Effect Of High Environmental Temperature Research Articles

Assessing responses to heat in a range-shifting, nocturnal, flying squirrel

Abstract Over the last few decades North American flying squirrels (Glaucomys spp.) have experienced dramatic northward range shifts. Previous studies have focused on the potential effects of warming winter temperatures, yet the hypothesis that rising summer temperature had a role in these range shifts remained unexplored. We therefore sought to determine the effect of high environmental temperatures on the thermoregulation and energetics of flying squirrels in an area of the Northeast of North America with a recent species turnover. Unable to find a logistically feasible population of the northern species (Glaucomys sabrinus), we focused on Southern Flying Squirrels (G. volans). Using flow-through respirometry, we measured the relationship between metabolic rate, evaporative water loss, and body temperature at high ambient temperatures. We also measured core body temperature in free-ranging flying squirrels using temperature-sensitive data loggers. We detected no significant increase in metabolic rate up to ambient temperatures as high as 40 °C. However, evaporative water loss increased at temperatures above 36.2 °C. Free-ranging body temperature of flying squirrels followed a circadian pattern with a ~2 °C difference between active and resting phase modal body temperatures. Rest-phase body temperatures were influenced by environmental temperatures with higher resting temperatures observed on days with higher daily maximum ambient temperatures but not to an extent that energy or water costs were significantly increased during rest. We found that, due to a relatively high level of thermal tolerance, high ambient temperatures are unlikely to cause an energetic strain on Southern Flying Squirrels. However, these findings do not preclude negative impacts of high ambient temperatures on the northern species, and these may still play a role in the changing distributions of Glaucomys in North America.

Acute heat trauma model in rats, gender-dependent thermoresistance, and screening of potential thermoprotectors

Heat trauma (HT) is an urgent medical and social problem. Heat damage is a widespread effect of the environment on humans, driven by global warming, military conflicts, technological disasters, work in hot environments, and engagement in extreme sports and tourism. The aim of the study: to propose a model of acute HT in rats that does not cause the death of animals, to determine the dependence of thermoresistance on gender, and to compare the effectiveness of the thermoprotective effects of a range of non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, and glucosamine hydrochloride in this model. Materials and Methods: The experiment was conducted on adult white rats of both genders. Acute HT was modelled by using a specially developed method involving heat exposure to animals at +55 °C for 30 minutes, followed by a recovery period of 60 minutes. Rectal temperature was measured every 15 minutes. The degree of hyperthermia in males and females was determined. The presence and intensity of the thermoprotective effect of glucosamine hydrochloride (G h/ch), diclofenac sodium, acetylsalicylic acid (ASA), nimesulide, etoricoxib, celecoxib, and paracetamol were evaluated through intragastric administration 60 minutes before heat exposure. The results were analyzed using the STATISTICA 12.0 program. Results: It was established that heat exposure at +55 °C for 30 minutes effectively replicates acute HT in rats without causing animal fatalities, adhering to bioethical requirements. Body temperature increases by 10-13 %, characterized as a heat stroke. Occasionally, thermoresistant animals are encountered, where the temperature increase during the first 15 minutes of exposure is less than 1 °C. These animals should not be used for further modelling of heat trauma. Male rats are more sensitive to the effect of high environmental temperatures than females, exhibiting greater hyperthermia (temperature increase of 5.03±0.39°C compared to 3.72±0.22 °C in females, p<0.01). The thermoprotective effect of glucosamine hydrochloride depends on gender, being more pronounced in males. Among the 6 tested COX inhibitors, the most significant thermoprotective effect was observed in the highly selective COX-2 inhibitor celecoxib and the weakly selective central inhibitor paracetamol, warranting in-depth research into their impact on organ and system states following heat trauma, as well as the mechanisms of their thermoprotective action. The thermoprotective effect is not associated with selectivity towards COX (cyclooxygenase): it is not observed in the highly selective COX-2 inhibitor etoricoxib and moderately selective COX-2 inhibitor nimesulide, as well as in non-selective COX inhibitors such as diclofenac sodium and aspirin, which also slows down the recovery of body temperature after heat exposure. Conclusions: A convenient and simple model of acute HT in rats is proposed, demonstrating higher thermosensitivity and a more pronounced thermoprotective effect of glucosamine hydrochloride in males. A significant thermoprotective effect was identified in celecoxib and paracetamol, surpassing other investigated NSAIDs. The mechanism and specific features of this effect require further clarification

Effects of the selection process on malondialdehyde, catalase, superoxide dismutase levels, and the performance of gilts under tropical environmental conditions.

Gilt selection has the propensity to improve reproductive performance and promote longevity. However, the impact of this process on oxidative stress biomarker levels remains to be unraveled under tropical conditions. This study aimed to determine the effect of management processes during gilt selection on serum malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) levels, and the performance of replacement gilts under tropical environmental conditions. Two groups of 90 crossbred gilts (mean age: 9.72 ± 0.097 weeks) were selected 2 weeks apart, allotted to six pens of 30, and raised in an open barn with shaded roofs. Following their respective entry weeks, gilts in groups one and two were subjected separately to three subsequent selection processes (involving movements, handling, and examination of structural and reproductive traits) at weeks 12, 17, and 24 in the replacement barn. Grower, finisher, and gestation diets were supplied ad libitum for 25 weeks. Environmental temperature (°C), humidity (%), and light (lux) were recorded. Malondialdehyde, CAT, and SOD levels were assayed using blood samples collected on day 1 of experiment (PRE), and at week 24 in replacement barn (POST). Feed intake, weight gain, and percent selected at week 24 were 1.89 versus 1.90 kg/day, 0.81 versus 0.76 kg/day, and 75.23% versus 64.45% for groups one and two, respectively. Sickness, death, slow growth, leg, and reproductive problems caused 24.76% versus 35.55% of removals in groups one and two, respectively. Serum biomarkers were insignificant at PRE but were elevated at POST, with mean values of 14.25 versus 13.84 uM, 5.10 versus 3.26 nmol/min/mL, and p < 0.05, and 1.13 versus 1.68 U/mL and p < 0.05 for MDA, CAT, and SOD in groups one and two, respectively. The impact of the selection process was meager compared to the adverse effect of high environmental temperatures. The management and selection of replacement gilts in an uncontrolled environmental temperature increase the risk of oxidative stress, especially in tropical regions.

Heat stress and sperm production in the domestic cat

This study aimed to assess 1) the effect of high environmental temperatures on sperm production and 2) the effectiveness of a temperature-humidity index (THI) to predict the degree of thermal stress in a cat model. Semen collection was performed by electroejaculation for 18 mo in 20 tomcats maintained under controlled photoperiod. Still, temperature and humidity were not experimentally manipulated to describe the effect of natural climate conditions on seminal samples. Ejaculates (n = 512) were then grouped according to temperature records of the sampling day and compared by temperature and THI index. Significant lower sperm parameters and increase sperm tail abnormalities were observed during warm environments (temperature and THI). Concentration and total sperm count were the most affected parameters. Environmental temperatures of 28.5 °C with 54% relative humidity (THI = 77.07) and 27.9 °C with 66% humidity (THI = 77.84) were upper thresholds of moderate thermal stress. Moreover, days with relative humidity near 90% led to severe thermal stress with temperatures as low as 26.6 °C (THI = 78.88). The current study demonstrates the detrimental effect of high environmental temperatures on sperm quality in the domestic cat. This effect is observed at lower temperatures when high relative humidity is present. In this sense, the THI was a reliable predictor of the magnitude of thermal stress experienced by cats. Thus, cats from reproductive programs should be maintained under controlled photoperiod cycles with temperatures around 20 °C and humidity around 70% to avoid semen detrimental effects.

Side effects of high environmental temperature on reproductive efficiency of ruminants

Side effects of high environmental temperature on reproductive efficiency of ruminants

Side effects of high environmental temperature on reproductive efficiency of ruminants

Side effects of high environmental temperature on reproductive efficiency of ruminants

Effect of Angiotensin receptor blockade on Plasma Osmolality and Neurohumoral Responses to High Environmental Temperature in Rats Fed a High Salt Diet

Plasma osmolality (pOsmol) and neurohumoral signals play important roles in the pathophysiology of cardiovascular diseases. Our study investigated the effect of high environmental temperature (HET) on neurohumoral responses and pOsmol in rats fed a high salt diet (HSD), with and without angiotensin II receptor blockade (ARB), using telmisartan. Fifty-six male 8-week old Sprague-Dawley rats (95-110g) were randomly assigned into seven groups of 8 rats. These included control rats (I) fed with 0.3% NaCl diet (normal diet, ND); salt-loaded rats (II) fed with 8% NaCl (high salt) diet; ND rats (III) exposed to HET (38.5±0.5oC ) 4 hours daily per week; rats (IV) fed with 8% NaCl diet and exposed to HET daily. Others included rats (V) fed with 8% NaCl diet and treated with telmisartan (30mg/kg); ND rats (VI) exposed to HET and treated with telmisartan; rats (VI) fed with 8% NaCl diet, exposed to HET and treated with telmisartan. Plasma angiotensin II, aldosterone, vasopressin and norepinephrine (NE) concentrations were determined by ELISA technique; pOsmol from plasma K+, Na+ and Urea. HSD combined with HET in rats synergistically increased pOsmol (P&lt;0.001) with an associated non-synergistic rise in fluid intake (P&lt;0.001), fluid balance (P&lt;0.001), plasma angiotensin II (P&lt;0.01) and aldosterone (P&lt;0.05), NE (P&lt;0.001) and vasopressin (P&lt;0.05) concentrations compared to control. Telmisartan did not alter pOsmol in all the treated-rats, but normalized fluid intake levels and plasma vasopressin in the rats exposed to either HSD or HEt alone. Prolonged exposure of rats to hot environment exacerbated the effect of excess dietary salt on pOsmol, with no effect on angiotensin II-mediated neurohumoral responses

Effect of Angiotensin receptor blockade on Plasma Osmolality and Neurohumoral Responses to High Environmental Temperature in Rats Fed a High Salt Diet.

Plasma osmolality (pOsmol) and neurohumoral signals play important roles in the pathophysiology of cardiovascular diseases. Our study investigated the effect of high environmental temperature (HET) on neurohumoral responses and pOsmol in rats fed a high salt diet (HSD), with and without angiotensin II receptor blockade (ARB), using telmisartan. Fifty-six male 8-week old Sprague-Dawley rats (95-110g) were randomly assigned into seven groups of 8 rats. These included control rats (I) fed with 0.3% NaCl diet (normal diet, ND); salt-loaded rats (II) fed with 8% NaCl (high salt) diet; ND rats (III) exposed to HET (38.5±0.5oC ) 4 hours daily per week; rats (IV) fed with 8% NaCl diet and exposed to HET daily. Others included rats (V) fed with 8% NaCl diet and treated with telmisartan (30mg/kg); ND rats (VI) exposed to HET and treated with telmisartan; rats (VI) fed with 8% NaCl diet, exposed to HET and treated with telmisartan. Plasma angiotensin II, aldosterone, vasopressin and norepinephrine (NE) concentrations were determined by ELISA technique; pOsmol from plasma K+, Na+ and Urea. HSD combined with HET in rats synergistically increased pOsmol (P<0.001) with an associated non-synergistic rise in fluid intake (P<0.001), fluid balance (P<0.001), plasma angiotensin II (P<0.01) and aldosterone (P<0.05), NE (P<0.001) and vasopressin (P<0.05) concentrations compared to control. Telmisartan did not alter pOsmol in all the treated-rats, but normalized fluid intake levels and plasma vasopressin in the rats exposed to either HSD or HEt alone. Prolonged exposure of rats to hot environment exacerbated the effect of excess dietary salt on pOsmol, with no effect on angiotensin II-mediated neurohumoral responses.

Effects of different planes of milk feeding and milk total solids concentration on growth, ruminal fermentation, health, and behavior of late weaned dairy calves during summer

BackgroundIn recent years, there has been an increasing interest in using high quantities of milk or milk replacer (MR) in heat-stressed calves to alleviate the negative effects of high environmental temperatures on their performance. However, observations have indicated a decline in growth performance in the weaning and post-weaning period, which might be optimized with increasing total solids (TS) in milk and weaning age. This study aims to optimize the effects of higher quantities of milk on late weaned calves' performance by increasing TS concentration or delivery route in summer conditions.MethodForty-eight newborn Holstein calves were used in a 2 × 2 factorial arrangement with the factors of pre-weaning total plane of milk (PM) intake (low vs. high) and milk TS content (12% vs. 17%). The treatments were (1) low PM (LPM) intake with 12% TS (TS intake = 45.9 kg), (2) LPM intake with 17% TS (TS intake = 65.1 kg), (3) high PM (HPM) intake with 12% TS (TS intake = 63.7 kg); and (4) HPM intake with 17% TS (TS intake = 90.3 kg). Calves were weaned at d 83, and the study was terminated at d 103 of age. Performance data (every 10 day), skeletal growth (d 80 and 100), ruminal fermentation parameters (d 48 and 91), and behavioral measurements (d 69, 70, 93 and 94) were analyzed as repeated measurements with PROC MIXED of SAS 9.4 (SAS Institute Inc., Cary, NC).ResultsCalves receiving HPM consumed less PMR from d 44 to 83 of age, but they had higher ADG from d 24 to 53 of age compared to those fed LPM (PM × age, P < 0.001). In addition, calves receiving milk with 17% TS had lower PMR intake from d 14 to 83 of age, but greater ADG from d 34 to 53 compared to those receiving milk with 12% TS (TS × age, P < 0.001). Calves that received HPM had greater skeletal growth parameters compared to LPM-fed calves, with a similar effect evident for calves fed milk with 17% TS compared with those fed milk with 12% TS. Calves receiving milk with 17% TS had greater fecal scores and diarrhea occurrence than those fed milk with 12% TS in HPM, but not LPM.ConclusionsIncreasing PM and milk TS concentration improved growth in summer-exposed calves as demonstrated by increased pre-weaning ADG, pre- and post-weaning BW, and structural growth.

Climate change and heat stress: Impact on production, reproduction and growth performance of poultry and its mitigation using genetic strategies.

Heat stress is an important environmental determinant which adversely affects the performance of poultry worldwide. The present communication reviews the impact of heat stress on production, reproduction and growth performance of poultry, and its alleviation using genetic strategies. The adverse effects of high environmental temperature on poultry include decrease in growth rate, body weight, egg production, egg weight, egg quality, meat quality, semen quality, fertility and hatchability, which cause vast financial losses to the poultry industry. High ambient temperature has an antagonistic effect on performance traits of the poultry. Thus, selection of birds for high performance has increased their susceptibility to heat stress. Additionally, heat burden during transportation of birds from one place to another leads to reduced meat quality, increased mortality and welfare issues. Molecular markers are being explored nowadays to recognize the potential candidate genes related to production, reproduction and growth traits for selecting poultry birds to enhance thermo-tolerance and resistance against diseases. In conclusion, there is a critical need of formulating selection strategies based on genetic markers and exploring more genes in addition to HSP25, 70, 90, H1, RB1CC, BAG3, PDK, ID1, Na, F, dw and K responsible for thermoregulation, to improve the overall performance of poultry along with their ability to tolerate heat stress conditions.

Effects of Alchemilla vulgaris on growth performance, carcass characteristics and some biochemical parameters of heat stressed broilers

This study aimed to investigate the effects of Alchemilla vulgaris (A. vulgaris) on growth performance, carcass characteristics, and biochemical parameters in broilers exposed to high environmental temperature conditions. A total of 45 broilers of 21 days of age (Ross 308) were used and grouped as the control group (C), and the groups with the addition of 1% (G1), or 3% (G2) A. vulgaris to chicken diet, respectively. In this study, the body weights of heat stressed broilers were significantly different on the 35th day and onwards. Feed intake was higher in the control group. Feed conversion ratio (FCR) was better in groups G1 and G2 compared to control on the 36th and 42nd day, the FCR was better on the 21st- 42nd days. The highest hot and cold carcass performance were observed in group G2 (79.72±0.93% and 78.02±0.99, respectively), and the lowest values were observed in group C (76.26±1.13% and 75.70±1.20%, respectively). A. vulgaris, reduced serum malondialdehyde (MDA) levels as numerically, and suppressed lipid peroxidation in a dose-dependent manner. It had significant effects on monocytes (MON %, MON count), platelets (PLT), and plateletcrit (PCT) parameters only. In conclusion, the deleterious effects of high environmental temperature in broilers could be partially reversed by A. vulgaris addition to the diets between days 21 and 42.

Influence of pre-slaughter environmental temperature on meat quality of crossbred Pigs of Andhra Pradesh

This study aimed to investigate the effect of high environmental temperature on meat quality traits of crossbred pigs brought for slaughter to the experimental abattoir of the Department of Livestock Products Technology, NTR College of Veterinary Science, Sri Venkateswara Veterinary University, Andhra Pradesh, India. High pre-slaughter environmental temperature significantly (P<0.05) influenced the meat quality of pigs. Pigs exposed to high environmental temperatures had recorded significantly (P<0.05) lower pH values at 24 hr post-mortem with low heme iron content and recorded significantly higher drip losses. Intramuscular fat and crude protein contents were not affected significantly (P<0.05). Serum lactate, glucose, cortisol, and LDH levels differed significantly with increasing environmental temperatures. A significant correlation was noticed with the levels of LDH to serve as a predictor of meat quality.

Effects of dehydration on thermoregulatory behavior and thermal tolerance limits of Rana catesbeiana ().

Predicting the effects of high environmental temperatures and drought on populations requires understanding how these conditions will influence the thermoregulatory behavior and thermal tolerance of organisms. Ectotherms show proportional (fine-tuned) and all-or-none (abrupt) responses to avoid overheating. Scattered evidence suggests that dehydration alters these behavioral responses and thermal tolerance, but these effects have not been evaluated in an integrative manner. We examined the effects of hydration level on the behavioral thermoregulation and behavioral and physiological thermal limits of the "bullfrog" (Rana catesbeiana), a well-studied and important invasive species. To examine the effects of dehydration on proportional responses, we compared the Preferred Body Temperatures (PBT) of frogs with restricted and unrestricted access to water. To assess the effect of dehydration on all-or-none responses, we measured and compared the Voluntary Thermal Maximum (VTMax) at different hydration levels (100%, 90%, 80% of body weight at complete hydration). Finally, to understand the effect of dehydration on physiological thermal tolerance, we measured the Critical Thermal Maximum (CTMax) of frogs at matched hydration levels. PBT, VTMax, and CTMax all decreased in response to higher dehydration levels. However, bullfrogs changed their PBT more than their VTMax or CTMax in response to dehydration. Moreover, some severely dehydrated individuals did not exhibit a VTMax response. We discuss the implications of our results in the context of plasticity of thermoregulatory responses and thermal limits, and its potential application to mechanistic modeling.

Intranidal temperature and body size of Africanized honey bees under heatwaves (Hymenoptera: Apidae)

It is generally accepted that temperate subspecies of honey bees can maintain stable temperatures inside their nests; however, little information is available on the cooling ability of tropical honey bees and the effect of high environmental temperatures on individuals. In this study, we registered temperatures in the brood area of strong- and medium-populated colonies of Africanized honey bees during heatwaves (maximum environmental temperature 44 °C) between April and May in the tropical Yucatan Peninsula of Mexico. To evaluate the effect on colonies, we compared the body size of workers produced under high temperatures in the field and siblings produced at stable 34–35 °C laboratory conditions. We found that in the field, temperatures of the brood nest in both types of colony can increase above 36 °C during the hottest part of the day, especially in less strong colonies. Workers produced in the field were significantly smaller, compared to those reared in the lab at stable temperatures. This is a first study reporting body size reduction in honey bees as a consequence of possible thermoregulation disruption during heatwaves. We discuss our results considering potential effects of heat stress to Africanized honey bee colonies and tropical beekeeping.

Effect of zinc and probiotics supplementation on performance and immune organs morphology in heat stressed broilers

The dietary supplementation of trace minerals and probiotics has long been practiced to reduce the harmful effects of high environmental temperature in poultry. The study aimed to assess the effect of single or combined supplementation of ZnSO4•H2O and probiotic (Protexin®) on the growth performance, gut biometry and immune organs histomorphology in broilers reared under cyclic heat stress. For this purpose, 280 day-old broiler chicks were randomly divided into seven groups designated as control (basal diet), HS (heat stress + basal diet), HS-Zn30 (HS + 30 mg ZnSO 4 •H 2 O/kg feed), HS-Zn60 (HS + 60 mg ZnSO 4 •H 2 O/kg feed), HS-Pro (HS + 0.1 g Protexin®/kg feed), HS-Zn30-Pro (HS + 30 mg ZnSO 4 •H 2 O/kg feed + 0.1 g Protexin®/kg feed), and HS-Zn60-Pro (HS + 60 mg ZnSO 4 •H 2 O/kg feed + 0.1 g Protexin®/kg feed). Each group consisted of five replicates (8 birds per replicate). The birds were fed on starter (0 - 21days) and grower (22 - 42 days) diets. From day 22 onwards, the birds were exposed to cyclic heat stress (temperature and relative humidity at 35 ± 1 °C and 75 ± 5% respectively) for 8 hours. The results revealed that birds exposed to heat stress showed significant decrease in body weight (BW) and increase in feed conversion ratio (FCR) compared to the control group. The dietary supplementation of ZnSO 4 •H 2 O and probiotic either singly or in combination improved BW and FCR throughout the experimental period in heat-stressed broilers. Area of lymphatic nodule and lymphoid follicle in caecal tonsils and bursa of Fabricius increased in HS-Pro, HS-Zn30-Pro and HS-Zn60-Pro groups compared to HS group. In conclusion, zinc and probiotics combination partially improved performance and immune organs histomorphology in heat-stressed broilers. _ Keywords : Chicken, heat stress, immune organ, morphology, Protexin

A Systematic Review of Heat Load in Australian Livestock Transported by Sea.

Simple SummaryThe transport of livestock by sea (‘live export’) is an important contemporary animal welfare issue in Australia. There is particular concern for the effects of heat load on the welfare of sheep being shipped live from Australia to the Middle East during the Northern Hemisphere summer. To reduce bias in a contentious context, we performed a systematic review of the literature relevant to Australian sea transport, heat load, and livestock. We discuss the factors contributing to harmful heat load, pathways for mitigating risks and existing knowledge gaps. We identified several areas requiring research to address these knowledge gaps.The transport of animals by sea (‘live export’) is one of the most important current animal welfare issues in Australian society. Recent media attention has highlighted concerns regarding the effects of high environmental temperature and humidity on the welfare and mortality of sheep being shipped live from Australia to the Middle East, especially during the Northern Hemisphere summer. To improve understanding of how and why harmful heat load occurs, we systematically reviewed Australian research into heat load and sea transport. High thermal load occurs during the sea transport of sheep and cattle from Australia when animals are subject to hot and humid environmental conditions and cannot remove heat generated by metabolic processes in the body, potentially also gaining heat from the environment. Several approaches have been proposed to mitigate these risks, including avoidance of voyages in hot seasons, selection of heat-resistant livestock breeds, reducing stocking density, and improved ventilation. We identified a lack of scientific literature relating to heat load in animals transported by sea and considerable potential for bias in the literature that was found. We identified the following priority research areas: (i) experimental manipulation of variables thought to influence the incidence and severity of harmful heat load, including sheep density; (ii) further assessment of the Heat Stress Risk Assessment (HSRA) model used to predict heat load events, and (iii) development of a suite of animal welfare indicators that may allow identification of ‘at risk’ sheep before they reach debilitating heat load condition. Addressing these knowledge gaps will assist efforts to reduce the frequency and intensity of harmful heat load events.

Molecular and Biochemical Aspects of the Ontogenesis of Eukaryotes Under Global Warming

Global warming is an irreversible process resulting in the deterioration of living conditions for various organisms, including the most important agricultural species. So-called σ32 factor of Escherichia coli is embedded into the RNA thermosensor in the λ cIII gene and plays an important role in the regulation of bacterial response to heightened temperatures. Expression of heat/cold shock genes and some virulence genes in response to temperature changes is coordinated by the genome. There are some known RNA thermosensors with different structures that provide a functional control of the diversity of cellular processes. The most common RNA thermosensor is the ROSE element suppressing expression of heat shock genes. A common feature of all ROSE elements is the presence of the G residue opposite to the SD sequence since this nucleotide is functionally important and its elimination makes the RNA thermosensor insensitive to high temperatures. In this paper, we describe molecular sequences (RNA thermosensors) whose chemical compounds influence on the homeostatic temperature regulation, namely, on the corresponding enzymes. Though the data on RNA thermosensors were obtained for microorganisms, it may be possible in the long run to change the animal genome at the molecular level by the insertion of these sequences or cultivation of symbiotic microorganisms, which may be used for production of biologically active compounds. In addition, such insertions would probably be able to reduce the negative effect of high environmental temperatures on living organisms.

The importance of propolis in alleviating the negative physiological effects of heat stress in quail chicks.

Heat stress is one of the most detrimental confrontations in tropical and subtropical regions of the world, causing considerable economic losses in poultry production. Propolis, a resinous product of worker honeybees, possesses several biological activities that could be used to alleviate the deleterious effects of high environmental temperature on poultry production. The current study was aimed at evaluating the effects of propolis supplementation to Japanese quail (Coturnix coturnix japonica) diets on the production performance, intestinal histomorphology, relative physiological and immunological parameters, and selected gene expression under heat stress conditions. Three hundred one-day-old Japanese quail chicks were randomly distributed into 20 wired-cages. At 28 d of age, the birds were divided into 2 temperature treatment groups; a normal at 24°C (C group) and a heat stress at 35°C (HS group). The birds in each group were further assigned to 2 subgroups; one of them was fed on a basal diet without propolis supplementation (-Pr subgroup) while the other was supplemented with propolis (+Pr subgroup). Production performance including body weight gain, feed intake and feed conversion ratio were measured. The intestinal histomorphological measurements were also performed for all treatment groups. Relative physiological parameters including body temperature, corticosterone hormone level, malondialdehyde (MDA) and free triiodothyronine hormone (fT3), as well as the relative immunological parameters including the total white blood cells count (TWBC’s), heterophil/lymphocyte (H/L) ratio and lymphocyte proliferation index, were also measured. Furthermore, the mRNA expression for toll like receptor 5 (TLR5), cysteine-aspartic protease-6 (CASP6) and heat shock proteins 70 and 90 (Hsp70 and Hsp90) genes was quantified in this study. The quail production performance was significantly (P<0.05) impaired by HS treatment, while Pr treatment significantly improved the quail production performance. The villus width and area were significantly (P<0.05) lower in the HS compared to the C group, while Pr treatment significantly increased crypts depth of quail. A negative impact of HS treatment was observed on the physiological status of quail; however, propolis significantly alleviated this negative effect. Moreover, quail of the HS group expressed lower immunological parameters than C group, while propolis enhanced the immune status of the quail. The relative mRNA expression of TLR5 gene was down-regulated by HS treatment while it was up-regulated by the Pr treatment. Furthermore, the positive effects of propolis in HS-quail were evidenced by normalizing the high expressions of CASP6 and Hsp70 genes when compared to the C group. Based on these results, the addition of propolis to quail diets as a potential nutritional strategy in order to improve their performance, especially under heat stress conditions, is recommended.

Axial crush behavior and energy absorption capability of foam-filled GFRP tubes under elevated and high temperatures

Foam-filled circular composite tube has been widely used in safety design of automobile, space craft recovery and so on due to its advantage of high energy absorption, light weight and anti-corrosion. But the axial crush behavior and energy absorption capability of foam-filled composite tubes are threatened by elevated and high temperatures. In practice, the effects of high temperatures cannot be ignored because composites and foam are sensitive to temperature. In this paper, an experimental investigation was carried out to evaluate the effectiveness of energy absorption of foam-filled circular glass fiber reinforced plastic (GFRP) tube under elevated and high temperatures. The temperature range was from 20°C to 110°C, covered the glass transition temperature (92°C). In the meantime, the effects of high environmental temperatures on failure mode, crush force efficiency, energy ductility coefficient and specific energy absorption were also studied. The test results demonstrated that the axial crush behavior and energy absorption capacity of foam-filled GFRP tubes were determined by the environmental temperature. The foam-filled GFRP tubes can achieve top crashworthiness performance when the environmental temperature was less than 70°C.

高温刺激对蟾蜍免疫活性和能量消耗的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 高温刺激对蟾蜍免疫活性和能量消耗的影响 DOI: 10.5846/stxb201306161715 作者: 作者单位: 浙江师范大学生态研究所,浙江师范大学生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(30800129, 31270457) The effects of hyperthermia on immunocompetence and energy consumption in Bufo bufo gargarizans Author: Affiliation: Institute of Ecology,Zhejiang Normal University,Institute of Ecology,Zhejiang Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:全球气候变化是导致全世界两栖动物种群衰退和灭绝的重要因素之一。为了解无尾两栖类在气候异常导致的极端高温下的生理反应特征和相关适应机制,以雄性中华大蟾蜍(Bufo bufo gargarizan)为对象,研究该物种在高温刺激(环境温度由22 ℃迅速升至32 ℃)0、6、12、24、48 h后的非特异性免疫活性和能量消耗的变化情况。研究结果:与对照组(22 ℃)比较,高温刺激可显著抑制外周血细胞吞噬活性;而脾脏巨噬细胞呼吸爆发在高温刺激下呈现出先增强后减弱的趋势。高温刺激导致血糖含量在第24和48 h显著低于对照组,而对肝糖原含量无显著影响。处理组精巢ATP含量逐渐升高,并于24和48 h显著高于对照组;处理组Na+-K+-ATPase活性随时间呈现出先下降后上升稳定的趋势,但与对照组相比均无显著性差异,;处理组Ca2+-Mg2+-ATPase活性在不同时期与对照组相比均无显著性差异。研究结果说明,高温刺激可显著抑制中华大蟾蜍的非特异性免疫功能,并导致血糖的大量消耗;当面对高温胁迫时,雄性大蟾蜍可能会投入更多的能量来维持性腺的正常发育。 Abstract:Global climate change is a key factor which leads to either a decline or an extinction of amphibian populations worldwide. This paper investigates the effects of high environmental temperatures on non-specific immunity and energy consumption in the male toads (Bufo bufo gargarizans). We found that peripheral blood cell phagocytosis decreases while spleen macrophage respiratory burst activity transiently increases in high-temperature toads (32 ℃) versus control toads (22 ℃). Blood glucose levels decrease in high-temperature toads after 24 h and 48 h exposure versus control toads, while hepatic glycogen content remains unchanged. In addition, the ATP content in the high-temperature toad testis gradually increases and reaches significant levels after 24 h and 48 h exposure versus control toads. Na+-K+-ATPase and Ca2+-Mg2+-ATPase activity show no significant changes. Our results indicate that high environmental temperatures cause a decline in immunocompetence, an increase in glucose consumption, and an accumulation of energy (ATP) within the testis in Bufo bufo gargarizans. 参考文献 相似文献 引证文献