte concentrations: Na+ -18% (–4 to -31%), K+ -15% (0 to -27%), Cl– -22% (-9 to -33%). Both ACC and CON groups had only trivial changes in core and skin temperatures and sweat rate. After the intervention, both groups perceived they were more comfortable exercising in the heat. The 4-d heat intervention had no detrimental effect on performance.Conclusions:Four 30–45 min high intensity cycle sessions in hot/humid conditions elicited partial heat acclimation. For full heat acclimation a more intensive and extensive (and modality-specific) acclimation intervention is needed for cricket players.
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Cheuvront, Samuel N., Brett R. Ely, Robert W. Kenefick, Bozena B. Michniak-Kohn, Jennifer C. Rood, and Michael N. Sawka. "No effect of nutritional adenosine receptor antagonists on exercise performance in the heat." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 296, no. 2 (February 2009): R394—R401. http://dx.doi.org/10.1152/ajpregu.90812.2008.
Повний текст джерелаАнотація:
Nutritional adenosine receptor antagonists can enhance endurance exercise performance in temperate environments, but their efficacy during heat stress is not well understood. This double-blinded, placebo-controlled study compared the effects of an acute dose of caffeine or quercetin on endurance exercise performance during compensable heat stress (40°C, 20–30% rh). On each of three occasions, 10 healthy men each performed 30-min of cycle ergometry at 50% V̇o2peak followed by a 15-min performance time trial after receiving either placebo ( Group P), caffeine ( Group C; 9 mg/kg), or quercetin ( Group Q; 2,000 mg). Serial blood samples, physiological (heart rate, rectal, and mean skin body temperatures), perceptual (ratings of perceived exertion, pain, thermal comfort, motivation), and exercise performance measures (total work and pacing strategy) were made. Supplementation with caffeine and quercetin increased preexercise blood concentrations of caffeine (55.62 ± 4.77 μM) and quercetin (4.76 ± 2.56 μM) above their in vitro inhibition constants for adenosine receptors. No treatment effects were observed for any physiological or perceptual measures, with the exception of elevated rectal body temperatures (0.20–0.30°C; P < 0.05) for Group C vs. Groups Q and P. Supplementation did not affect total work performed ( Groups P: 153.5 ± 28.3, C: 157.3 ± 28.9, and Q: 151.1 ± 31.6 kJ; P > 0.05) or the self-selected pacing strategy employed. These findings indicate that the nutritional adenosine receptor antagonists caffeine and quercetin do not enhance endurance exercise performance during compensable heat stress.
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GULAB SINGH YADAV, SUBHASH BABU, ANUP DAS, B.K. KANDPAL, SANJEEV KUMAR, DHIMAN DAS CHOUDHURY, and K.K. BARMAN. "Effect of different microenvironment on heat unit requirement and heat use efficiency of different lentil genotypes sown in rice fallow condition." Indian Journal of Agronomy 66, no. 4 (October 10, 2001): 393–99. http://dx.doi.org/10.59797/ija.v66i4.2882.
Повний текст джерелаАнотація:
To utilize the rice (Oryza sativa L.) fallow land of the northeastern region (NER) of India and enhance the crop- ping intensity, a set of lentil (Lens culinaris) genotypes/varieties were evaluated for heat requirement and use effi- ciency under 2 thermal regimes in Tripura [altitude of 52 m ASL (meter above sea level)] during 201415 and 2015-16 (November to March). The experiment consisted of 14 lentil genotypes namely HUL 57, L 4076, ILL 10897, ILL 10893, BM 6, BM 7, WBL 77, Subrata, ILL-6002, L-1111-12, L-1112-18, L-1112-20, ILL- 10951, and L 1112-07 which were sown under two thermal regimes e.g., 16th November (1st date of sowing) and 1st December (2nd date of sowing) during both the years. Results revealed that crop sown on 16th November took 3 days more than that of 1st December sowing to attain physiological maturity. Lentil L-1112-18 took a minimum number of days (80) to reach physiological maturity stage followed by L-1111-12 (82 days). Crop sown on 1st De- cember consumed more growing degree days (GDD) between different phenological stages, for example sowing to 50% emergence (113.8), 1st flower bud initiation to 50% flowering (250.4), and 50% flowering to physiological maturity (632.3) except for 50% emergence to 1st flower bud initiation (682.4) than that of 16th November sowing. Lentil variety HUL 57 required the highest GDD between all the phenological stages. Accumulated GDD and heliothermal unit (HTU) were higher for 16th Nov sowing ranged from 100.4 C days (emergence) to 1719.5 C days (physiological maturity) and accumulated HTU from 127.6 C day hours (emergence) to 2199.2 C day hours (physiological maturity) than 1st December sowing. HUL 57 accumulated the highest GDD and HTU from sowing to physiological maturity. The pheno-thermal index (PTI) was higher between sowing to 50% emergence (20.2-21.8) and 50% flowering to physiological maturity (18.2-20.1) than in between of 1st flower bud initiation to 50% flowering (16.2-17.4) and 50% emergence to 1st flower bud initiation (16.5-17.9). Lentil HUL 57 had the highest PTI (21.3) followed by L-4076 (21.0) while the lowest PTI was by BM 6 (16.1) followed by L-1112-18 (17.1) between 50% flowering to physiological maturity. Lentil sown on 16th Nov produced more seed (1008.9 kg/ha), straw (1608.9 kg/ ha), and biomass (2617.6 kg/ha) yields, and improved heat use efficiency for grain yield (0.60 kg/ha C day-1) and biomass yield (1.56 kg/ha C day-1) than that of sowing on 1st Dec. Lentil genotype BM-6 produced maximum seed yield (1270 kg/ha) followed by WBL 77 (1234 kg/ha) and L-1112-18 (1231.5 kg/ha). The highest straw yield was produced by WBL 77 (1747.5 kg/ha) followed by L-4076 (1715.5 kg/ha) and L-1112-18 (1685.5 kg/ha). However, genotype L-1112-18 produced maximum biomass yield (2917 kg/ha) followed by L-1111-12 (2894.5 kg/ha) and L- 4076 (2883 kg/ha). The genotype L-1112-18 had maximum heat use efficiency for seed yield (0.90 kg/ha C day-1) and biomass yield (2.12 kg/ha C day-1). Thus, the study recommended the genotypes BM-6, WBL 77, and L-1112- 18 which are heat efficient and high yielding for efficient utilization of rice fallow areas under both the thermal re- gimes.
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Gómez Guzmán, Javier Alejandro, José Fernando Vázquez Armijo, Ana Laura Lara Rivera, Juan Gabriel Magaña Monforte, Juan Carlos Martínez Gonnzález, and Gaspar Manuel Parra-Bracamonte. "Physiological response of Katahdin ewes to the absence of shadows in tropical region of Mexico." Journal of Animal Behaviour and Biometeorology 12, no. 1 (February 5, 2024): 2024005. http://dx.doi.org/10.31893/jabb.2024005.
Повний текст джерелаАнотація:
This study evaluated the effect of environmental conditions on the physiological and body infrared temperature traits of Katahdin sheep. Ten recently reproductive-managed ewes were randomly segregated into two groups. The control group (CG) was under outdoor conditions with shadow access, and the experimental group (EG) was under outdoor conditions without shadow access. Traits were measured for 16 days, and the environmental traits confirmed significant differences between groups, with an average temperature-humidity index (THI) of 68.64±1.46 for the CG and 72.98±3.17 for the EG, with a breach of five units between groups. The THI was subsequently used to evaluate the heat load. Respiratory frequency was the physiological variable that responded the most to heat stress. The rectal temperature of the sheep was greater in the experimental group than in the control group, indicating an increase in heat stress. The EG also presented higher heat emissions from body regions, which was associated with changes in core body temperature and blood flow at the body surface. Differences in hematological parameters, such as the erythrocyte count, mean corpuscular volume, and total plasma protein concentration, were found between the groups. Infrared thermography was found to be efficient for estimating heat stress in sheep species, and head temperature was found to be a reliable indicator of physiological thermal stress.
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Sidhu, Pardeep, Henry T. Peng, Bob Cheung, and Andrea Edginton. "Simulation of differential drug pharmacokinetics under heat and exercise stress using a physiologically based pharmacokinetic modeling approach." Canadian Journal of Physiology and Pharmacology 89, no. 5 (May 2011): 365–82. http://dx.doi.org/10.1139/y11-030.
Повний текст джерелаАнотація:
Under extreme conditions of heat exposure and exercise stress, the human body undergoes major physiological changes. Perturbations in organ blood flows, gastrointestinal properties, and vascular physiology may impact the body’s ability to absorb, distribute, and eliminate drugs. Clinical studies on the effect of these stressors on drug pharmacokinetics demonstrate that the likelihood of pharmacokinetic alteration is dependent on drug properties and the intensity of the stressor. The objectives of this study were to use literature data to quantify the correlation between exercise and heat exposure intensity to changing physiological parameters and further, to use this information for the parameterization of a whole-body, physiologically based pharmacokinetic model for the purposes of determining those drug properties most likely to demonstrate altered drug pharmacokinetics under stress. Cardiac output and most organ blood flows were correlated with heart rate using regression analysis. Other altered parameters included hematocrit and intravascular albumin concentration. Pharmacokinetic simulations of intravenous and oral administration of hypothetical drugs with either a low or high value of lipophilicity, unbound fraction in plasma, and unbound intrinsic hepatic clearance demonstrated that the area under the curve of those drugs with a high unbound intrinsic clearance was most affected (up to a 130% increase) following intravenous administration, whereas following oral administration, pharmacokinetic changes were smaller (<40% increase in area under the curve) for all hypothetical compounds. A midazolam physiologically based pharmacokinetic model was also used to demonstrate that simulated changes in pharmacokinetic parameters under exercise and heat stress were generally consistent with those reported in the literature.
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Yadav, Satender, Vikram Singh, Hari Kesh, Anu Naruka, Mukesh Kumar, Virender Singh Mor, and Shikha Yashveer. "Morpho-physiological characterization and selection of heat tolerant wheat lines using selection indices." Electronic Journal of Plant Breeding 15, no. 2 (July 9, 2024): 347–55. http://dx.doi.org/10.37992/2024.1502.056.
Повний текст джерелаАнотація:
Heat stress is one of the major constraints in wheat production due to its adverse effect on grain yield and component traits. Moreover, it negatively affects the physiological, biochemical and quality traits of wheat. Therefore, selection of heat tolerant wheat lines is one of the major breeding goals for wheat scientist. In present study, 238 recombinant inbred lines were evaluated along with their parents WH 711 × WH 542 under timely and late sown (heat stress) condition. The heat tolerance indices were calculated based on grain yield under normal and stress conditions. The mean grain yield of 238 wheat lines was reduced by 20.54% suggesting critical effect of heat stress on grain yield. The harmonic mean (HM), stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), and mean relative performance (MRP) were correlated significantly and positively with grain yield under stress and normal conditions. Whereas, Tolerance index (TOL) was correlated negatively with grain yield under stress conditions and positively under normal condition. Based on STI, MP, HM, GMP and MRP, wheat lines WL 92, WL 119, WL 114, WL 110, WL 6 were identified as heat tolerant and could be utilized as potential lines for increasing heat stress tolerance of future wheat breeding programs.
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Pehlivan, Erkan, Mahmut Kaliber, Yusuf Konca, and Gürsel Dellal. "Effect of shearing on some physiological and hormonal parameters in Akkaraman sheep." Asian-Australasian Journal of Animal Sciences 33, no. 5 (May 1, 2020): 848–55. http://dx.doi.org/10.5713/ajas.19.0400.
Повний текст джерелаАнотація:
Objective: Shearing is one of the practices that is applied periodically to fiber producing animals, which can also alter resistance of animals to high temperatures in especially summer months. This study aimed to investigate effects of shearing on some physiological and hormonal parameters in Akkaraman sheep during summer season.Methods: This study was carried out on 39 non-pregnant Akkaraman ewes (aged 1.5 years at the beginning of experiment). The 39 ewes were chosen randomly from the flock belonging to the Erciyes University and they were assigned to two groups as follows: i) group A (n = 20) designed as the control group, they were shorn and group B (n = 19) designed as the experimental group, they were unshorn. Prior to the shearing (–1 day) and on days 1, 7, 15, 30, 45, 60, 75, and 90 following the shearing, blood samples were taken from the vena jugularis of each sheep. Cortisol, β-endorphin, growth hormone (GH), thyroxine (T4), triiodothyronine (T3), and heat shock protein 70 (HSP-70) concentrations were determined using the enzyme immunoassay method. Body weight (BW), rectal temperature (RT), pulse rate (PR), and respiratory rate (RR) of each sheep were recorded at the same time. The data obtained were analyzed using two-way repeated measures analysis of variance.Results: Statistical analysis showed a significant effect of shearing×period interaction (p<0.01) and a significant effect of period (p<0.01) on BW, HSP-70, cortisol, T4 and RT, PR, GH, β-endorphin, T3, respectively. Also these analysis showed no significant effect of shearing× period interaction or period on RR.Conclusion: The results showed that the thermoregulation abilities of sheep were affected by shearing treatment and the shorn ewes were less affected by heat stress. In conclusion, based on the data of this study, shearing can be considered as a necessary management practice that requires protection for sheep from the effect of heat stress.
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Valente, Ériton Egidio Lisboa, Mario Luiz Chizzotti, Cristiane Viol Ribeiro de Oliveira, Matheus Castilho Galvão, Silas Sebastião Domingues, Aline De Castro Rodrigues, and Marcio Machado Ladeira. "Intake, physiological parameters and behavior of Angus and Nellore bulls subjected to heat stress." Semina: Ciências Agrárias 36, no. 6Supl2 (December 16, 2015): 4565. http://dx.doi.org/10.5433/1679-0359.2015v36n6sup2p4565.
Повний текст джерелаАнотація:
Genetics differences between breeds may determine the tolerance to high temperature, effect dry matter intake and consequently cattle performance. The effect of temperature and humidity index (THI) on diurnal, nocturnal and daily intake, water intake, physiologic parameters and behavior of Nellore (B. indicus) and Angus (B. taurus) bulls were evaluated. Eight Angus and eight Nellore young bulls (337±7.4 kg and 16 months of age) were allocated in two climate-controlled rooms for 32 days. In the period 1, all bulls were housed in thermoneutral conditions (TN, THI = 72.6) for 10 days. In period 2 (10 days), four Angus and four Nellore bulls were subjected to low heat stress (LHS, THI = 76.4) in daytime, and four Angus and four Nellore bulls were subjected to high heat stress (HHS, THI = 81.5) in daytime. The diurnal and daily dry matter intake (DMI) of Nellore were not affected (P>0.05) by heat stress. However, Angus bulls decreased diurnal DMI by 24% and daily DMI decreased (P<0.05) by 15% on HHS. In TN Angus bulls had higher (P<0.05) daily DMI (36.2 g/kg of BW) than Nellore (29.1 g/kg of BW), but in HHS they had similar (P>0.05) daily DMI (31.6 and 30.2 g/kg of BW, respectively). We observed an increase (P<0.05) in respiratory frequency, but water intake was not affected (P>0.05) by heat stress. The heart rate decreased (P<0.05) with heat stress. No differences were found (P>0.05) in feeding behavior. Therefore, THI stress threshold should distinct for Angus and Nellore bulls. The use of feed intake information may improve the prediction of thermic discomfort on specific climate condition.