Mitigate Heat Stress Research Articles

Shade effect on behaviour, physiology, performance, and carcass weight of heat-stressed feedlot steers in humid subtropical area

Context Environmental conditions during hot weather decrease feed intake and cattle growth. Aims This study conducted over three consecutive years, during the summer, evaluated access to shade as a strategy to mitigate heat stress of finishing cattle in Uruguay. Methods Each year, 32 Bos taurus and/or Bos taurus crossbred steers (initially weighing 461 ± 28 kg) were blocked by initial liveweight and assigned to one of eight pens, where one of two treatments were applied, namely, no shade access or shade access (mean shaded area 4.5 m2/animal). Finishing diet was offered three times per day and cattle had ad libitum access to water. Twenty-four pens were considered in a randomised complete-block design. Average daily gain (ADG), dry matter intake (DMI) and feed efficiency were measured, and hot carcass weight was collected at slaughter. Ruminal pH and temperature were obtained using ruminal boluses. Feeding, drinking, rumination, inactive behaviours, respiration rate and painting score were observed. Key results Mean days on feed were 70.6 ± 5.5. The average THI ranged from 70 to 72. Steers with access to shade had greater DMI (P = 0.003), ADG (P = 0.004), and feed:gain ratio (P = 0.05) than did not shaded steers. Ruminal pH was higher (P < 0.0001) in shaded than in not shaded animals. The slaughter weight of shaded steers was 10 kg greater (P = 0.02) than that of not shaded steers. A trend (P = 0.06) to higher hot carcass weight after dressing was obtained by shaded steers. The average respiration rate and panting score was consistently lower (P < 0.0001) for shaded than for not shaded steers, except in the early morning. Access to shade increased the time spent by animals feeding (P = 0.008) and ruminating (P = 0.001), decreasing inactive time (P < 0.0001). Conclusions Shade could improve performance and welfare of feedlot cattle during summertime, even in regions with an average THI from 70 to 72. Implications Access to shade allowed fattening cattle to dissipate heat stored during the day at night and to alleviate the effect of heat load during summer in subtropical region.

Chia Polyphenols as Dietary Supplement: A Sustainable Strategy to Mitigate Heat Stress in Japanese Quail

Chia Polyphenols as Dietary Supplement: A Sustainable Strategy to Mitigate Heat Stress in Japanese Quail

Research, development and adoption for the north Australian beef cattle breeding industry: an analysis of needs and gaps

This review seeks to analyse and prioritise needs and gaps in research and development (R&D) for the north Australian beef cattle breeding industry, and to advise on options to increase rates of adoption and successful implementation of this R&D. The material reviewed includes the peer-reviewed literature as well as industry reports and other relevant publications in three targeted areas of R&D deemed to be important by industry leaders and supporting scientists: (i) breeding herd management, (ii) feedbase management, and (iii) management of environmental sustainability. For breeding herd management, the need for uniform definition and consistent utilisation of appropriate productivity metrics is highlighted, with emphasis on assessment of maternal reproductive efficiency in terms of weaning (or branding) rates. Priority is given to the urgent need for reliable means of remotely assessing causes of neonatal calf mortality to enable the development and application of management interventions that improve calf survival rates. The highest priority for feedbase management is to increase producer awareness and willingness to adopt stocking rates that are appropriately matched to the long-term carrying capacity of native rangeland pastures that predominate in northern Australia. Other opportunities include increasing the use of perennial, tropically adapted legumes, where conditions permit, to improve soil fertility and nitrogen intake of cattle, and devising strategies to overcome widespread phosphorus deficiency through diagnosis and supplementation, especially in the wet season. In order to enhance environmental sustainability in the face of climate change, priorities include improving producer awareness and use of increasingly robust tools for predicting key weather events, as well as developing genetic strategies to increase heat tolerance of cattle and evaluating management interventions to mitigate heat stress. Conclusions drawn from these sections are summarised and used to make recommendations on priorities for increasing adoption of existing research-proven practices and technologies, and for further R&D on selected topics.

Occupational Heat Stress in the Floriculture Industry of Ethiopia: Health Risks and Productivity Losses

Background: The Ethiopian flower industry is growing fast with successful diversification of export products under greenhouse structures. Higher temperatures in the greenhouses pose a serious threat to the health of workers and add to the risk of occupational heat stress. Excessive heat in workplace settings also reduces work capacity and labour productivity. This study aims to investigate the level of heat exposure, and workers’ and managers’ perceptions and behavioural responses towards extreme heat exposure in a warming climate. Methods: We used the Wet Bulb Globe Temperature (WBGT) measured in representative greenhouses to capture the heat exposure during hotter and cooler seasons following ISO 7243 (generally risk of heat stress occurs when WBGT exceeds 26°C). A comparative cross-sectional study design with a stratified sampling method was used to assess occupational heat stress and workers’ perceptions of the impact of heat on their health and productivity in six different floriculture greenhouses in Ethiopia representing three different agro-ecologies and products. A questionnaire survey was conducted (30 managers/supervisors and 305 workers; 76.1% female) to capture perceptions on heat exposures, symptoms of potential health impacts, productivity losses and coping mechanisms. Results: Heat exposure varied across different agroecologies, product types and greenhouse materials with a median WBGT Index of 25.5°C and a range from 18.1°C to 31.5°C. The impact of heat stress also varied across different employment sectors and geographical regions. Overall, workers in cut-flower greenhouses are exposed to higher than recommended WBGT Index (26°C) for 3 - 6 working hours daily. 65% of the managers reported that heat stress has a significant impact on the workers’ labour productivity, but do not have guidance about working in hot conditions. Workers reported more heat-related health issues and reduced productivity, especially in the mid-altitude greenhouses. About 50% of the workers reported that heat exposure decreased work productivity during hot hours. Sweating, exhaustion, heat-rashes, dehydration, crumps, nausea and headache were self-reported health issues. Labour productivity losses ranged from no loss to 19.5% in the mid- and low-altitudes. Conclusions and Recommendations: Excessive workplace heat in the greenhouses is both an occupational health hazard and detrimental to productivity in the floriculture industry. However, the level of understanding and actions on the ground regarding occupational heat stress are low. The code of conduct in place now does not consider the occupational heat stress issues. Multiple actions (engineering, management, training and policy-related recommendations) have to be implemented by Ethiopian Horticultural Producers and Exporters Association (EHPEA) and farm owners to mitigate heat stress and loss of productivity. Designing and implementing these heat prevention strategies and incorporating them into the code of conduct is in the interests of both employers and employees.

Mitigação do estresse térmico na germinação e desenvolvimento inicial de plântulas de cenoura por meio de reguladores de crescimento vegetal

ABSTRACT The adoption of technologies that allow the mitigation of environmental stresses, such as the use of regulators in seed treatment, is an alternative for crops in high temperatures regions. This study aimed to assess the heat stress mitigation on the germination and initial development of carrot seedlings using plant growth regulators. The study was divided into three experiments performed at the temperatures of 25, 30 and 35 °C. A 5 × 3 factorial arrangement was used, with fve carrot cultivars (Alvorada, Brasília, BRS Esplanada, Tellus and Tropical) and two products (Stimulate® and thiamethoxam), in addition to the control (untreated seeds). The following variables were evaluated: germination, first germination count, seedling length and dry mass. When the cultivars had their seeds treated with the plant growth regulators at 25 °C, the germination for the Tellus cultivar was 28 % higher than for the control, while, at 30 °C, the seed germination for BRS Esplanada and Tellus was twice as high as for the control, and showed a higher vigor than that of Alvorada, Brasília and Tropical. Overall, the thiamethoxam promoted increments at the initial development of carrot seedlings at 25 and 30 °C. However, the germination of the carrot cultivars was disrupted at 35 °C.

Characterizing the effect of incrementally increasing dry bulb temperature on linear and nonlinear measures of heart rate variability in nonpregnant, mid-gestation, and late-gestation sows.

Characterizing the sow physiological response to an increased heat load is essential for effective heat stress mitigation. The study objective was to characterize the effects of a 400-min heating episode on sow heart rate variability (HRV) at different reproductive stages. HRV is a commonly used noninvasive proxy measure of autonomic function. Twenty-seven sows were enrolled in the study according to their gestation stage at time of selection: 1) nonpregnant (NP; n = 7), 2) mid-gestation (MID; 57.3±11.8 d gestation; n = 11), and 3) late-gestation (LATE; 98.8±4.9 d gestation; n = 8). The HRV data utilized in the study were collected from each pig as the dry bulb temperature in the room increased incrementally from 19.84±2.15 °C to 35.54±0.43 °C (range: 17.1-37.5 °C) over a 400-min period. After data collection, one 5-min set of continuous heart rate data were identified per pig for each of nine temperature intervals (19-20.99, 21-22.99, 23-24.99, 25-26.99, 27-28.99, 29-30.99, 31-32.99, 33-34.99, and 35-36.99 °C). Mean inter-beat interval length (RR), standard deviation of r-r intervals (SDNN), root mean square of successive differences (RMSSD), high frequency spectral power (HF), sample entropy (SampEn), short-term detrended fluctuation analysis (DFAα1), and three measures (%REC, DET, LMEAN) derived from recurrence quantification analysis were calculated for each data set. All data were analyzed using the PROC GLIMMIX procedure in SAS 9.4. Overall, LATE sows exhibited lower RR than NP sows (P < 0.01). The standard deviation of r-r intervals and RMSSD differed between each group (P < 0.01), with LATE sows exhibiting the lowest SDNN and RMSSD and NP sows exhibiting the greatest SDNN and RMSSD. Late-gestation sows exhibited lower HF than both MID and NP sows (P < 0.0001), greater DFA values than NP sows (P = 0.05), and greater DET compared to MID sows (P = 0.001). Late-gestation also sows exhibited greater %REC and LMEAN compared to MID (P < 0.01) and NP sows (all P < 0.01). In conclusion, LATE sows exhibited indicators of greater autonomic stress throughout the heating period compared to MID and NP sows. However, temperature by treatment interactions were not detected as dry bulb increased. Future studies are needed to fully elucidate the effect of gestational stage and increasing dry bulb temperature on sow HRV.

UV Parasol, Dry-Mist Spraying, and Street Trees as Tools for Heat Stress Mitigation

UV Parasol, Dry-Mist Spraying, and Street Trees as Tools for Heat Stress Mitigation

A comprehensive genome-wide scan detects genomic regions related to local adaptation and climate resilience in Mediterranean domestic sheep

BackgroundThe management of farm animal genetic resources and the adaptation of animals to climate change will probably have major effects on the long-term sustainability of the livestock sector. Genomic data harbour useful relevant information that needs to be harnessed for effectively managing genetic resources. In this paper, we report the genome characterization of the highly productive Mediterranean Chios dairy sheep and focus on genetic diversity measures related with local adaptation and selection and the genetic architecture of animal resilience to weather fluctuations as a novel adaptative trait linked to climate change.ResultsWe detected runs of homozygosity (ROH) and heterozygosity (ROHet) that revealed multiple highly homozygous and heterozygous hotspots across the Chios sheep genome. A particularly highly homozygous region was identified on chromosome 13 as a candidate of directional genetic selection associated with milk traits, which includes annotated genes that were previously shown to be linked to local adaptation to harsh environmental conditions. Favourable heterozygosity related with a potentially protective role against livestock diseases and enhanced overall fitness was revealed in heterozygous-rich regions on sheep chromosomes 3, 10, 13 and 19. Furthermore, genomic analyses were conducted on sheep resilience phenotypes that display changes in milk production in response to weather variation. Sheep resilience to heat stress was a significantly heritable trait (h2 = 0.26) and genetically antagonistic to milk production. Genome-wide association and regional heritability mapping analyses revealed novel genomic markers and regions on chromosome 5 that were significantly associated with sheep resilience to climate change. Subsequently, an annotation analysis detected a set of genes on chromosome 5 that were associated with olfactory receptor complexes that could participate in heat stress mitigation through changes in respiration rate and respiratory evaporation. Other genes were grouped in previously reported biological processes relevant to livestock heat dissipation, including stress and immune response.ConclusionsOur results may contribute to the optimal management of sheep genetic resources and inform modern selective breeding programmes that aim at mitigating future environmental challenges towards sustainable farming, while better balancing animal adaptation and productivity. Our results are directly relevant to the studied breed and the respective environmental conditions; however, the methodology may be extended to other livestock species of interest.

Heat Stress Mitigation with Fogging System of Anatolian Water Buffaloes

This research was carried out to investigate the possibilities of removing the heat stress that may occur in Anatolian water buffaloes with a fogging system and to determine the cooling efficiency of the system. In this context, two 24-headed groups were formed among the water buffaloes that were considered to have the same genetic similarities, were born in the same period and have the same lactation number. One group was housed under controlled shelter conditions (Shelter-I), where the ambient temperature can be controlled, and the other group was housed in existing farmer-raising conditions (Shelter-II). The same feed rations were applied to both buffalo groups. The cooling efficiency of the fogging system established in Shelter-I was between 45.6% and 85.7% positive. Temperature-Humidity Index values changed between 19.9 and 23.1 in Shelter-I and 19.5 and 26.4 in Shelter-II according to the maximum average data. According to these values, the level of stress in Shelter-II has reached very serious levels and affected the milk yield of buffaloes negatively. The corrected 305-day lactation milk yields were calculated as 1965.4 kg in Shelter-I and 1757.1 kg in Shelter-II. The differences between all data obtained for Shelter-I and Shelter-II were found statistically significant.

Automated Monitoring of Cattle Heat Stress and Its Mitigation

Climate change related global warming is likely to continue, despite all mitigation measures taken by humans, due to the lag effect of long-term anthropogenic activities. Warming of the atmosphere can impact worldwide cattle production directly by compromising health, welfare and productivity, and indirectly by reducing the quality and quantity of animal feed. Under warm thermal conditions, cattle adjust their physiological and behavioural responses as an integral part of thermoregulation to maintain internal body temperature within a safe range. However, a greater intensity and duration of heat exposure can exceed thermoregulatory capacity leading to an increase in internal body temperature beyond the normal limit that ultimately evokes different animal responses to heat. In cattle, response to heat stress can be visually observed as elevated respiration rate or panting, but continuous visual monitoring is labour intensive, time consuming and subjective. Therefore, different weather-based indices have been developed such as the temperature humidity index (THI) and heat load index (HLI) which are commonly used weather-based indices for monitoring cattle heat stress at commercial level. However, the thermal comfort level of cattle based on weather-based indices has limited use at a microclimatic and individual animal level. Varying sensor-based approaches have shown promise to shift the focus of heat stress management to the individual level. Monitoring individual animal response and mitigation strategies for isolated heat-susceptible cattle could save on heat management costs whilst improving animal welfare and productivity. Here we review the technologies that enable automatic, continuous, and real-time cattle heat stress monitoring and mitigation under commercial conditions. Future platforms for autonomous monitoring and mitigation of heat stress in cattle are likely to be based on minimally-invasive smart technologies either singly, or in an integrated system, enabling real-time solutions to animal responses under various production systems and environmental conditions.

483 Current Knowledge Gaps in Swine Reproduction

Abstract Identifying swine reproduction research opportunities, especially those that add value by addressing industry challenges and leveraging assisted reproductive technologies (ART) will be the focus of this talk. ART and genetic selection to increase pork production efficiency have been intertwined since the use of artificial insemination (AI) became widely adopted 30 years ago. Tremendous efficiency gains have been made in part by increasing litter size which is nearly 6 to 7 pigs larger today than it was in 1990. The increased farrowing duration and stillbirths, and decreased piglet birth weight, colostrum intake, and survival to weaning that has been associated with these larger litters are prime targets to be ameliorated with sow and pig management solutions. There is also clear evidence that pigs from smaller litters have the advantage of superior reproductive performance compared to those from larger litters. Thus, litter size and pre-weaning growth may need to be managed, or at least taken into account, to select the best boars and gilts for breeding stock and replacements. Any other accurate, early indicators of boar and gilt puberty, fertility, and lifetime productivity could add significant value. The seasonal fluctuation in fertility that has plagued pig production is costly and may be smoothed out by strategies that mitigate heat stress and improve health. Another opportunity to improve both pig and sow welfare may be intermittent suckling and induction of a fertile estrus and ovulation for breeding during lactation. Even more genetic and pig growth value could be added via AI with sex-sorted semen, if methods to better estimate boar fertility, deliver increased sperm quality, and more precisely synchronize or predict ovulation can be found to reduce the number of sperm required per female. Existing and evolving ART will synergize with genomics and gene editing technologies to unlock new levels of production efficiency.

275 Access to Shade Mitigate Heat Stress and Improves Growth Performance in Lambs During Summer

Abstract The objective of the present study was to investigate the effects of provision of shade on behavior, physiology, and growth of Merino lambs exposed to natural Australian summer conditions. Sixty Merino lambs were randomly allocated to either pasture with shade (n = 30;paddock with trees) or a pasture without shade (n = 30;paddock without any trees) for one month during southern-Australian summer (February-2021). Sheep were grazing on the pastures as per standard protocols followed on the farm with ad libitum access to water. Lambs were monitored twice daily between 0900-1000h and 1400-1600h to record their behavior, and physiological parameters were recorded on hot days (environmental temperature (T) &amp;gt;30°C). Behavioral patterns were represented as the proportion of animals doing specific activities in each treatment group. Grazing was the most frequent activity observed in animals during morning measurement (&amp;gt; 60% in both groups). However, high temperature (T &amp;gt; 30°C) decreased grazing behavior in sheep to &amp;lt; 5% in both treatments. Standing behavior was significantly greater (65.2 vs 21.6%; P &amp;lt; 0.05) for animals under non-shade treatment, while lying behavior was more frequent (17.3 vs 76.3%; P &amp;lt; 0.01) in animals having access to shade. Significantly more animals were seeking water troughs (P &amp;lt; 0.05) in the non-shade group (33.2%) compared to the shade group (10.3%). On an average hot day (T &amp;gt;28°C), most lambs in the shade group were seeking shade (P &amp;lt; 0.01), and when the temperature exceeded &amp;gt;32°C, 90% of the lambs were seeking tree shade. Sheep with access to shade exhibited lower (P &amp;lt; 0.01) respiration rate (117breaths/min) and rectal temperature (39.7°C) than non-shade group (151breaths/min;40.2°C). Overall, access to shade improved (P &amp;lt; 0.001) average daily gain (+0.047kg/day) in sheep compared to the non-shade group (-0.028kg/day). In conclusion, our research confirms that providing access to shade is an effective ameliorative strategy to mitigate heat-stress in sheep during summer heatwaves.

246 Examining Melatonin-induced Changes in Uterine Blood Flow and Vaginal Temperatures in Nutrient Restricted Pregnant Heifers

Abstract The objectives were to examine melatonin mediated changes in temporal uterine blood flow (UBF) and vaginal temperatures (VT) in 54 Brangus heifers (Fall, n = 29; Summer, n = 25) during compromised pregnancy. At d160 of gestation, heifers were assigned to 1 of 4 groups consisting of adequately fed (ADQ-CON; 100% NRC; n=13), global nutrient restricted (RES-CON; 60% NRC; n = 13), and ADQ or RES supplemented with 20 mg of melatonin (ADQ-MEL, n = 13; RES-MEL, n = 15). In the morning (0500h) and afternoon (1300h) of d220 of gestation, temperature dataloggers (Onset Computer Corporation) attached to progesterone-free CIDRs were used to record VT, while UBF was determined via Doppler ultrasonography. Data were analyzed using repeated measures of ANOVA (SAS). Significant differences were found in UBF and VT between Fall and Summer groups (P&amp;lt; 0.05), therefore seasons were individually analyzed. In Fall, a nutrition by treatment interaction was significant, where the RES-CON heifers exhibited reduced total UBF compared to ADQ-CON (5.67±0.68 vs. 7.97±0.54 L/min; P = 0.012). In Summer, there was not a main effect of nutrition (P = 0.390); nevertheless, the MEL heifers exhibited increased total UBF compared to the CON counterparts (8.16±0.73 vs. 6.00±0.70 L/min; P = 0.048). Moreover, there was a nutrition by treatment by time interaction in VT for Fall and Summer heifers (P &amp;lt; 0.0001). In Fall, all groups had decreased VT in the morning compared to the afternoon (P &amp;lt; 0.0001). Whereas, in Summer, VT increased for ADQ-CON, RES-CON, and ADQ-MEL from morning to afternoon (P &amp;lt; 0.0001), while the RES-MEL remained constant throughout the day (P = 0.649). Furthermore, during the afternoon RES-MEL heifers exhibited decreased VT compared to ADQ-CON (38.91±0.09 vs. 39.26±0.09°C, respectively; P=0.039). In summary, nutrient restriction and melatonin supplementation altered UBF in a season dependent manner. Additionally, with the VT differences observed in Summer, future studies should evaluate the potential of melatonin supplementation for mitigating heat stress in farm animals.

Heat stress mitigation strategies used by midwestern cattle feeders

The objective of this survey was to obtain descriptive data and cattle feeders’ perceptions regarding facilities and heat stress (HS) mitigation strategies. Feedlot managers (n = 46) from South Dakota (SD; n = 21), Minnesota (MN; n = 6), and Nebraska (NE; n = 19) were surveyed regarding facilities, management, and perceptions of HS mitigation strategies. The SD and MN responses were combined (MN/SD) for summarization. Open yards (OY) were the most commonly reported facility, particularly in NE, where OY were reported by 100% of participants and comprised 90% of facility types. Facility types in MN/SD were more diverse, with OY, total barn confinement, and partially covered comprising 49, 30, and 21% of all facility types, respectively. Shades and sprinklers were used in 79 and 100% of NE OY, respectively, compared with 32 and 86% of MN/SD OY, respectively. Feed deliveries were adjusted in summer by 37 and 30% of NE and MN/SD managers, respectively. All respondents avoided unnecessary cattle handling during HS events. Shades or buildings were perceived as successful by 63 and 56% of respondents from NE and MN/SD, respectively, whereas water application was deemed effective by 32 and 63% from NE and MN/SD, respectively. Shades structures were named by 63% of respondents from both regions as the most desirable HS mitigation measure, followed by confinement buildings (16 and 18% for NE and MN/SD, respectively). Midwest cattle feeders use multiple approaches to mitigate HS, with those providing shade deemed most desirable.

Physiological and molecular insights on wheat responses to heat stress.

Increasing temperature is a key component of global climate change, affecting crop growth and productivity worldwide. Wheat is a major cereal crop grown in various parts of the globe, which is affected severely by heat stress. The morphological parameters affected include germination, seedling establishment, source-sink activity, leaf area, shoot and root growth. The physiological parameters such as photosynthesis, respiration, leaf senescence, water and nutrient relation are also affected by heat. At the cellular level, heat stress leads to the generation of reactive oxygen species that disrupt the membrane system of thylakoid, chloroplast and plasma membrane. The deactivation of the photosystem, reduction in photosynthesis and inactivation of rubisco affect the production of photoassimilates and their allocation. This ultimately affects anthesis, grain filling, size, number and maturity of wheat grains, which hamper crop productivity. The interplay of various systems comprising antioxidants and hormones plays a crucial role in imparting heat stress tolerance in wheat. Thus, implementation of various omics technologies could foster in-depth insights on heat stress effects, eventually devising heat stress mitigation strategies by conventional and modern breeding to develop heat-tolerant wheat varieties. This review provides an integrative view of heat stress responses in wheat and also discusses approaches to develop heat-tolerant wheat varieties.

Melatonin Ameliorates Thermotolerance in Soybean Seedling through Balancing Redox Homeostasis and Modulating Antioxidant Defense, Phytohormones and Polyamines Biosynthesis.

Global warming is impacting the growth and development of economically important but sensitive crops, such as soybean (Glycine max L.). Using pleiotropic signaling molecules, melatonin can relieve the negative effects of high temperature by enhancing plant growth and development as well as modulating the defense system against abiotic stresses. However, less is known about how melatonin regulates the phytohormones and polyamines during heat stress. Our results showed that high temperature significantly increased ROS and decreased photosynthesis efficiency in soybean plants. Conversely, pretreatment with melatonin increased plant growth and photosynthetic pigments (chl a and chl b) and reduced oxidative stress via scavenging hydrogen peroxide and superoxide and reducing the MDA and electrolyte leakage contents. The inherent stress defense responses were further strengthened by the enhanced activities of antioxidants and upregulation of the expression of ascorbate–glutathione cycle genes. Melatonin mitigates heat stress by increasing several biochemicals (phenolics, flavonoids, and proline), as well as the endogenous melatonin and polyamines (spermine, spermidine, and putrescine). Furthermore, the positive effects of melatonin treatment also correlated with a reduced abscisic acid content, down-regulation of the gmNCED3, and up-regulation of catabolic genes (CYP707A1 and CYP707A2) during heat stress. Contrarily, an increase in salicylic acid and up-regulated expression of the defense-related gene PAL2 were revealed. In addition, melatonin induced the expression of heat shock protein 90 (gmHsp90) and heat shock transcription factor (gmHsfA2), suggesting promotion of ROS detoxification via the hydrogen peroxide-mediated signaling pathway. In conclusion, exogenous melatonin improves the thermotolerance of soybean plants and enhances plant growth and development by activating antioxidant defense mechanisms, interacting with plant hormones, and reprogramming the biochemical metabolism.

{Protection, Resilience, Efficiency and Prevention} (PREP), preparing workers and employers for a changing climate

BACKGROUND AND AIM: Expensive, often inaccessible, treatment, early death, and economic hardship faces millions of workers in Latin America and Asia due to Chronic Kidney Disease of nontraditional cause (CKDnt). Strenuous work in extreme heat without sufficient rest and hydration is an important driver. We established the Adelante Initiative workplace intervention to prevent CKDnt and kidney injury among workers at a sugarcane mill in Nicaragua. The Initiative focused on heat stress mitigation, hydration and rest systems including electrolyte solutions, mobile tents, rest schedules and education, for workers and management, combined with an organizational assessment to address barriers to implementation. METHODS: PREP builds on Adelante, investigating: 1) impact of the intervention on workforce health and productivity; 2) economic and social impacts of CKDnt 3) economic burden on health systems; 4) public and private-sector policy gaps and solutions. RESULTS:Workers with the heaviest workload had a 12-fold higher risk (95%CI=3.93-35.4) of kidney injury than those with lower workload in the same environment. Despite implementation challenges at the mill including inconsistent provision of shade, hydration and mandated rest, there was a 72% (95%CI=50-90%) reduction of incident kidney injury post intervention. Economic burden on households and health systems is considerable. Public and private sector policies are either nonexistent or inadequate to provide guidance for prevention, or to support detection and treatment of CKDnt. However, the inclusion of initial investments in technical assistance for workplace protections within the development sector and some industries is encouraging. CONCLUSIONS:PREP lays the groundwork to expand to other industries and geographies at-risk for heat stress and CKDnt. Occupational heat stress and resulting CKDnt require increased attention and resources for surveillance, prevention and treatment. Climate change means more extreme temperatures in already impacted regions, and regions further north and south of the equator, putting more workers at risk of CKDnt. KEYWORDS: Temperature extremes and variability, Health co-benefits, Socio-economic factors, Occupational exposures, Exposure assessment-general

Coral microbiome manipulation elicits metabolic and genetic restructuring to mitigate heat stress and evade mortality.

Beneficial microorganisms for corals (BMCs) ameliorate environmental stress, but whether they can prevent mortality and the underlying host response mechanisms remains elusive. Here, we conducted omics analyses on the coral Mussismilia hispida exposed to bleaching conditions in a long-term mesocosm experiment and inoculated with a selected BMC consortium or a saline solution placebo. All corals were affected by heat stress, but the observed "post-heat stress disorder" was mitigated by BMCs, signified by patterns of dimethylsulfoniopropionate degradation, lipid maintenance, and coral host transcriptional reprogramming of cellular restructuration, repair, stress protection, and immune genes, concomitant with a 40% survival rate increase and stable photosynthetic performance by the endosymbiotic algae. This study provides insights into the responses that underlie probiotic host manipulation. We demonstrate that BMCs trigger a dynamic microbiome restructuring process that instigates genetic and metabolic alterations in the coral host that eventually mitigate coral bleaching and mortality.

Heat stress mitigation strategies for beef cattle under intensive finishing in the Mexican dry tropics

Objective: Review the heat stress mitigation strategies in intensive cattle feedlots in the tropical region of México.Approach: Beef cattle production is one of the principal activities of the agricultural sector; therefore, to maintain the inventory in intensive finishing pens, a considerable number of cattle are moved to geographic areas where climatic conditions are not always favorable for most of the year. High environmental temperature combined with relative humidity create heat stress conditions andconsequently affecting the productive indicators by compromising the physiologicalstability of the cattle.Implications: The improvement of housing conditions to mitigate the effects of heat stress in beef cattle in intensive finishing involves considering living space, available shade area, feeding and watering space that assure the cattle welfare during their stay in livestock production units. Conclusions: Heat stress mitigation strategies in beef cattle during intensive finishing in practical conditions should contribute to animal welfare and them improvement of the productive indicators at the Mexican dry tropics.

Biochar Application Mitigates the Effect of Heat Stress on Rice (Oryza sativa L.) by Regulating the Root-Zone Environment.

Coping with global warming by developing effective agricultural strategies is critical to global rice (Oryza sativa L.) production and food security. In 2020, we observed that the effect of heat stress on rice plants was mitigated by biochar application (40 g kg−1 soil) in a pot experiment with six consecutive days (6–11 days after transplanting) of daily mean temperatures beyond the critical high temperature (33°C) for tillering in rice. To further determine the eco-physiological processes underlying the effect of biochar on resistance to heat stress in rice plants, we compared root-zone soil properties as well as some plant growth and physiological traits related to nitrogen (N) utilization between rice plants grown with and without biochar in the pot experiment. The results showed that the application of biochar improved the root-zone environment of rice plants by reducing soil bulk density, increasing soil organic matter content, and altering soil bacterial community structure by increasing the ratio of Proteobacteria to Acidobacteria, for example. As a consequence, root morphology, architecture, and physiological traits, such as N assimilation and transport proteins, as well as shoot N uptake and utilization (e.g., photosystems I and II proteins), were improved or up-modulated, while the heat-shock and related proteins in roots and leaves were down-modulated in rice plants grown with biochar compared to those without biochar. These results not only expand our understanding of the basic eco-physiological mechanisms controlling increased heat-stress tolerance in rice plants by the application of biochar, but also imply that improving the root-zone environment by optimizing management practices is an effective strategy to mitigate heat stress effects on rice production.