Effects Of Heat Stress Research Articles

Asynchronous effects of heat stress on growth rates of massive corals and damselfish in the Red Sea.

Climate change is imposing multiple stressors on marine life, leading to a restructuring of ecological communities as species exhibit differential sensitivities to these stressors. With the ocean warming and wind patterns shifting, processes that drive thermal variations in coastal regions, such as marine heatwaves and upwelling events, can change in frequency, timing, duration, and severity. These changes in environmental parameters can physiologically impact organisms residing in these habitats. Here, we investigate the synchrony of coral and reef fish responses to environmental disturbance in the Red Sea, including an unprecedented combination of heat stress and upwelling that led to mass coral bleaching in 2015. We developed cross-dated growth chronologies from otoliths of 156 individuals of two planktivorous damselfish species, Pomacentrus sulfureus and Amblyglyphidodon flavilatus, and from skeletal cores of 48 Porites spp. coral colonies. During and immediately after the 2015 upwelling and bleaching event, damselfishes exhibited a positive growth anomaly but corals displayed reduced growth. Yet, after 2015-2016, these patterns were reversed with damselfishes showing a decline in growth and corals rebounding to pre-disturbance growth rates. Our results reveal an asynchronous response between corals and reef fish, with corals succumbing to the direct effects of heat stress, and then quickly recovering when the heat stress subsided-at least, for those corals that survived the bleaching event. Conversely, damselfish growth temporarily benefited from the events of 2015, potentially due to the increased metabolic demand from increased temperature and increased food supply from the upwelling event, before declining over four years, possibly related to indirect effects associated with habitat degradation following coral mortality. Overall, our study highlights the increasingly complex, often asynchronous, ecological ramifications of climate extremes on the diverse species assemblages of coral reefs.

Effect of Short Duration Heat Stress on the Physiological and Production Parameters of Holstein-Friesian Crossbred Dairy Cows in Bangladesh

Heat stress is a major concern for lactating dairy cows. This study evaluated the effects of heat stress on six Holstein-Friesian crossbred dairy cows exposed to three thermal conditions represented by the Temperature-Humidity Index (THI). These conditions included a baseline pre-treatment phase at THI-72, a heat stress treatment phase at THI-75 and THI-80, and a post-treatment recovery phase at THI-72. The duration of the heat stress treatment phase was 24 h. A total of four trials, each involving three cows, were conducted in an IoT-based climatic chamber to assess various physiological, hematological, biochemical, and production parameters across these phases. Compared to the baseline (THI-72), cows showed significant increases (p < 0.05) in rectal temperature (RT), heart rate (HR), respiration rate (RR), and water intake (WI) at both THI-75 and THI-80, with the highest elevations observed at THI-80 (RT: 5.1%, HR: 8.6%, RR: 23.5%, and WI: 19.1%). Feed intake declined significantly (p < 0.05) by 6.5% and 14.0%, and milk yield dropped by 5.3% and 14.7% at THI-75 and THI-80, respectively; milk fat and protein percentages decreased by 1.1-fold and 1.2-fold. Hemoglobin, platelet, and lymphocyte counts, along with biochemical parameters (excluding serum creatinine) also decreased significantly (p < 0.05). The different levels of THI influenced pairwise correlation patterns, with THI-75 showing intense interactions and THI-80 exhibiting greater variability. The findings highlight that Holstein-Friesian crossbreed dairy cows are particularly vulnerable to heat stress, even with short-term exposure. This vulnerability can lead to economic losses for Bangladeshi dairy farmers rearing Holstein-Friesian crossbreed cows.

Using Microalgae as a Good Motivator of Ossimi Lamb's Health and Growth

ABSTRACTIn tropical and subtropical countries like Egypt, sheep breeding faces environmental thermal stress, especially during the summer when air temperature and humidity are very high. Using Microalgae as an alternative feedstuff can significantly improve sheep growth, health and oxidative status. Therefore, this study aimed to evaluate the effect of consuming two different species of microalgae: Spirulina platensis (SP) and Chlorella vulgaris (C. vulgaris) on the following: growth performance, oxidative status, kidney and liver function, serum Glu, proteins and lipids profile and haematological parameters under hot dry environmental conditions. A total of 32 Ossimi male lambs were divided randomly into four equal groups (n = 8), (G1) was fed the control diet, (G2) was supplemented with S. platensis, (G3) was supplemented with a combination between (S. platensis and C. vulgaris) and (G4) was supplemented C. vulgaris. The results of our study revealed that microalgae supplementation significantly (p ≤ 0.05) enhanced lamb's growth, liver and kidney function, levels of serum immunoglobulin IgG, glutathione peroxidase (GPX) and haematological parameters. Moreover, the levels of thyroid hormones and serum proteins profile were significantly increased in all treated lambs compared to the control group. Our research revealed that including microalgae in sheep's feed can enhance their immune system, promote growth and enhance their general health by mitigating the harmful effects of heat and oxidative stress.

Adverse effects of heat stress and the benefits of using phytase in Japanese quail (coturnix japonica) diets – A review

Adverse effects of heat stress and the benefits of using phytase in Japanese quail (coturnix japonica) diets – A review

Effect of maternal heat stress at different stages of pregnancy on the reproductive performance and antral follicle count of the progeny of Holstein cows

The objective was to evaluate the effect of maternal exposure to heat stress conditions at different stages of pregnancy on the reproductive performance and antral follicle count of progeny. The study was conducted at five commercial dairy farms located in southeastern Brazil. Retrospective data (2002 and 2015) on reproductive indices of daughters of Holstein cows that were exposed to heat stress conditions in the first (n = 447), second (n = 729) or third (n = 746) trimester of pregnancy and daughters of cows not exposed to heat stress (n = 359) were analyzed. Antral follicle count (AFC) and ovarian size were determined in a subgroup of animals (n = 242) by transrectal ultrasound. Statistical analysis was performed using the SAS GLIMMIX procedure. The number of services after first calving was lower in daughters of cows not exposed to heat stress conditions than in those exposed during different trimesters of pregnancy (P = 0.03). The calving interval was longer for daughters of cows exposed to heat stress conditions in the second and third trimesters of pregnancy than for those not exposed to heat stress (P = 0.01). In addition, the probability of pregnancy at first AI, (P = 0.01) and the AFC (P = 0.001) were greater in daughters of cows not exposed to heat stress conditions than in those exposed during the different phases of the gestational period. These findings indicate that maternal heat stress in different stages of pregnancy negatively affect the future fertility and AFC of bovine offspring.

Effect of Heat and Drought Stress on the Growth of Selected Grass Species of Pothohar Region

Effect of Heat and Drought Stress on the Growth of Selected Grass Species of Pothohar Region

Modeling the effects of heat stress on production and enteric methane emission in high-yielding dairy herds.

Given global warming and the growing dairy population, heat stress in dairy herds is of increasing concern. During heat stress, dairy cows suffer from compromised productivity and animal welfare in terms of reduced feed intake and milk production, decreased reproductive performance, and generally increased risk of health problems. These effects and their interactions are complex and are usually quantified separately, and thereby a comprehensive understanding of the herd-level performance is missing. Moreover, compromised animal welfare and productivity may impact enteric methane (CH4) emission, however, these effects have rarely been investigated. Therefore, by performing herd simulation, this study aimed to model the impact of heat stress on dairy production and enteric CH4 emission by aggregating its effects on milk production, reproduction, and health. Specifically, 10 scenarios (including baseline) were simulated in a conventional, high-yielding Danish herd by incorporating different combinations of effects on milk production, reproduction, and health of heat stress in different exposure durations (1, 2, and 4 mo). Sensitivity analyses were further conducted to account for the effects of different reduction rates in feed efficiency (kg ECM/kg DMI). Results showed that heat stress decreased the herd-level milk yield by up to 8.6% if all effects were combined in a duration of 4 mo, whereas a direct effect on milk yield only decreased herd-level yield by up to 6.9%. Heat stress increased the herd-level enteric CH4 intensity ranging from 0.8 to 6.6% across all 9 scenarios as compared with the baseline scenario. When a reduction in feed efficiency by 19.2% was assumed, the herd-level CH4 intensity increased by up to 4.4% during 2 mo. Overall, our results showed large impacts of heat stress on both dairy production and CH4 emission and suggest the need to implement management mitigation strategies in heat-stressed dairy herds.

New insights into the neurophysiological effects of heat stress on the Chinese mitten crab (Eriocheir sinensis)

New insights into the neurophysiological effects of heat stress on the Chinese mitten crab (Eriocheir sinensis)

Acute heat stress regulates estradiol synthesis in ovine ovarian granulosa cells through the SREBPs/MVK–LHR pathway

The adverse effects of heat stress on reproductive performance of sheep are becoming increasingly severe. Previous research has revealed that heat stress decreases both cholesterol and estradiol content; however, regulation of estradiol by cholesterol and its regulatory mechanism under heat stress are unclear. Mevalonate kinase (MVK), a key cholesterol synthesis pathway enzyme, binds to the luteinizing hormone receptor (LHR; a key gene regulating hormone synthesis) mRNA. In this study, ovine ovarian granulosa cells (GCs) were used in an in vitro model. To elucidate the underlying molecular mechanism, immunofluorescence, quantitative reverse transcription polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, and an RNA electrophoretic mobility shift assay (REMSA) were used to investigate whether the decrease in cholesterol caused by acute heat stress resulted in a decrease in estradiol synthesis. Acute heat stress reduced the cholesterol content in ovine ovarian GCs, which transactivated the cholesterol synthesis pathway corresponding to the gene expression of sterol regulatory element-binding protein (SREBP-1A), SREBP-2, and MVK. Upregulated MVK increased the MVK–LHR mRNA complex, which caused LHR mRNA decay and downregulation, further leading to the downregulation of CYP19A1 and a decrease in estradiol. The cholesterol synthesis inhibitor, PF-429242, alleviated the decrease in estradiol synthesis caused by acute heat stress. Overall, acute heat stress caused a decrease in total cholesterol, which transactivated the expression of cholesterol synthesis genes, such as SREBP-1A, SREBP2, and MVK, increasing the MVK–LHR complex, downregulating LHR expression, and further decreasing estradiol.

Scientific knowledge about gene expression in ruminants under heat stress - A scientometric review.

Heat stress can alter the expression of genes in the individual's molecular response. The identification of these genes makes it possible to better understand the molecular response, identifying biomarker genes and indirect response pathways that can help with genetic improvement studies, animal welfare, separating more thermotolerant varieties and mitigating the effects of heat stress. The aim of this scientometric review was to characterize the state of the art of scientific research into gene expression in ruminants under heat stress, to define the most studied species, biology systems and genes, as well as the related biological pathways and processes. The articles for the dataset were compiled in the Web of Science database, refined individually and analyzed using the CiteSpace, RStudio, Excel and GraphPad Prism programs and the KEGG (Kyoto Encyclopedia of Genes and Genomes) database. The publications formed a data set containing 271 articles and an H-index of 37. The number of publications increased from 2011. The countries with the highest frequency of publications are India, the United States, China and Brazil, the ruminant species are cattle, buffaloes, sheep and goats, all zootechnical interest, and biology systems was reproduction, blood and lactation, due to the economic importance of the quality and quantity of production, to the ease of collecting and possibility of studies in vitro. Cattle have been extensively studied in comparison to other ruminants. The HSP70 gene has been the most studied, followed by the HSP family, HSF, BAX, TLR and BCL-2, these genes can be molecular markers of heat stress. The main pathways and biological processes of genes were in cattle the cancer pathway; in goats the Mixed, incl. myd88-dependent toll-like receptor signaling pathway, and lipopolys; in sheep the oxidoreductase; and in buffalo it was the BCL-2 family. The molecular responses are still recent and have not been established.

A systematic review on the trend of transcriptomic study in livestock: An effort to unwind the complexity of adaptation in a climate change environment.

Heat stress has been proven to cause negative effects on livestock leading to lower productivity and economic value. Understanding how heat stress manifests within an animal's body is the first step in devising a heat stress mitigation strategy; transcriptomic studies are one of the methods used. Here, using a systematic literature review methodology, we examine the recent decade of transcriptomics' application to the study of livestock adaptation. We identified 152 studies that met our criteria for using transcriptome methods to heat stress adaptation and were published within the last ten years. Our analysis demonstrates the growing popularity and application of transcriptome approaches in the investigation of the response of ruminants, pigs, and poultry livestock to heat stress. Majority of the works was done in chicken and cattle using multiple organs as the sample, with qRT-PCR as the most employed technique. It has been established that a variety of biomarkers can be used to assess animals under heat stress, such as the HSPs, ILs, and TLRs. Although transcriptomics has lately been employed extensively to uncover the mechanism of heat adaptation, this adaptive feature's complex mechanism remains unclear, leaving many knowledge gaps for investigation. A more complex studies involving more various cell types, organs, or even model organisms using multi-omics approach could be the future research direction in understanding the heat stress effects on livestock better.

Unravelling the photosynthetic dynamics and fluorescence parameters under ameliorative effects of 24-epibrassinolide in wheat (Triticum aestivum L.) grown under heat stress regime

An experiment was performed at the Banaras Hindu University, India to study the effect of terminal heat stress on photosynthetic dynamics and fluorescence parameters of wheat genotypes and ameliorative effects of epibrassinolide by taking two genotypes with four concentrations as foliar spray at two growth stages of wheat. The highest values were observed in plots foliar sprayed with 1.0 µM 24-epibrassinolide (T1) under normal conditions (D1) where the genotype Sonalika (V1) performed significantly well w.r.t. the parameters viz. steady-state fluorescence (Fs) 116.22, quantum efficiency of PSII 0.59, maximum fluorescence (Fm) 776.5, normalized stress detection ratio (Fv/Fo) 4.47, maximum potential quantum efficiency of PSII (Fv/Fm) 0.82.Whereas under heat stress condition (late sown D2), there was significant reduction in these parameters in both the genotypes which was improved by the application of epibrassinolide suggesting its potential role in improving the photoinhibition process by raising the efficiency of PSII. Overall, the calibrated application of 24-epibrassinolide was found to be a potent growth regulator involved in the positive modulation of heat stress tolerance in wheat, coupled with improved photosynthetic efficiency in treated plots as compared to control.

Responses of Poultry to Heat Stress and Mitigation Strategies During Summer in Tropical Countries: A Review<b></b>

The poultry industry faces increasing challenges from heat stress caused by global warming, particularly in tropical regions. Heat stress, caused by rising environmental temperatures, undermines the health and productivity of poultry, resulting in significant economic losses. This review comprehensively addresses the physiological and behavioural responses of poultry to heat stress and explores the key mitigation strategies, categorized under genetics, management and feeding. Genetic approaches, like utilizing specific genes in breeding, show promise but require wider adoption. Management practices such as housing design, including orientation, insulation and ventilation, controlled lighting and thermal manipulation are critical to maintaining poultry in their thermoneutral zone. Furthermore, feeding strategies like feed restriction, dual feeding and nutritional manipulation have shown promise in reducing heat stress effects. In addition to feeding strategies, water management is also crucial for mitigating heat stress, especially in tropical areas. Ensuring sufficient water space, maintaining operating waterers, and keeping water cool are essential to encourage adequate drinking. Despite progress, further investigation is required to explore the synergistic effects of combined strategies to improve the resilience of poultry. This review highlights the urgent need for comprehensive approaches to mitigate heat stress in poultry to ensure sustainable productivity under the challenges of global warming

The effects of acute operational stress and passive heat stress on physiological and subjective stress responses in military personnel.

Military personnel often encounter situations that can trigger acute stress, which may affect operational performance. Therefore, it is important to examine stress responses in controlled environments to obtain more insights in performance-influencing effects of acute stress. This study investigated the impact of passive heat exposure combined with virtual combat scenarios on cardiovascular and psychophysiological parameters in a controlled setting. Sixty-eight healthy servicemembers were randomized into a low-stress or high-stress condition. Both groups engaged in two virtual combat scenarios. The low-stress group, however, underwent testing under thermoneutral conditions (MTemp = 22.4 °C, MRelativeHumidity = 41.4 %) whereas the high-stress group was exposed to passive heat exposure (MTemp = 35.9 °C, MRelativeHumidity = 66.4 %) using a portable environmental facility. While virtual combat scenarios alone led to a decrease in heart rate variability (HRV) without affecting heart rate (HR), the addition of passive heat exposure elicited a more pronounced physiological stress response, characterized by significantly higher HR and lower HRV in the high-stress condition. However, no significant changes were observed in respiratory rate, salivary cortisol, or alpha-amylase levels across the conditions, suggesting that there was no activation of either the hypothalamic-pituitary-adrenal or the sympathetic-adrenal-medullary axis. Furthermore, subjective stress and anxiety scores did not differ between conditions, underscoring the physiological nature of the observed changes. Resultantly, the physiological response was likely a thermal reaction rather than an acute stress response. These findings highlight the importance of incorporating environmental stressors into military training protocols to enhance realism and prepare personnel for operational stressors. However, the mild response observed suggests that higher ambient temperatures and longer exposure times may be necessary to evoke a more robust stress response for effective stress inoculation training.

Time series (ARIMA) as a tool to predict the temperature-humidity index in the dairy region of the northern desert of Mexico.

The environment in which an animal is situated can have a profound impact on its health, welfare, and productivity. This phenomenon is particularly evident in the case of dairy cattle, then, in order to quantify the impact of ambient temperature (°C) and the relative humidity (%) on dairy cattle, the temperature-humidity index (THI) is employed as a metric. This indicator enables the practical estimation of the stress imposed on cattle by ambient temperature and humidity. A seasonal autoregressive integrated moving average (SARIMA) (4,1,0)(0,1,0)365 model was estimated using daily data from the maximum daily THI of 4 years (2016-2019) of the Comarca Lagunera, an arid region of central-northern Mexico. The resulting model indicated that the THI of any given day in the area can be estimated based on the THI values of the previous four days. Furthermore, the data demonstrate an annual increase in the number of days the THI indicates a risk of heat stress. It is essential to continue building predictive models to develop effective strategies to mitigate the adverse effects of heat stress in dairy cattle (and other species) in the region.

Effect of heat stress on meat quality of growing rabbits divergently selected for body fat content

High ambient temperature represents an increasingly frequent challenge for animal farming, especially for those animal species more susceptible to heat stress (HS), like the rabbit. The present research studied the impact of different ambient temperatures (T: 20 °C—Control vs. 28 °C—High) on the meat quality of two rabbit lines (L: Fat line, Lean line) obtained after 5 generations of divergent selection for total body fat content. After slaughter, the ground meat of 60 carcases (15 rabbits/treatment) was used for physicochemical and sensory quality evaluation. Overall, high T affected hind leg weight (p < 0.001), pHu (p = 0.001), and oxidative status (p = 0.004) during a shelf-life trial. High T increased meat haem-iron (p < 0.001), decreased lipids (p < 0.001), MUFA (p < 0.001), and PUFA classes (p < 0.001), and consequently, increased water content (p < 0.001). Regarding L effect, Fat line was richer in lipids (p < 0.001) and ash (p = 0.008), but less rich in water (p < 0.001) than Lean line. The content of all fatty acid (FA) classes was therefore significantly higher in Fat line meat (p < 0.001). It can be concluded that the two genotypes differed for proximate composition, haem-iron, FA, and amino acid profiles of carcase meat. High T increased meat pHu, water, haem-iron, and reduced polyunsaturated FA (PUFA) amount. At high T the meat of the Fat line showed higher TBARS, whereas Lean line had higher lysine content. Sensory analysis revealed that high T improved tenderness and extinguished onion off-flavour.

The kidney under heat stress: a vulnerable state.

This review examines the effects of occupational heat stress on kidney health. It focuses on the role of hyperthermia in the development of acute kidney injury (AKI) and its potential progression to chronic kidney disease of nontraditional etiology (CKDnt). We highlight the physiological mechanisms by which hyperthermia affects kidney function and discuss emerging preventive strategies. Hyperthermia places the kidneys in a vulnerable state. As body temperature increases, blood flow is directed toward the skin to aid in cooling, diverting it away from internal organs like the kidneys to support blood pressure regulation. At the same time, hyperthermia and dehydration increases energetic demand to promote fluid and electrolyte conservation. Collectively, this can create a localized supply-demand mismatch, resulting in tissue hypoxia that can damage kidney tissues. These findings highlight that heat hyperthermia can lead to subclinical kidney damage, with potential long-term implications for kidney health. Heat-induced AKI is a growing public health concern. Individuals engaged in manual labor with prolonged exposure are at risk of CKDnt. Interventions aimed to prevent hyperthermia show promise in mitigating the risk of AKI. Further research is necessary to refine these strategies and establish evidence-based guidelines for reducing heat-related kidney injuries.

The heat sensitivity of sperm in the lizard Anolis sagrei.

The heat sensitivity of reproduction is a critical determinant of population persistence under climate change. However, the heat sensitivity of gametes has been much less studied relative to that of adults. We developed a method to measure the heat tolerance limits of lizard sperm cells, and used the method to test several aspects of sperm cell thermal biology in the brown anole lizard (Anolis sagrei). We estimated the repeatability of sperm traits by measuring heat tolerance and baseline motility of ejaculated sperm from the same individuals multiple times over 21 days. To investigate co-adaptation of sperm and adult thermal traits, we tested for a correlation between sperm heat tolerance and the heat tolerance of adults that produced them. Furthermore, we tested for effects of episodic heat stress experienced by males on sperm performance. Sperm heat tolerance and motility were both repeatable, consistent with evolutionary potential, though there was clear evidence for environmental effects on these traits as well. Contrary to the expectation of thermal co-adaptation, we found no correlation between sperm and adult heat tolerance. A single, episodic extreme heat event experienced by adult males immediately impaired sperm motility, consistent with detrimental effects of adult heat stress on sperm stored within males. Our study adds to the mounting evidence that sperm are heat-sensitive and represent a vulnerability to global warming, but also suggest evolutionary potential for thermal adaptation at the gamete level.

203 Effects of prenatal heat stress on subsequent reproductive outcomes in replacement Holstein heifers up to the first lactation

203 Effects of prenatal heat stress on subsequent reproductive outcomes in replacement Holstein heifers up to the first lactation

178 The effects of heat stress on the number of ovarian follicles in the dairy cow

178 The effects of heat stress on the number of ovarian follicles in the dairy cow