Environmental Heat Stress Research Articles

Physiological and Yield Responses of Indian Mustard (Brassica juncea) to Terminal Heat Stress

In present investigation we studied the influence of terminal heat stress on several agronomic, physiological and yield-related variables in 10 mustard genotypes; Advance-414, Anmol, Bond, Coral-432, JKMS 8532, MRR-8030, NMS-2018, Rajshree, RH-30 and Sonalika. The experiment conducted under control condition (Sown in October) and heat stressed environment (Sown in November) to assess the role of ambient and high temperatures, respectively. Different characteristics including relative water content (RWC), water saturation deficit (WSD), relative dry weight (RDW), membrane stability index (MSI), days to flowering, plant height and yield attributes were analysed in respect to heat stress. The results demonstrated strong relationship between genotype and treatment in responses to heat stress. In terms of RWC, RH-30 maintained high value in both normal (95.17 ± 0.991%) and late sown (72.78 ± 1.022%) circumstances, but Coral-432 showed sensitivity to stress conditions with reduction in relative water content ranging from 80.91±0.085% in control environment to 51.30±0.988% in late sown condition. Heat stress significantly raised water saturation deficit in all genotypes, with RH-30 retaining lower WSD (4.83 ± 0.083%; control and 27.22±0.595% heat stress) than Coral-432 (19.08 ± 0.467% control and 48.70 ± 0.179% heat stress) whereas membrane stability index ranged from 5.03 ± 0.033% to18.03 ± 0.176%. Yield attributes such as seed yield per plant, test weight drastically reduced under heat stress whereas, genotype RH-30 showed resistance to stress and highest in seed yield (14.22 ± 0.215 g) and 1000-seed weight (test weight; 4.35 ± 0.066 g) under stress. Plant height and number of branches also showed similar reduction in respect to heat stress. Overall, genotypes RH-30 and Rajshree found superior to stress tolerance in all tested parameters and further used in the breeding programme to develop the heat resilience cultivar in mustard.

Parent-Specific Transgenerational Immune Priming Enhances Offspring Defense-Unless Heat Stress Negates It All.

Transgenerational immune priming (TGIP) adjusts offspring's immune responses based on parental immunological experiences. It is predicted to be adaptive when parent-offspring environmental conditions match, while mismatches negate those advantages, rendering TGIP potentially costly. We tested these cost-benefit dynamics in the pipefish Syngnathus typhle (Syngnathidae). Because of their unique male pregnancy, egg production and rearing occur in different sexes, providing both parents multiple avenues for TGIP. Parental bacteria exposure in our pipefish was simulated through vaccinations with heat-killed Vibrio aestuarianus before mating the fish to each other or to controls. The resulting offspring were exposed to V. aestuarianus in control or heat stress environments, after which transcriptome and microbiome compositions were investigated. Transcriptomic TGIP effects were only observed in Vibrio-exposed offspring at control temperatures, arguing for low costs of TGIP in non-matching microbiota environments. Transcriptomic phenotypes elicited by maternal and paternal TGIP had limited overlap and were not additive. Parentally induced transcriptomic responses were associated with immune functions, and specifically, the paternal response to the innate immune branch, possibly hinting at trained immunity. TGIP of both parents reduced the relative abundance of the experimental Vibrio in exposed offspring, showcasing its ecological benefits. Despite TGIP's significance in matching biotic environments, no TGIP-associated phenotypes were observed for heat-treated offspring, illustrating its limitations. Heat spikes caused by climate change thus threaten TGIP benefits, potentially increasing susceptibility to emerging marine diseases. We demonstrate the urgent need to understand how animals cope with climate-induced changes in microbial assemblages to assess their vulnerability in light of climate change.

Environmental Heat Stress Detrimentally Affects Match Running Performance of Elite Soccer Teams Competing in the UEFA Champions League.

Modric, T, Clemente, FM, Versic, S, Chmura, P, Andrzejewski, M, Kryściak, J, and Sekulic, D. Environmental heat stress detrimentally affects match running performance of elite soccer teams competing in the UEFA Champions League. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to examine the effect of environmental heat stress (EHS), defined by wet-bulb globe temperature (WBGT), on match running performance (MRP) while controlling for match-related contextual factors. For this purpose, 2 approaches were implemented: (a) the MRP in heat stress nonrisking environment (NoEHS) (WBGT <22° C) and heat stress risking environment (EHSrisk) (WBGT ≥22° C) were compared and (b) changes in MRP according to the 1° C increase in WBGT were evaluated. Data on MRP were collected using an optical tracking system from all teams ( n = 32) in all UEFA Champions League matches ( n = 125) during the 2022-23 season. Metrics included total distance (TD), low-intensity (LIR), moderate-intensity (MIR), and high-intensity running (HIR) distances. Results indicated that less TD (108.84 vs. 110.71 km; Cohen's d [ d ] = 0.53), MIR (15.91 vs. 17.09 km; d = 0.85), and HIR (8.75 vs. 9.23 km; d = 0.46) were covered in matches played in EHSrisk compared with the NoEHS. Further investigation indicated that for every 1° C increase in WBGT, TD averagely decreased by 0.16 km ( d = -0.48), MIR by 0.13 km ( d = -1.09), and HIR by 0.06 km ( d = -0.69). These findings demonstrated decreased overall and intensive workload during the matches in EHSrisk, suggesting the detrimental effect of EHS on match volume and intensity in elite soccer. When EHS risk is anticipated, consideration of playing and recovery strategies should be implemented by coaches to achieve tactical goals while minimizing physical strain during a match.

Administration of melatonin nanoparticles improves testicular blood flow, echotexture of testicular parenchyma, scrotal circumference, and levels of estradiol and nitric oxide in prepubertal ossimi rams under summer heat stress.

Environmental heat stress (HS) impairs reproductive efficiency in farm animals. This study investigated, for the first time, how the melatonin and melatonin nanoparticles treatment affected the testicular hemodynamics, testicular volume, echotexture [Pixel intensity (PIX) and integrated density (IND)], scrotal circumference, serum concentration of testosterone (T), estradiol (E2), nitric oxide (NO), and total antioxidant capacity (TAC) in prepubertal Ossimi ram lambs in hot climatic conditions. The lambs undergoing examination had a temperature humidity index (THI) of 87.05 ± 1.70, indicating severe HS condition. Fifteen prepubertal Ossimi ram lambs were exposed to a single s.c injection of either nano melatonin (nano melatonin group; 20mg/ram; n = 5) or melatonin suspended in two ml of corn oil (melatonin group; 40mg/ram; n = 5) or two ml of corn oil (control group; n = 5). Blood collection and ultrasonographic assessment of the testes and supratesticular arteries (STAs) were conducted immediately before treatment (W0) and once weekly for six successive weeks after nano melatonin and melatonin injection (W1-W6). Results revealed decreases (P < 0.05) in the Doppler indices (resistive index; RI and pulsatility index; PI) of the testicular arteries at most time points of the study in the nano melatonin and melatonin groups. PIX of testicular parenchyma was significantly increased (P ˂ 0.05) in the treated groups compared to the control one. IND of testicular parenchyma increased significantly in the nano melatonin group compared to the melatonin and control groups. Testicular volume and scrotal circumference significantly increased (P < 0.05) in nano melatonin and melatonin groups compared to the control one. T concentration did not significantly (P > 0.05) change in the treated groups compared to the control group. E2, NO, and TAC concentrations increased (P < 0.05) in the treated groups compared to the control one. In conclusion, this study extrapolated that administrations of melatonin or nano melatonin can ameliorate the effects of environmental HS in prepubertal Ossimi ram lambs with a more protective effect and lower dose of nano melatonin.

Integrating observational and modelled data to advance the understanding of heat stress effects on pregnant subsistence farmers in the gambia

Studies on the effect of heat stress on pregnant women are scarce, particularly in highly vulnerable populations. To support the risk assessment of pregnant subsistence farmers in the West Kiang district, The Gambia we conducted a study on the pathophysiological effects of extreme heat stress and assessed the applicability of heat stress indices. From ERA5 climate reanalysis we added location-specific modelled solar radiation to datasets of a previous observational cohort study involving on-site measurements of 92 women working in the heat. Associations between physiological and environmental variables were assessed through Pearson correlation coefficient analysis, mixed effect linear models with random intercepts per participant and confirmatory composite analysis. We found Pearson correlations between r-values of 0 and 0.54, as well as independent effects of environmental variables on skin- and tympanic temperature, but not on heart rate, within a confidence interval of 98%. Pregnant women experienced stronger pathophysiological effects from heat stress in their third rather than in their second trimester. Environmental heat stress significantly altered maternal heat strain, particularly under humid conditions above a 50% relative humidity threshold, demonstrating interactive effects. Based on our results, we recommend including heat stress indices (e.g. UTCI or WBGT) in local heat-health warning systems.

Genetics of Exertional Heat Illness: Revealing New Associations and Expanding Heterogeneity

Environmental heat stress represents a pervasive threat to warfighters, athletes, and occupational workers, impacting performance and increasing the risk of injury. Exertional heat illness (EHI) is a spectrum of clinical disorders of increasing severity. While frequently predictable, EHI can occur unexpectedly and may be followed by long-term comorbidities, including cardiovascular dysfunction and exercise intolerance. The objective of this study was to assess genetic factors contributing to EHI. Whole-exome sequencing was performed in a cohort of 53 cases diagnosed with EHI. Rare variants in prioritized gene sets were analyzed and classified per published guidelines. Clinically significant pathogenic and potentially pathogenic variants were identified in 30.2% of the study cohort. Variants were found in 14 genes, including the previously known RYR1 and ACADVL genes and 12 other genes (CAPN3, MYH7, PFKM, RYR2, TRPM4, and genes for mitochondrial disorders) reported here for the first time in EHI. Supporting structural and functional studies of the TRPM4 p.Arg905Trp variant show that it impairs the thermal sensitivity of the TRPM4 channel, revealing a potentially new molecular mechanism contributing to EHI susceptibility. Our study demonstrates associations between EHI and genes implicated in muscle disorders, cardiomyopathies, thermoregulation, and oxidative phosphorylation deficiencies. These results expand the genetic heterogeneity of EHI and shed light on its molecular pathogenesis.

Environmental Heat Stress Decreases Sperm Motility by Disrupting the Diurnal Rhythms of Rumen Microbes and Metabolites in Hu Rams.

Heat stress (HS) has become a common stressor, owing to the increasing frequency of extreme high-temperature weather triggered by global warming, which has seriously affected the reproductive capacity of important livestock such as sheep. However, little is known about whether HS reduces sperm motility by inducing circadian rhythm disorders in rumen microorganisms and metabolites in sheep. In this study, the year-round reproduction of two-year-old Hu rams was selected, and the samples were collected in May and July 2022 at average environmental temperatures between 18.71 °C and 33.58 °C, respectively. The experiment revealed that the mean temperature-humidity index was 86.34 in July, indicating that Hu rams suffered from HS. Our research revealed that HS significantly decreased sperm motility in Hu rams. Microbiome analysis further revealed that HS reshaped the composition and circadian rhythm of rumen microorganisms, leading to the circadian disruption of microorganisms that drive cortisol and testosterone synthesis. Serum indicators further confirmed that HS significantly increased the concentrations of cortisol during the daytime and decreased the testosterone concentration at the highest body temperature. Untargeted metabolomics analysis revealed that the circadian rhythm of rumen fluid metabolites in the HS group was enriched by the cortisol and steroid synthesis pathways. Moreover, HS downregulated metabolites, such as kaempferol and L-tryptophan in rumen fluid and seminal plasma, which are associated with promotion of spermatogenesis and sperm motility; furthermore, these metabolites were found to be strongly positively correlated with Veillonellaceae_UCG_001. Overall, this study revealed the relationship between the HS-induced circadian rhythm disruption of rumen microorganisms and metabolites and sperm motility decline. Our findings provide a new perspective for further interventions in enhancing sheep sperm motility with regard to the circadian time scale.

Potential benefits of advanced chelate-based trace minerals in improving bone mineralization, antioxidant status, immunity, and gene expression modulation in heat-stressed broilers.

Organic sources of trace minerals (TM) in broiler diets are more bioavailable and stable than inorganic sources, making them particularly beneficial during challenging periods such as heat stress (HS) conditions. A 42-d study investigated the effects of using advanced chelate technology-based TM (ACTM) or adding varying amounts of ACTM to broiler diets during HS conditions. The study involved 672 male broiler chickens in 7 treatment groups, including a thermoneutral control (TNC) group and six HS treatments. There were 8 replicate pens per treatment and 12 birds per replicate. The six HS treatments included birds exposed to a cyclic HS environment (34°C) for 8 h and were as follows: HSC, which consisted of the same basal diet with the recommended ITM levels; ACTM50 and ACTM100, which replaced the basal diet with 50% and 100% ACTM instead of ITM; ITM+ACTM12.5 and ITM+ACTM25, which involved adding extra ACTM to the ITM basal diet at 12.5% and 25%, respectively; and ITM125, which used 125% of the recommended levels of ITM in the basal diet. Compared with the HSC treatment, the TNC, ACTM100, and ITM+ACTM25 treatments resulted in increased (P < 0.05) body weight; tibia weight; tibia ash, phosphorus, iron, and manganese contents; secondary antibody titers; and serum TAC and SOD values but decreased (P < 0.05) serum MDA concentrations and the expression levels of the hepatic genes IL-1β, IL-6, and INF-γ. The TNC and ACTM100 groups also showed greater (P < 0.05) feed efficiency, tibia length, tibia zinc content, and hepatic SOD1 expression but exhibited reduced (P < 0.05) hepatic NF-kB expression. Significant increases (P < 0.05) in primary anti-NDV titers, serum GPx1 activity, and Nrf2 and GPx1 gene expression levels were also detected in the ACTM100, ITM+ACTM12.5, and ITM+ACTM25 groups. In conclusion, the findings suggest that replacing ITM with ACTM or adding ACTM to ITM diets, especially at a 25% higher dose, can effectively protect broilers from heat stress by promoting growth, reducing inflammation, and increasing the expression of antioxidant proteins.

Evaluation of the extent of genetic variability and associated traits of bread wheat (Triticum aestivum L.) genotypes under heat and drought stress environment conditions

Evaluation of the extent of genetic variability and associated traits of bread wheat (Triticum aestivum L.) genotypes under heat and drought stress environment conditions

Inheritance Analysis for Quantitative Traits in F2 Populations of Mustard Genotypes Grown Under Heat Stress Environments

Genetic variability is the basic requirement for improving crops which further leads to progress in crop breeding. This study was carried out to determine the inheritance pattern of various agronomically important traits in F2 populations of mustard genotypes. The objective of this study was to determine the genetic variability for agro-morphological traits under control conditions (CC) and heat stress environments (HS) and provide the future strategies to improve this important oilseed crop. The experiment was conducted at the Botanical Garden, Sindh Agriculture University, Tandojam. During 2022-23, a total of 27 genotypes including nine parental mustard genotypes and eighteen F2 progenies were grown under control and heat stress conditions. The experiment was laid out in a randomized complete block design with three replications. The analysis of variance for the genotypes, treatments, and F2 progenies revealed significant differences (P≤0.05) in most of the studied characters, highlighting the importance of genetic variations in the evaluated breeding materials of mustard for stress breeding. When estimating heritability for different characters, including seed yield plant-1, it was found that F2 crosses showed varying levels of heritability for different characteristics, ranging from low to moderate and high. This implies that careful selection may be conducted for traits that have low heritability, especially for seed yield.; however, those characters which showed high heritability would be selected at early generation stage to improve the characters.

Climate change impacts on livestock in Brazil

Brazilian livestock provides a significant fraction of the food consumed globally, making the country one of the largest producers and exporters of meat, milk and eggs. However, current advances in the production of protein from Brazilian animal origin may be directly impacted by climate change and the resulting biophysical effects. Therefore, it is strategically consistent to develop measures to deal with the resulting environmental heat stress on domesticated animal species, especially the need in developing countries. This work aims to (1) evaluate the impacts of climate change on livestock (cattle-dairy, cattle-beef, goats, sheep, pigs, poultry-general) in different regions of Brazil and (2) discuss possible response strategies, associated with animal comfort and welfare. From our results, we can draw better strategies to mitigate the impacts of climate change on livestock production. The results presented show an increase of high heat stress in South and Southeast and an increase of extreme heat stress in North and Central-West areas of Brazil. The rise in extreme heat stress tends to occur mostly during spring and summer and tends to vary considering the different evaluated species. Within the evaluated species, the ones that seem to be more affected by climate changes are Poultry, pigs, cattle-beef and general (temperature-humidity index value). The differences between the results for the five geographic regions in Brazil suggests that different mitigation measures need to be considered to cope with future heat stress in livestock. To ensure the long-term success of Brazil's influence on the global market for proteins of animal origin, it must achieve sustainable production systems more intensively.

Estimation of Heritability, Genetic Advance and Correlation in Bread Wheat (Triticum aesitvum L.) under Heat Stress Condition

The current study was conducted on several genotypes during crop season of Rabi 2021-2022 and 2022-2023 with the goal of to work out heritability in general and genetic advance in percentage of mean and estimate correlation coefficient among the growth and yield traits. The field experiments included 60 germplasms of bread wheat. Experimental trials were conducted in 12 environments (E1 to E12). The field experiments were laid out in Augmented Block Design (ABD). The observations on 26 physio-morphological and yield related traits were recorded in both non-stressed and heat-stressed environment. High genotypic and phenotypic coefficients of variation were observed for plant waxiness (8.897 and 11.943) followed by leaf rolling (6.390 and 12.240). Heritability coupled with genetic advance were identified in yield per plot (g), grain yield / plant (g), plant waxiness (0-10 scale). Grain yield per plant exhibited significant positive correlation with grain length (0.712), harvest index (0.629), leaf rolling (0.4638). It exhibited significant negative correlation with plant height (-0.461) and canopy temperature depression (-0.233).

Feed additives supplementation: a potential strategy to ameliorate heat stress in sheep

Abstract Given a significant climate-flexible and socio-economic role in developing nations, environmental heat stress imposes a major financial impact on sheep production systems globally endangering their production, reproduction, and growth. In this regard, the adverse effects of heat stress on sheep production systems have to be addressed through adoption of effective heat alleviation measures like animal management, nutritional management and genetic interventions of which the nutritional interventions seems to be the most cost effective way to alleviate heat stress. Nutritional manipulation for heat stress alleviation in sheep involves the use of antioxidant supplements (Vitamin B; Vitamin E and Selenium; Selenium; Zinc sulphate and folic acid; Vitamin C, Vitamin E, Selenium and Zinc; Naringin; Opuntia ficus-indica f. inermis; Açai oil and Brown seaweed like Ascophyllum nodosum and Sargassum latifolium). Further, electrolyte supplements (Dietary Electrolyte Balance (DEB); Sodium bicarbonate and potassium bicarbonate; Sodium hydroxide) have a beneficial effect on thermal responses, respiratory activities, gas exchange parameters, rumen fermentation, blood buffering capacity and acid-base balance. The mineral mixture supplements (Mineral blocks; Mineral mixture and antioxidants; Chromium; Zinc) play a crucial role in increasing the efficiency of antioxidant defence system, immunity-related parameters, production, reproduction, feed digestibility and insulin sensitivity. Probiotic supplements (Lactobacillus acidophilus, Saccharomyces cervisiae, Propionibacterium freudenreichii, Lactobacillus casei, Enterococcus faecium, Lactobacillus lactis, Bacillus subtilis, Propionibacterium freudenreichii, Pediococcus cerevisiae, Megaspha eraelsdenii, Bacillus licheniformis, Aspergillus oryzae, Schizochytrium limacinum, Trichoderma reesei and Saccharomyces cerevisiae) improve lactational performance, dietary energy utilization and productivity. The probiotics (live Saccharomyces cerevisiae) and prebiotics (mannan oligosaccharide plus b-glucans) used in heat stress alleviation improve dietary energy utilisation. Furthermore, the vital role of herbal supplements (Rosemary, Cinnamon, Turmeric, Clove, Naringin, Chestnut tannins, Giloy stem powder, Curcumin, Rocket oil (watercress oil), Flaxseed, Cornus, Oregano, Thyme, Chamomile flowers, Moringa oleifera, Betaine) has been highlighted to promote feed intake, antioxidant status, growth performance, feed utilization, reproductive performance and immune response. Effective adoption of nutritional strategies can thus ensure sustainable sheep production in this changing climate scenario.

Genotypic Selection Using Quantitative Trait Loci for Better Productivity under High Temperature Stress in Tomato (Solanum lycopersicum L.)

High temperature stress affects tomato production both in tropical and sub-tropical environments worldwide. To explore genetic variation for heat tolerance in tomato, 329 transcontinental tomato genotypes were evaluated at the Ministry of Municipality and Environment (MME) greenhouses near Doha, Qatar, where the average daytime temperature was 38 °C with a big fluctuation during the tomato growth season. A preliminary phenotypic analysis identified a panel of 71 hybrid and pure-line tomato genotypes for more detailed studies. The selected subset was examined in the greenhouse using a randomized complete block design under heat stress. The materials were phenotyped for fruit size, fruit weight, fruit hardness, fruit locules, fruit set, total soluble solids (TSS), and fruit yield. Significant phenotypic differences among genotypes were observed for all the traits assessed. To explore the genetic basis of the variation among the examined genotypes, the subset was genotyped using 104 SNP markers identified in previous heat-tolerance genome-wide association studies (GWAS). Nineteen QTL-associated SNP markers could reliably select heat-tolerant genotypes in terms of better fruit yield, fruit set, and TSS. These markers are located on chromosome 1, 5, 6, 8, 9, and 12. Interestingly, two clusters of markers on chromosome 6 were linked to significant effects on yield, fruit set, and TSS under high temperature. Eighteen out of nineteen SNP markers were mapped within a gene body. Based on the phenotypic and the genotypic analysis, an elite set of five genotypes was selected for approval for heat stress environments in Qatar. The aim of the present work is to provide significant results that are exploitable not only in the Qatar region but also worldwide. Specifically, the 19 molecular markers identified in this study can serve as useful tools for breeders in selecting heat-tolerant material.

Genetic Evaluation of Heterosis and Combining Ability of Quality Protein Maize (Zea mays L.) Hybrids under Terminal Heat Stress Conditions

Background: The development of quality protein maize (QPM) hybrids tolerant to terminal stress environments has been an essential strategy for reducing the associated loss in grain yield. A study by Badu-Apraku et al., (2019) employed line × tester analysis in QPM breeding, highlighting its efficacy in selecting QPM hybrids. While QPM varieties resistant to disease, drought and environmental stresses have been developed conventionally, the adoption of improved QPM genotypes in farmers’ field is restricted mainly due to lack of proper team effort among maize breeders, farmers, agricultural extension workers and other relevant stakeholders. Methods: In line × tester mating design, six lines and three testers were crossed under heat stress environment and 18 F1s along with parental lines were evaluated along with check varietal during summer season, 2023, P.G research farm, CUTM, Paralakhemudi, Odisha. The objective of the current study was to evaluate parental lines and its crosses based on combining ability and heterosis. Result: ANOVA revealed significant to revealed significant differences for all the traits between parents, lines, testers and lines vs testers, except for cob height, chlorophyll content and canopy temperature. 𝛔2GCA/𝛔2SCA values for parents/hybrids recorded lower than unity for all the trait studied suggesting preponderance of non-additive gene action. Parental lines CML149, CML143 and CML330 are the best general combiners for early flowering, grain yield per plant and antioxidant status. Among eighteen crosses, two hybrids CML149 × CML330 and CML143 × CML193 recorded significant SCA effects for early flowering, grain yield per plant and antioxidant levels. Hybrids CML149 × CML330 (33.31%) and CML143 × CML193 (28.31%) noted significant standard heterosis for grain yield per plant over commercial check, HQPM-1. Hybrids CML149 × CML330 and CML143 × CML193 were resilient to terminal heat stress as they didn’t exhibit signs of leaf firing, tassel blast, root lodging and loss of yield.

Genome-Wide Identification and Characterization of U-Box Gene Family Members and Analysis of Their Expression Patterns in Phaseolus vulgaris L. under Cold Stress.

The common bean (Phaseolus vulgaris L.) is an economically important food crop grown worldwide; however, its production is affected by various environmental stresses, including cold, heat, and drought stress. The plant U-box (PUB) protein family participates in various biological processes and stress responses, but the gene function and expression patterns of its members in the common bean remain unclear. Here, we systematically identified 63 U-box genes, including 8 tandem genes and 55 non-tandem genes, in the common bean. These PvPUB genes were unevenly distributed across 11 chromosomes, with chromosome 2 holding the most members of the PUB family, containing 10 PUB genes. The analysis of the phylogenetic tree classified the 63 PUB genes into three groups. Moreover, transcriptome analysis based on cold-tolerant and cold-sensitive varieties identified 4 differentially expressed PvPUB genes, suggesting their roles in cold tolerance. Taken together, this study serves as a valuable resource for exploring the functional aspects of the common bean U-box gene family and offers crucial theoretical support for the development of new cold-tolerant common bean varieties.

Effects of heat stress on endocrine, thermoregulatory, and lactation capacity in heat-tolerant and -sensitive dry cows.

Increasing global temperatures present a significant challenge to livestock production. The dry period is an important stage in the production cycle of cow, and environmental heat stress (HS) during this period can have adverse effects on the subsequent lactation performance. In this study, we aimed to investigate the effects of HS on endocrine, thermoregulatory, and lactation parameters in heat-tolerant dry cows (HTDC) and heat-sensitive dry cows (HSDC). We measured the respiratory rate (RR), body temperature (BT), and temperature-humidity index (THI) in 66 dry cows during HS. The slopes of RR and BT to THI were determined through analysis of measurements and dry cows background information using a mixed-effects model. Subsequently, the heat tolerance or sensitivity of dry cows was assessed using clustering method (HTDC = 19 and HSDC = 47). Compared with that of HSDC, the RR of HTDC significantly increased after exposure to HS (p < 0.05). The average reduction in milk yield from new lactation to the previous lactation was significantly lower in HTDC compared to HSDC (p < 0.05). Plasma cortisol and non-esterified fatty acid levels were significantly lower in HTDC compared to HSDC (p < 0.05), while plasma triiodothyronine (p = 0.07) and growth hormone (p = 0.08) levels tended to be higher in HTDC relative to HSDC. HTDC can more effectively alleviate the impacts of HS through their superior thermoregulation and metabolism, thereby ensuring optimal postpartum lactation performance.

Understanding the physiological and biological response to ambient heat exposure in pregnancy: protocol for a systematic review and meta-analysis

IntroductionClimate change increases not only the frequency, intensity and duration of extreme heat events but also annual temperatures globally, resulting in many negative health effects, including harmful effects on pregnancy...

Melatonin modulates behavioral and oxidative stress responses in donkeys (Equus asinus) subjected to packing during hot-dry conditions

The aim of the study was to evaluate the effects of melatonin administration on oxidative stress and behavioral responses immediately (1-h) post-packing and 16-h post-packing circadian rhythms in donkeys during hot-dry conditions. Twenty healthy pack donkeys (15 males and five non-pregnant females), aged 2–3 years with average weight of 93 ± 2.7 kg were divided into two groups randomly. Melatonin was administered at a dose of 10 mg per donkey for 7 days to group 1 donkeys (packing + melatonin) that were subjected to packing (load-carrying), group 2 (packing–melatonin) donkeys were packed only without melatonin administration. The donkeys trekked covering 20 km, three times during the one week experiment, one day apart. Meteorological parameters were recorded during the study period. Serum harvested from the blood sample collected from each donkey before and after packing was analysed for oxidative stress biomarkers. Behavioral parameters were evaluated using the focal animal sampling technique for 1 h immediately (1-h) after packing and at expiration of 16-h post-packing, covering 27-h period at 3-h intervals. Melatonin reduced oxidative stress by preventing reduction in catalase activity and total antioxidant capacity in packing + melatonin donkeys. Melatonin exerted anti-stress effects on behavioral activities in the treated donkeys post-packing by significantly reducing (P < 0.05) the percent duration of grooming, walking and standing, but significantly increasing (P < 0.05) the percent duration of feeding, compared to the control donkeys. In conclusion, melatonin exerted beneficial effects against stresses due to packing and heat, and influenced the circadian rhythms of behavioral activities. Its administration may reduce the risk of negative effects of environmental heat stress and stress due to packing in donkeys during hot-dry conditions.

Functional oil in the feeding of heat-stressed Japanese quail

The objective of the present study was to evaluate a blend of functional oils (FO) composed of copaiba and garlic essential oils, pepper oleoresin and cashew nut liquid to mitigate the effects of heat stress on productivity, egg quality, organ morphology of the gastrointestinal tract, serum biochemical profile, nutrient metabolism and body temperature of Japanese quail. A completely randomized design was used in a 3 × 2 factorial scheme (without additive; 300 and 500 mg FO/kg of feed x birds raised in a thermal comfort (TC) and heat stress (HS) environment), with 6 replicates of 8 birds per plot. The birds under HS had lower feed intake (P = 0.0000), egg mass (P = 0.0000), laying rate (P = 0.0000) and higher percentage of infertile non-commercial eggs (P = 0.0004), lower head temperature amplitude (P = 0.0000) and higher average of body temperature (P = 0.0312). HS worsened the external and internal quality of the eggs. Birds kept in HS showed higher values of cholesterol (P = 0.0000) and glutamic-pyruvic transaminase (P = 0.0272). The use of 300 and 500 g FO/ton of feed improved the feed conversion (P = 0.0000) and egg mass (P = 0.0000) of the quail bred under HS, respectively, by 8.4 and 7.2% and increased the relative weight of liver (P = 0.0064) and pancreas (P = 0.0492). The use of such additives also provided a higher % of yolk (P = 0.0018) and reduced the percentage of albumen (P = 0.0029) of the eggs produced in TC, in addition to reducing the amplitude of head temperature (P = 0.0484) of birds bred under HS. The breeding of Japanese quail under HS results in negative impacts on the production, physiological and qualitative aspects of the eggs. The use of 300 g/ton of FO in the diet of Japanese quail leads to improvements in feed conversion, increased liver capacity in nutritional metabolism and results in eggs with a higher proportion of yolks, being, therefore, an alternative for feeding quail in a hot climate.