Environmental Heat Stress Research Articles

Linseed oil in boar’s diet during high temperature humidity index (THI) period improves sperm quality characteristics, antioxidant status and fatty acid composition of sperm under hot humid sub-tropical climate

Environmental heat stress in sub-tropical climates negatively impacts boar semen production and its quality. The present study aimed to examine the heat stress alleviating effects of dietary linseed oil on semen quality and antioxidant status of boar, in the summer and winter seasons in sub-tropical climate. Six Hampshire crossbreed boars were fed with 90 mL linseed oil (treatment) whereas six boars of the same breed were fed 90 mL vegetable oil (control) for sixteen weeks during both season. Sperm quality was assessed for motility, viability, abnormality, acrosomal integrity, and Hypo-osmotic swelling test (HOST). Sperm velocity attributes were assessed by computer-assisted semen analysis (CASA). Antioxidants (glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC and nitric oxide; NO) and lipid peroxidation (malondialdehyde; MDA) were measured in seminal plasma and serum. Gas chromatography-mass spectrometry (GC-MS) was used for the estimation of fatty acid composition of seminal plasma and spermatozoa. Feeding linseed oil to the boars significantly (p < 0.05) improved sperm quality at the fresh stage and after 72 h of liquid storage in both season. There was a significant (p < 0.01) effect of treatment and season on semen quality parameters. Significant boar (p < 0.05) effect was recorded on reaction time, semen volume, sperm abnormality, acrosomal integrity and HOST reactive sperm. There was a significant (p < 0.01) effect of treatment and season on the velocity attributes viz. VAP, VSL, VCL, ALH, BCF and STR%. Linseed oil supplementation significantly (p < 0.01) enhanced antioxidant and lowered MDA levels in serum as well as seminal plasma. The concentration of alpha-linolenic (ALA), arachidonic and docosahexaenoic (DHA) fatty acids were significantly (p < 0.01) increased in seminal plasma and sperm after linseed oil supplementation. In conclusion, linseed oil supplementation to boar during high THI months improved the semen quality parameters viz. semen volume, sperm concentration, and progressive motile sperm, along with enhanced antioxidant capacity.

Analyzing environmental heat stress under changing work conditions: A sensor‐based monitoring solution

AbstractHot stressful work conditions impose subsequent suppressions on workers' wellbeing resulting in heat‐related morbidities, reduced productivity, and economic burden. Heat stress evaluations require costly monitoring tools that may be uneconomical while monitoring multiple locations simultaneously under the targeted workplace, especially in industrially developing countries. With recent technological advancements, sensor‐based intelligence could enable environmental heat stress monitoring at a substantially lesser price than costlier monitoring tools. In the present study, a sensor‐based approach has been utilized to develop a low‐cost data acquisition system involving widely used temperature‐humidity (THu) based indices and environmental sensors for monitoring heat stress parameters under three different work environments (i.e., indoor, outdoor, foundry). Notable variations were observed among respective work environments for the evaluated heat stress parameters. Higher heat exposures were attributable to the foundry and outdoor conditions than indoor. Based on the bivariate correlation analysis, strong associations were observed among respective indices (p &lt; .01). For wet bulb globe temperature (WBGT), strong association was observed with modified discomfort index and fighter index of thermal stress (R2 = .979) followed by oxford index (R2 = .973) and discomfort index (R2 = .958). Australian Bureau of Metrology (ABM) WBGT approximation overestimated heat exposure values under the respective environments, indicating the approximated WBGT values monitored using THu sensor units were not wholly reliable. The absence of radiant effects and air velocity is a limiting factor in the present study. However, the proposed prototype could have additional integration capabilities w.r.t several remedial control measures like risk‐based early warning systems, automation controls, and real‐time data monitoring and analysis for multiple locations simultaneously, with potential payoffs like cost‐effectiveness and energy savings.

Associations Between Ambient Temperature and Circulating Maternal One-carbon and Amino Acid Metabolites in Pregnancy

ObjectivesExcessive ambient temperature closely linked to climate change is an imminent threat to the health of mothers and children globally. Recent studies have shown detrimental associations between high temperatures during pregnancy and birth outcomes. The goal of this study was to examine relationships between circulating metabolites in the mother and environmental temperature in a resource-limited setting. MethodsThe study was a secondary analysis employing data from the Women First (WF) trial conduced in Thatta, Pakistan. As part of the trial, women of child-bearing age either consumed a comprehensive maternal nutritional supplement (MNS) prior to conception until delivery (Arm 1), from 12 wk gestation until delivery (Arm 2); or were not supplemented with MNS Arm 3. Daily maximum air temperatures were acquired from the closest surface observation systems (n = 131). Average daily maximum temperatures (Tmax) for a 90-day window representing the 1st trimester of pregnancy was calculated for each participant. The number of days in this period when the Tmax was > 39°C was computed to assess ‘heat stress days’. Maternal blood was collected on dried blood spot (DBS) cards at 34 wk gestation. A targeted metabolomics assay measuring concentrations of 23 metabolites was performed on DBS samples using LC-MS/MS. ResultsLinear regression was employed to assess the associations between ambient temperature in the 1st trimester and metabolite levels (z-scores). Models were adjusted for MNS supplementation. Significant associations between Tmax in the 1st trimester and 7 metabolites were observed (FDR p-values < 0.05). Of these, maternal choline concentrations were negatively correlated with maximal temperature in the 1st trimester (β = –0.063, p = 4.3e-10). Concentrations of glutamine, histidine, arginine, symmetrical-dimethylarginine, methionine and cysteine were positively associated (p < 0.05) with daily maximal temperature. ConclusionsCollectively, the findings indicate that exposure to excessive heat stress in the first trimester is associated with lower choline levels and other metabolites important in blood pressure regulation. While the findings are associative, our results point to underlying mechanistic alterations in maternal circulation in concert with environmental heat stress. Funding SourcesBill & Melinda Gates Foundation; NIH/NICHD/ODS.

Reducing the Fermentability of Wheat with a Starch Binding Agent Reduces Some of the Negative Effects of Heat Stress in Sheep.

Simple SummaryHeat stress is one of the major problems affecting the thermotolerance of livestock in Australia and in many parts of the world. Dietary interventions are considered to be one of the effective strategies to beat the heat. Hence, this study evaluated the benefits of reducing the fermentability of wheat grains (BioprotectTM) in the diet of Merino lambs. These results indicated that Bioprotect supplementation had a positive effect on the respiratory rate and heart rate of heat-stressed lambs.The objective of this study was to investigate the effects of reducing the fermentability of grains on thermoregulatory responses in heat stressed (HS) lambs. To achieve this, wheat grain treated with a commercial starch binding agent, Bioprotect, is compared to maize, which has already demonstrated effects in ameliorating heat stress-induced thermoregulation responses and untreated wheat grains. An initial in vitro experiment was conducted to examine cumulative gas production from the fermentation of wheat grain with different dosages of the commercial starch binding agent, Bioprotect. Based on the in vitro results, an in vivo lamb experiment was conducted using 24 Merino lambs (1 year old; 42.6 ± 3.6 kg BW). The lambs were offered one of three dietary treatments: a wheat-based diet (WD), a Bioprotect treated wheat-based diet (BD), and a maize-based diet (MD). Three successive 1-week experimental periods were conducted with lambs from all dietary groups (P1, P2, and P3). During P1, lambs were exposed to a TN environment and fed a 1.7× Maintenance feed intake (MF) level; in P2, lambs were kept in a HS environment and fed a 1.7× MF level; and in P3, animals were kept in a HS environment and fed a 2× MF level. The in vitro experiment revealed a reduction in cumulative gas production (p < 0.05) from the Bioprotect treated wheat compared to untreated wheat samples. In the in vivo component of the study, the replacement of wheat with maize or 2% Bioprotect-treated wheat reduced the respiration rate (p < 0.001) and heart rate (p ≤ 0.01) of lambs during HS. There was a reduction in the concentration of blood gas variables such as a base excess of blood (BE(b)) and extracellular fluid (BE(ecf)), bicarbonate (CHCO3−), the partial pressure of carbon dioxide (pCO2), the total concentration of carbon dioxide (ctCO2), and sodium (Na+) (p ≤ 0.001 for all) during the periods of HS compared to the thermoneutral conditions. Moreover, BD- and MD-fed lambs had a higher blood potassium concentration (K+) than the WD-fed lambs (p = 0.008). The results of the present study suggest that Bioprotect can be a viable feed treatment strategy for treating rapidly fermentable grains such as wheat to alleviate the effects of HS. Further, Bioprotect-treated wheat could be an option to replace maize in concentrate rations in jurisdictions where maize is cost-prohibitive or unavailable.

Dietary nanoselenium supplementation for heat-stressed rainbow trout: effects on organizational structure, lipid changes, and biochemical parameters as well as heat-shock-protein- and selenoprotein-related gene expression

Nanoselenium (nano-Se) shows unique protective effects against environmental heat stress in rainbow trout as a selenium source additive and free radical scavenger. Accordingly, we investigated the effects of supplementation with different levels of nano-Se (0, 5, and 10 mg/kg) and before and after heat stress (24°C) for different treatment times on the dynamic changes of rainbow trout liver tissue structure, lipid changes, biochemical properties, and gene expression. The results showed that, under heat stress, the fish supplementation of 5 mg/kg nano-Se significantly increased liver glutathione peroxidase (GPx) activity and upregulated expression levels of HSP70b, HSP90a1, GPx1a, and Trx mRNAs, while liver alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), and malondialdehyde (MDA) levels as well as tissue structure damage and lipid accumulation were decreased. Combining the trends for the above indicators indicated that stress began to increase significantly at 8 h. It can be concluded that supplementation with 5 mg/kg nano-Se effectively alleviates stress damage in rainbow trout. Furthermore, stress at 24°C for 8 h can be thought of as a critical time point for the study of heat stress in rainbow trout, with significant changes in response but no serious damage. Thus, these results provide a reference for the addition of nano-Se to rainbow trout feed and provide theoretical and practical guidance for enhancing the resistance of rainbow trout to heat stress.

The Autophagic Response to Acute Exercise in Young Men is Exercise Intensity Dependent and Influenced by Exposure to Heat

Autophagy is a vital cellular mechanism that maintains normal cellular function during acute stressors, including exercise and heat stress, by degrading and recycling damaged or dysfunctional cellular constituents, thereby enabling normal cellular processes to survive the stress insult. Despite implications of exercise being a potent stimulus of autophagy, the relationship between exercise intensity and activation of autophagy remains unclear in humans. Further, while cellular stress associated with exercise is exacerbated when performed in the heat, it is unknown if this is associated with a corresponding change in autophagy. Therefore, we evaluated the hypothesis that autophagy would be exercise‐intensity dependent and that the autophagic response would be enhanced during exercise in the heat. To evaluate this hypothesis, on four separate days, 10 young men (mean [SD]; 22 [2] years) performed 30‐minutes of low‐, moderate‐, and high‐intensity semi‐recumbent cycling (equivalent to 40, 55, and 70% of maximal oxygen consumption) in a non‐heat stress environment (25°C). To assess the superimposing effects of an environmental heat stress, high‐intensity exercise was also performed in the heat (40°C). Mean body temperature (MBT; 0.64*rectal temperature + 0.36*skin temperature) was measured throughout, while autophagy‐related proteins (microtubule associated protein 1 light chain 3 (LC3)‐II and sequesterome‐1/p62 (p62)) were assessed via Western blot before, immediately after, and following 3h and 6h post‐exercise recovery. All proteins were normalized to β‐actin and reported as fold change relative to the respective baseline. Data were compared via a two‐way repeated measures ANOVA with Tukey’s test (α=0.05). No change in MBT occurred during low‐intensity exercise, although a step‐wise increase was observed at end‐exercise during moderate‐ (36.01 [0.36]°C; p&lt;0.01), and high‐intensity exercise (36.32 [0.35]°C; p&lt;0.01), with further increases in the heat (37.40 [0.50]°C; p&lt;0.01) as assessed in the high‐intensity exercise only. While autophagy proteins did not change during low‐intensity exercise, LC3‐II was elevated at the end of moderate‐intensity exercise (1.31 [0.38]; p=0.02), which returned to baseline within 3h. During high‐intensity exercise, LC3‐II increased at end‐exercise (1.59 [0.16]; p&lt;0.01), which remained elevated above baseline at 3h (1.46 [0.28]; p&lt;0.01) and 6h (1.31 [0.22]; p=0.04). Similarly, while LC3‐II was elevated at end‐exercise in the heat above the non‐heat stress condition (2.38 [0.98]; p=0.01), the recovery response was similar between conditions. Changes in p62 were only observed during high‐intensity exercise with (0.65 [0.27]; p=0.03) and without (0.69 [0.10]; p=0.04) heat, which returned to basal levels within 3‐h in both conditions, with no differences between conditions. Taken together, we show that autophagy is exercise‐intensity dependent (given LC3‐II accumulation and p62 degradation are indicative of elevated autophagy) and this response is amplified by the added burden of heat.

Characterizing plant trait(s) for improved heat tolerance in field pea (Pisum sativum L.) under subtropical climate.

Field pea is highly sensitive to climatic vagaries, particularly high-temperature stress. The crop often experiences terminal heat stress in tropical climates indicating the need for the development of heat-tolerant cultivars. Characterization and identification of stress-adaptive plant traits are pre-requisites for breeding stress-tolerant/adaptive cultivar(s). In the study, a panel of 150 diverse field pea genotypes was tested under three different temperature environments (i.e., normal sowing time or non-heat stress environment (NSTE), 15days after normal sowing time or heat stress environment-I (LSHTE-I), and 30days after normal sowing time or heat stress environment-II (LSHTE-II)) to verify the effect of high-temperature environment, genotype, and genotype × environment interaction on different plant traits and to elucidate their significance in heat stress adaptation/tolerance. The delayed sowing had exposed field pea crops to high temperatures during flowering stage by + 3.5°C and + 8.1°C in the LSHTE-I and LSHTE-II, respectively. Likewise, the maximum ambient temperature during the grain-filling period was + 3.3°C and + 6.1°C higher in the LSHTE-I and LSHTE-II over the NSTE. The grain yield loss with heat stress was 25.8 ± 2.2% in LSHTE-I, and 59.3 ± 1.5% in LSHTE-II compared to the NSTE. Exposure of crops to a high-temperature environment during the flowering stage had a higher impact on grain yield than the heat stress at the grain filling period. Results suggested that the reduced sink capacity (pod set (pod plant-1), seed set (seed pod-1)) was the primary cause of yield loss under the heat stress environments, while, under the NSTE, yield potential was mostly attributed to the source capacity (plant biomass). The high-temperature stress resulted in forced maturity as revealed by shrinkage in crop period (5-11%) and reproductive period (15-36%), prominently in long-duration genotypes. The failure of pod set in the upper nodes and higher ovule abortion (7-16%) was noticed under the high-temperature environments, particularly in the LSHTE-II. Multivariate analysis results revealed seed set, pods plant-1, last pod bearing node, and plant biomass as a critical yield determinant under the heat stress. The GGE biplot suggested that the genotypes G-112, G-114, and G-33 had higher potential to sustain yield coupled with higher stability across the environments and, thus, could serve as a source for breeding heat-tolerant high yielding cultivars.

FOLIAR APPLICATION OF SALICYLIC ACID AND CALCIUM CHLORIDE ENHANCE HEAT STRESS TOLERANCE IN TOMATO

The aim of this research was to enhance heat stress tolerance potential in local tomato germplasm through exogenous application of salicylic acid (SA) and calcium chloride (CaCl2). Various concentrations of salicylic acid (e.g., control, 2.5 mM, 3.5 mM and 4.5 mM) and calcium chloride (e.g., control, 0.3 mM, 0.4 mM and 0.5 mM) were applied for the duration of forty days. Physiological parameters include (stomatal conductance, photosynthetic rate, transpiration rate and water use efficiency) as well as biochemical attributes (chlorophyll content, enzyme activities of catalase, peroxidase and superoxidase dismutase) of selected tomato genotypes estimated under heat stress conditions. The results revealed that SA and CaCl2 application enhanced vegetative growth of tomato genotypes as compared with control plants. An increased concentration of SA and CaCl2 showed the improved photosynthetic rate, chlorophyll content and induced transpiration rate and stomatal conductance and antioxidant enzyme activity. The study proved that foliar spray of SA and CaCl2 involved in stabilizing the cell as well as cellular integrity under heat stress environment.

Review Article : Heat stress and poultry: Adaptation to climate change, challenges and opportunities for genetic breeding in Kenya

The Earth’s ambient climatic factors, such as temperature, humidity, solar radiation, and precipitation, vary through time and space due to climate change. Heat stress, one of the major factors affecting poultry production, is a direct result of climate change, resulting in enormous losses for the poultry sector. As a result of heat stress, several physiological changes such as suppressed immunecompetence, oxidative stress, and acid-base balance lead to reduced feed intake, feed efficiency, body weight, meat, egg quality, and sometimes mortality. Adverse effects have necessitated several adjustments in animal husbandry practices such as housing and feeding regimes to be implemented. Modifying the environment in poultry production systems can cushion exposure and compensate for losses in poultry fitness in heat-stressed environments. Some of the modifications that have been tested and shown to be successful in attenuating heat stress in poultry include shade, sprinkling cold water on their bodies, and adjusting diets to reduce metabolic heat production. The extensive genetic diversity of indigenous poultry is essential for climate change adaptation and the continuous enhancement of the genetic stock through breeding adaptive features like heat stress tolerance. The naked neck (Na) and frizzle (gene F) gene have been given attention in recent times in their role to withstand heat stress in poultry. A better understanding of indigenous poultry acclimatization to severe environments, together with methods and tools available for the selection, breeding, and matching indigenous poultry ecotypes to suitable environments, should help to minimize the effects of heat stress on indigenous poultry genetic resource growth, production, and reproduction to sustain food security.

Mineral supplementation (injectable) improved reproductive performance in Holstein cows managed in a warm summer environment.

Sustainability of dairy production depends largely on reproductive efficiency that is affected by heat stress due to high ambient temperature and humidity during summer. Supplementation of minerals has been proposed as a management strategy to minimize adverse impact of heat stress on fertility. The objective of this study was to determine the effects of an injectable mineral supplement (Fosfosan) containing selenium (Se), copper (Cu), potassium (K), magnesium (Mg) and phosphorus (P) on the ovarian structures, reproductive hormones and conception rate of heat-stressed Holstein cows. Sixteen cows were assigned during summer to one of two treatments, a control group (CON; n=8) and a mineral-supplemented group (SUP; n=8). Ambient temperature and relative humidity records were collected and processed to estimate the temperature-humidity index (THI), which confirmed a heat-stressed environment during the study (avg. THI=79.4). Cows were subjected to a fixed-time artificial insemination (FTAI) program using the CIDR-Synch synchronization protocol. Traits indicative of ovarian activity were recorded during and after this protocol, as well as serum concentrations of reproductive hormones. Pregnancy diagnosis was made 28 and 35 d after FTAI. A completely randomized block design with repeated measures over time was performed to study ovarian functional structures and its hormonal profiles. Correlations and regressions were estimated to study relationships between ovarian structures and related hormones. Mineral supplementation did not increase follicular diameter or follicular populations (p>.05), yet tended to increase corpus luteum diameter (p<.10), and it enhanced (p<.01) oestrogen and progesterone serum concentrations and improved (p<.05) cow's conception rate. Diameter of dominant follicles and corpus luteum was correlated (p<.05) with oestrogen and progesterone levels, respectively, but only in mineral-treated cows. Two additional dairy herds were evaluated to confirm that mineral supplementation improved conception rate during the heat stress period (objective 2). Cows from dairy 1 received FTAI during winter (n=401) and summer (n=240), whereas cows from dairy 2 were bred after natural detected oestrus during winter (n=558) and summer (n=314). Conception rates were higher (p<.05) in winter than summer and they improved (p<.05) with mineral supplementation, but only in cows managed during summer. In conclusion, supplementation of minerals enhanced hormonal secretion from ovarian structures and improved conception rate in Holstein cows exposed to summer heat stress.

Wheat endophytes and their potential role in managing abiotic stress under changing climate.

Wheat (Triticum aestivum L.) cultivation differs considerably in respect of soil type, temperature, pH, organic matter, moisture regime, etc. Among these, rising atmospheric temperature due to global warming is most important as it affects grain yield drastically. Studies have shown that for every 1°C rise in temperature above wheat's optimal growing temperature range of 20-25°C, there is a decrease in 2.8days and 1.5mg in the grain filling period and kernel weight, respectively, resulting in wheat yield reduction by 4-6 quintal per hectare. Growing demand for food and multidimensional issues of global warming may further push wheat crop to heat stress environments that can substantially affect heading duration, percent grain setting, maturity duration, grain growth rate and ultimately total grain yield. Considerable genetic variation exists in wheat gene pool with respect to various attributes associated with high temperature and stress tolerance; however, only about 15% of the genetic variability could be incorporated into cultivated wheat so far. Thus, alternative strategies have to be explored and implemented for sustainable, more productive and environment friendly agriculture. One of the feasible and environment friendly option is to look at micro-organisms that reside inside the plant without adversely affecting its growth, known as 'endophytes', and these colonize virtually all plant organs such as roots, stems, leaves, flowers and grains. The relationship between plant and endophytes is vital to the plant health, productivity and overall survival under abiotic stress conditions. Thus, it becomes imperative to enlist the endophytes (bacterial and fungal) isolated till date from wheat cultivars, their mechanism of ingression and establishment inside plant organs, genes involved in ingression, the survival advantages they confer to the plant under abiotic stress conditions and the potential benefits of their use in sustainable wheat cultivation.

Evaluation of environmental and physiological indicators in lactating dairy cows exposed to heat stress.

This study aimed to better understand environmental heat stress and physiological heat strain indicators in lactating dairy cows. Sixteen heat stress indicators were derived using microenvironmental parameters that were measured at the surrounding of cows and at usual fixed locations in the barn by using handheld and fixed subarea sensors, respectively. Twenty high-producing Holstein-Friesian dairy cows (> 30.0kg/day) from an intensive dairy farm were chosen to measure respiration rate (RR), vaginal temperature (VT), and body surface temperature of forehead (FT), eye (ET), and muzzle (MT). Our results show that microenvironments measured by the handheld sensor were slightly warmer and drier than those measured by the fixed subarea sensor; however, their derived heat stress indicators correlated equally well with physiological indicators. Interestingly, ambient temperature (Ta) had the highest correlations with physiological indicators and the best classification performance in recognizing actual heat strain state. Using segmented mixed models, the determined Ta thresholds for maximum FT, mean FT, RR, maximum ET, mean ET, VT, mean MT, and maximum MT were 24.1°C, 24.2°C, 24.4°C, 24.6°C, 24.6°C, 25.3°C, 25.4°C, and 25.4°C, respectively. Thus, we concluded that the fixed subarea sensor is a reliable tool for measuring cows' microenvironments; Ta is an appropriate heat stress indicator; FT, RR, and ET are good early heat strain indicators. The results of this study could be helpful for dairy practitioners in a similar intensive setting to detect and respond to heat strain with more appropriate indicators.

Nicotinamide mononucleotide alleviates heat stress-induced oxidative stress and apoptosis in BMECs through reducing mitochondrial damage and endoplasmic reticulum stress

Heat stress is directly correlated to mammary gland dysfunction in dairy cows, especially in summer. Abnormally high environmental temperature induces oxidative stress and apoptosis in bovine mammary epithelial cells (BMECs). Nicotinamide mononucleotide (NMN) has beneficial effects in maintaining the cellular physiological functions. In this study, we evaluate the protective effect of NMN on heat stress-induced apoptosis of BMECs and explore the potential underlying mechanisms. Our results showed that heat stress considerably decreased cell viability in BMECs, whereas pretreatment of BMECs with NMN (150 μM) for 24 h significantly alleviated the negative effects of heat stress on cells. NMN protected BMECs from heat stress-induced oxidative stress by inhibiting the excessive accumulation of reactive oxygen species (ROS) and increasing the activity of antioxidant enzymes. It also inhibited apoptosis by reducing the ratio of Bax/Bcl2 and blocking proteolytic the cleavage of Caspase-3 in heat stressed-BMECs. Importantly, NMN treatment could reduce mitochondrial damage through mediating the expression of mitochondrial fission and fusion-related genes, including Dynamin related protein 1 (Drp1), Mitochondrial fission 1 protein (Fis1), and Mitofusin1, 2 (MFN1, 2); and suppress endoplasmic reticulum stress through unfolded protein response regulator Glucose regulated protein 78 (GRP78), and downstream elements Recombinant activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). Above all, our results demonstrate that NMN supplemention attenuates heat stress-induced oxidative stress and apoptosis in BMECs by maintaining mitochondrial fission and fusion, and regulating endoplasmic reticulum stress, which provides the convincing evidence that NMN has valuable potential in alleviating mammary gland injury of dairy cows caused by environmental heat stress.

Effects of sex and wet-bulb globe temperature on heart rate variability during prolonged moderate-intensity exercise: a secondary analysis.

Sex differences in heart rate (HR) and heart rate variability (HRV), a surrogate of cardiac autonomic modulation, are evident during rest and exercise in young healthy individuals. However, it remains unclear whether sex impacts HRV during prolonged exercise at differing levels of environmental heat stress. Therefore, we completed a secondary analysis upon the effects of sex and wet-bulb globe temperature (WBGT) on HR and HRV during prolonged exercise. To achieve this, HR and HRV were assessed in non-endurance-trained and non-heat-acclimatised healthy men (n=19) and women (n=15) aged 18-45 years during 180min of treadmill walking at a moderate metabolic rate (200W/m2: equivalent to ∼35% peak aerobic power) in 16, 24, 28, and 32°C WBGT. In the final 5min prior to exercise termination, HR was observed to be higher in women relative to men in all but the 32 °C WBGT. Although no sex differences were observed for the HRV metric of root-mean-square of successive differences, high-frequency power was higher in women relative to men across WBGT conditions. These findings indicate that, in healthy non-heat-acclimatised individuals, women respond to prolonged exercise-heat stress with a greater increase in HR despite cardiac vagal autonomic modulation remaining equal or increasing compared to men. Novelty: Prior to exercise termination, females respond with a greater increase in HR under all WBGTs except the hottest (32 °C). Sexinfluenced HRV metrics during all WBGTs, but results were mixed. Further characterisation of HRV sex differences remains an important area of research.

The application of ascorbic acid as a therapeutic feed additive to boost immunity and antioxidant activity of poultry in heat stress environment.

Ascorbic acid, widely known as vtamin C, is an essential nutrient for animals such as poultry. Ascorbic acid in poultry feed improves animal health and thus increases the growth performance of birds. Ascorbic acid can be used in the form of synthetic products or can be naturally obtained from fruits and plants. It is soluble in water and can be easily administered in drinking water and the diet. Poultry can synthesize ascorbic acid in the body. However, the performance of the animals can be improved by adding ascorbic acid to their diet. In addition, ascorbic acid is called an antioxidant and an anti-inflammatory. This increases their resistance to disease during the transition season. Ascorbic acid supplementation positively affects the stress response, especially during the dry season in tropical countries. Furthermore, supplementing ascorbic acid in the poultry’s diet improves resistance to diseases, regulates stress, and helps in the body’s oxidation process. Ultimately, this enhances the laying rate, egg hatch performance, and higher poultry productivity. For layers at the end of the laying period, it helps increase the quality of the eggshell and reduces the proportion of broken eggs. Ascorbic acid has a strong relationship with other vitamins such as vitamin E and other substances such as zinc, safflower oil, folic acid, and a fibrous diet. This review aims to synthesize all the information of ascorbic acid in the poultry’s diet, thereby providing the general role of ascorbic acid for the poultry industry.

Effects of hypohydration and fluid balance in athletes’ cognitive performance: a systematic review

Background: The effects of progressive body fluid loss on athletic and cognitive performance are known to result from exposure to environmental heat stress, morphologic factors, and limited fluid replenishment. Athletes need to restore lost body water. However, athletes may fail to maintain euhydration during exercise. This systematic review investigated hypohydration and fluid balance effects on an athlete’s cognitive function.&#x0D; Methods: The PubMed, Sports Discuss, and Ebsco databases were searched for studies reporting on hypohydration, fluid balance and heat on cognitive performance in sport. Multiple phrases including hydration, dehydration, fluid balance, mood, cognition, vigilance, decision making, and brain were explored. Participants in the studies did either receive fluid or did not receive fluid during exercise.&#x0D; Results: Twenty-four trials (n=493 participants) from 24 articles met the inclusion criteria. Significant hypohydration, &gt;2% body mass loss was reported consistently in 16 publications. Five articles where hypohydration was associated with heat stress and limited fluid intake (3-5% body mass loss) impaired cognitive performance. Mood disturbance, fatigue, and ratings of perceived exertion constantly complemented hypohydration impairment on cognition.&#x0D; Conclusion: Findings show that hypohydration impairs cognitive performance and mood at higher levels of 3-5% body mass loss. However, sport-specific cognitive protocols of accessing hypohydration and fluid balance in individual and team sports remain equivocal.&#x0D; Keywords: Hypohydration; cognition; mood; fluid replenishment.

Effect of Heat Stress, Dietary Electrolytes, and Vitamins E and C on Growth Performance and Blood Biochemistry of the Broiler Chicken

Environmental heat stress creates a detriment to the welfare and performance in broiler chickens. While there are some dietary mineral and vitamin supplements that mitigate this condition, a rapid, plasma-based detection method would improve management response and broaden the scientific understanding of heat stress. A total of 960 broilers were used to determine the effect of heat stress and dietary electrolyte balance on blood biochemistry. Sex sorted chicks were allocated to 48 pens with 20 chicks per pen creating 6 treatments (3 diets x 2 house environments) with eight replicates and fed one of three dietary treatments: a control containing primarily sodium chloride (NaCl), a heat stress formulation containing bicarbonate (NaHCO3), or heat stress fortified with 200 ppm vitamin C and E (NaHCO3 Fortified). Birds were housed in two different temperature-controlled environments either a thermoneutral (Control) or heat stressed (Heat Stress) environment. At day 28, 35 and 42 venous blood was collected and analyzed using rapid detection methods followed by post-mortem veterinary evaluations. Performance was measured at weekly intervals. Mortality was significantly higher in broilers exposed to heat stress as compared to thermoneutral, while broilers that received dietary sodium chloride also had higher mortality than bicarbonate fed birds. Heat stress significantly impacted potassium, hematocrit, uric acid, total protein, globulin, hematocrit, lymphocytes, sodium, and glucose. This study demonstrates that blood biochemistry of broiler chickens is influenced by dietary intervention and changing environmental conditions. This pattern suggests a blood biomarker footprint of sub-optimal nutrition or poor environmental conditions that may provide valuable information into physiological changes in response to dietary electrolytes, vitamins, and heat stress. Furthermore, this footprint may potentiate the development of diagnostic tools, combining biomarkers to determine nutrition and health status of individual broiler flocks, for nutritionists, veterinarians, and live production managers to manage flocks for environmental, humane, and productive purposes.

Plants utilise ancient conserved peptide upstream open reading frames in stress-responsive translational regulation.

The regulation of protein synthesis plays an important role in the growth and development of all organisms. Upstream open reading frames (uORFs) are commonly found in eukaryotic messenger RNA transcripts and typically attenuate the translation of associated downstream main ORFs (mORFs). Conserved peptide uORFs (CPuORFs) are a rare subset of uORFs, some of which have been shown to conditionally regulate translation by ribosome stalling. Here, we show that Arabidopsis CPuORF19, CPuORF46 and CPuORF47, which are ancient in origin, regulate translation of any downstream ORF, in response to the agriculturally significant environmental signals, heat stress and water limitation. Consequently, these CPuORFs represent a versatile toolkit for inducible gene expression with broad applications. Finally, we note that different classes of CPuORFs may operate during distinct phases of translation, which has implications for the bioengineering of these regulatory factors.

Consequences of Thermal Induced Radiation from Ovens on the Physiology of Bakery Workers in Calabar, Cross Rivers State, Nigeria

Consequences of thermal induced radiation from ovens on the physiology of Bakery workers in Calabar, was investigated. An in-situ measurement approach to estimate the impact of thermal radiation on human physiological changes. The relationships between the measured temperature parameters were correlated with a questionnaire inventory. Statistical analysis of the questionnaires based on the relevant hypotheses was carried out. The results show that, the P-values of 0.005; 0.001; 0.006; 0.001 and 0.001 less than 0.05 in all cases and was prevalent. The statistical result implies that there is a significant effect of thermal radiation emanating from bakery ovens on the physiology of workers as this was used to establish the wellbeing of workers in the perceived heat stressed environment. It also was found out that the exposure of workers to thermal radiation in all the bakeries under study exceeded the WHO (20oC- 29oC) exposure limit for comfort. All the bakeries visited during this study used firewood industrial oven.

Intensive masculinization caused by chronic heat stress in juvenile Cynoglossus semilaevis: Growth performance, gonadal histology and gene responses

The sea temperature has been observed to chronically increase during the past decades, leaving unpredictable influences to the marine biological resources. Thus, it is of vital significance to study the biological responses of ocean inhabited organisms with the artificially stimulated heat stress environment. Cynoglossus semilaevis provides us with an ideal model to study the influence of chronic heat stress on the sexual differentiation in marine teleosts for its genetic sex determination (GSD) + environmental effected (EE) sex determination system. In this study, the comparative experiment was conducted employing heated seawater (HT group) and ambient seawater (CT group) to cultivate juvenile C. semilaevis respectively. Significant differences were exhibited in growth performance and a delayed germ cell development effect was found in pseudomales formed under chronic heat stress. Using transcriptome analysis, the transcription profile of 55 days post fertilization (dpf) and 100 dpf juveniles’ gonads were studied. A total of 47 libraries were constructed with an average mapping rate of 94.63% after assembling. GO and KEGG enrichment were proceeded using DEGs screened out between (1) pseudomale gonads at 55 dpf and 100 dpf in HT and CT group (2) pseudomale and female gonads at 55 dpf and 100 dpf in HT and CT group. Terms and pathways involved in steroid stimulation, reproduction ability, germ cell proliferation et al. were shed light on. The expression pattern of 29 DEGs including amh, hsp90b1, pgr et al. were also provided to supplement the results of functional enrichment. Weighted gene co-expression networks analysis (WGCNA) was constructed and hspb8-like, histone H2A.V were exhibited to play vital roles in the heat-induced masculinization. Our findings facilitate the understanding for transcriptional variations in intensive masculinization cause by chronic heat stress of C. semilaevis and provide referable study of the influences on the teleosts in elevated sea temperature.