Experience Heat Stress Research Articles

Rumen fermentation shifts and microbial dynamics in mid-lactating holstein dairy cows experiencing heat stress and subsequent recovery periods.

In this study, we investigated the effects of heat stress (HS) on rumen fermentation, blood parameters, and ruminal microbial communities in mid-lactating Holstein dairy cows in Korea. Our study involved 12 mid-lactation Holstein dairy cows aged 55.54 months with 2.5 ± 0.65 parities and 100 to 200 days in milking (DIM), fed a total mixed ratio (TMR) diet. Samples were collected during HS (temperature-humidity index (THI) = 81.69) and recovery (RC) period (THI 69.84). The samples were analyzed for rumen fermentation, blood parameters, heat shock proteins, and microbial communities in dairy cows. The milk yield, milk fat, milk protein, and milk urea nitrogen (MUN) levels differed significantly between two -time points (p < 0.05). Rumen pH and volatile fatty acid (VFA) concentrations, the pH was not significantly different (p=0.619) between HS and RC periods; however, the ammonia nitrogen (NH3-N) levels increased during HS period ), however, there was no significant difference (p>0.05). Blood total protein significantly increased during HS period compared with that during RC period (p < 0.05), while no significant differences were observed in other parameters between the two periods. HSP27, HSP70, and HSP90 increased in dairy cows under HS conditions compared with those during the RC period. Taxonomic classification revealed that Firmicutes and Bacteroidetes dominated the bacterial community. PERMANOVA and PERMDISP showed significant differences in rumen bacterial diversity between HS and RC periods, based on Unifrac metrics (p=0.044 and p=0.015, respectively), indicating taxonomic variations. Microbial networks with correlations of > 0.8 (p < 0.05) showed a complex structure with equal positive and negative connections, indicating Anaerohabdus furcosa and Ruminiclostridium cellobioparum as key species during the HS and RC periods respectively. Heat stress significantly impacts Holstein dairy cows' physiological and metabolic processes, altering rumen fermentation, blood biochemistry, and gut microbiota during mid-lactation.

Probiotic strategies for mitigating heat stress effects on broiler chicken performance.

The primary objective of this study was to evaluate the effects of liquid (Fructose-added lactic acid bacteria, F-LAB) and commercial (Commercial LAB, C-LAB) probiotics sourced from Rye-Grass Lactic Acid Bacteria (LAB) on broiler chickens experiencing heat stress (HS). The research involved 240 broiler chicks, divided into six groups: control, F-LAB, C-LAB (raised at 24°C), HS, F-LAB/HS, and C-LAB/HS (exposed to 5-7h of 34-36°C daily). The study followed a randomized complete block design, with each group consisting of 40 chicks. F-LAB and HS/F-LAB groups received a natural probiotic added to their drinking water at a rate of 0.5ml/L, while C-LAB and HS/C-LAB groups were supplemented with a commercial probiotic at the same dosage. Control and HS groups received no probiotic supplementation. The duration of the study was 42days, with data collected on growth performance, feed intake, feed conversion ratio, and health parameters. Statistical analyses were performed using ANOVA, and significant differences between groups were determined using post hoc tests. The results revealed that without probiotic supplementation, heat stress led to a decrease in body weight gain, T3 levels, citrulline, and growth hormone levels, along with an increase in the feed conversion ratio, serum corticosterone, HSP70, ALT, AST, and leptin levels (p < 0.05 for all). Heat stress also adversely affected cecal microbiota, reducing lactic acid bacteria count (LABC) while increasing Escherichia coli and coliform bacteria (CBC) counts. However, in the groups receiving probiotic supplementation under heat stress (F-LAB/HS and C-LAB/HS), these effects were alleviated (p < 0.05 for all). Particularly noteworthy was the observation that broiler chickens supplemented with natural lactic acid bacteria (F-LAB) exhibited greater resilience to heat stress compared to those receiving the commercial probiotic, as evidenced by improvements in growth, liver function, hormonal balance, intestinal health, and cecal microbiome ecology (p < 0.05). These findings suggest that the supplementation of naturally sourced probiotics (F-LAB) may positively impact the intestinal health of broiler chickens exposed to heat stress, potentially supporting growth and health parameters.

A sidewalk-level urban heat risk assessment framework using pedestrian mobility and urban microclimate modeling

Climate change and the associated increase in heat-related hazards pose a pressing threat to urban residents’ health and well-being. People, when walking in particular, are at risk of experiencing heat stress as they navigate urban environments. This study proposes a novel heat risk assessment framework combining pedestrian mobility modeling with urban microclimate modeling. Using this framework, we assessed pedestrian heat-related exposure and risk in urban areas by integrating the Universal Thermal Climate Index (UTCI) as the hazard and pedestrian trips to critical destinations as exposure. We considered temporal variation, in both hazard and exposure, by examining different time periods during the day—morning peak, midday, and evening peak. In addition to hazard and exposure, we also considered vulnerability by focusing on young children and older adults. We contribute to improving the spatial resolution of heat risk assessment by analyzing the hazard for pedestrian trips between home locations and five critical destinations—bus stops, rail stations, parks, schools, and commercial amenities—at the address-point level and using a pedestrian network comprising sidewalks and crosswalks. Our framework helps identify sidewalks with high heat exposure levels as well as home locations with high cumulative heat risk, accounting for walking trips to critical destinations along feasible routes. We demonstrated the effectiveness of this framework by applying it to a 36-square-kilometer area of central Los Angeles, CA. Our findings offer valuable information to urban planners and policy-makers, supporting evidence-based prioritization of intervention sites, climate adaptation strategies, and policy decisions essential for climate-proof planning. By implementing targeted interventions in areas where heat hazard is expected to affect the most vulnerable pedestrians, planners can create heat-resilient, pedestrian-friendly environments while prioritizing the health and well-being of vulnerable groups. This study contributes to the growing knowledge of robust risk assessment methodologies for climate-proof planning, specifically with regard to addressing outdoor heat-related risks during extreme heat events.

Impact of Heat Stress on Oocyte Developmental Competence and Pre-Implantation Embryo Viability in Cattle.

Rectal and vaginal temperatures are utilised in both in vivo and in vitro models to study the effects of heat stress on oocyte competence and embryo viability in cattle. However, uterine temperature increases by only 0.5 °C in heat-stressed cows, significantly lower than simulated increases in in vitro models. Temperature variations within oviducts and ovarian follicles during heat stress are poorly understood or unavailable, and evidence is lacking that oocytes and pre-implantation embryos experience mild (40 °C) or severe (41 °C) heat stress inside the ovarian follicle and the oviduct and uterus, respectively. Gathering detailed temperature data from the reproductive tract and follicles is crucial to accurately assess oocyte competence and embryo viability under realistic heat stress conditions. Potential harm from heat stress on oocytes and embryos may result from reduced nutrient availability (e.g., diminished blood flow to the reproductive tract) or other unidentified mechanisms affecting tissue function rather than direct thermal effects. Refining in vivo stress models in cattle is essential to accurately identify animals truly experiencing heat stress, rather than assuming heat stress exposure as done in most studies. This will improve model reliability and aid in the selection of heat-tolerant animals.

Where is the heat threat in a city? Different perspectives on people-oriented and remote sensing methods: The case of Prague

Extreme heat in urban areas has a severe impact on urban populations worldwide. In light of the threats posed by climate change, it is clear that more holistic and people-oriented approaches to reducing heat stress in urban areas are needed. From this perspective we aim to identify and compare thermal hotspots and places with favourable thermal conditions, based on three different methods – thermal walk, participatory-based cognitive mapping, and remote sensing in a Central European city. Although major hotspots in large low-rise development zones were identified by all three methods, the overall agreement between on-site thermal sensation votes, cognitive maps and surface temperatures is low. In the urban canyon of compact mid-rise and open mid-rise development, the thermal walk method proved to be useful in the identification of the specific (parts of) streets and public spaces where citizens can expect thermal discomfort and experience heat stress, e.g. crossroads, arterial streets with a lack of greenery, north facing unshaded parts of streets, and streets with inappropriate tree spacing. Cognitive maps on an urban neighbourhood scale are not specific enough on a street level; however, as a supplementary method they can help identify discrepancies between on-site sensations and thermal conditions. For further research on effective and cost-efficient urban heat mitigation, we suggest combining thermal walks with numerical model simulations.

Feeling hot is being hot? Comparing the mapping and the surveying paradigm for urban heat vulnerability in Vienna

With rising global temperatures, cities increasingly need to identify populations or areas that are vulnerable to urban heat waves; however, vulnerability assessments may run into ecological fallacy if data from different scales are misconstrued as equivalent. We assess the heat vulnerability of 1983 residents in Vienna by measuring heat impacts, exposure, sensitivity and adaptive capacity with mirrored indicators in the mapping paradigm (i.e. census tract data referring to the geographic regions where these residents live) and the surveying paradigm (i.e. survey data referring to the residents' individual households). Results obtained in both paradigms diverge substantially: meteorological indicators of hot days and tropical nights are virtually unrelated to self-reported heat strain. Meteorological indicators are explained by mapping indicators (R2 of 15–40 %), but mostly not by surveying indicators. Vice versa, experienced heat stress and subjective heat burden are mostly unassociated with mapping indicators but are partially explained by surveying indicators (R2 of 2–4 %). The results suggest that the two paradigms do not capture the same components of vulnerability; this challenges whether studies conducted in the respective paradigms can complement and cross-validate each other. Policy interventions should first define which heat vulnerability outcome they target and then apply the paradigm that best captures the specific drivers of this outcome.

The Effect of Hot Water Scarification Duration on Germination and Growth of Indigofera zollingeriana Seeds

Indigofera zollingeriana is a type of leguminous plant that is excellent for cultivation as forage for ruminant livestock such as cattle, buffalo, goats, and sheep. This study aims to determine the effect of the duration of hot water scarification on the germination of Indigofera zollingeriana seeds. The research was conducted at the Livestock Feed Technology Laboratory of the State Agricultural Polytechnic of Kupang. The study was carried out for 2 weeks using a Completely Randomized Design with 4 treatments and 5 replications, namely P0: without hot water scarification, P1: hot water scarification at 65°C for 30 minutes, P2: hot water scarification at 65°C for 60 minutes, and P3: hot water scarification at 65°C for 90 minutes. The variables measured in this study were germination percentage, mean daily germination, and seedling height. The data obtained were analyzed using analysis of variance (ANOVA), and if there was a significant effect, it was followed by Duncan's test. The results showed that the effect of scarification of Indigofera zollingeriana seeds with hot water at 65°C for different durations significantly affected the parameters of germination percentage and mean daily germination, with the treatment without scarification providing the best results. This could be due to the prolonged duration of soaking, which caused the seeds to experience heat stress. As for the seedling height parameter, the treatment did not have a significant effect. Therefore, hot water scarification with excessively long durations is not recommended as a strategy to promote germination and growth of these seeds.

Feeding Eucommia ulmoides extract enhances protection against high-temperature stress in chicks

Chick's susceptibility to heat stress often leads to growth retardation, immune function impairment, disease, and mortality. This thesis explores the potential ameliorative effect of 0.8% Eucommia ulmoides extract (EUE) into the diet of heat-stressed chicks in a 15-d feeding trial. The investigation reveals that feeding EUE significantly enhances the BW, ADG, AFI, and F/G of chicks experiencing heat stress. Additionally, the EUE groups exhibited higher levels of T-AOC (at 7 and 15d), SOD (at 15 d), GSH-Px (at 15 d), as well as lower MDA concentrations (at 7 and 15d) in chick serum. Pathological changes and H&E staining revealed that EUE effectively improved tissue damage in the duodenum, heart, and stomach induced by heat stress in the chicks. The EUE groups also showed higher levels of IgA (at 7 d), IgG and IgM (at 7 and 15 d). RNA-seq and WGCNA analysis revealed that EUE mitigates cellular damage and losses in heat-stressed chicks primarily through pathways involving signal transduction, protein synthesis and degradation, as well as cell cycle regulation, particularly the latter. This investigation serves as a fundamental and cognitive framework for the development and application of Eucommia ulmoides feed additives aimed at safeguarding the well-being of chicks in adverse environmental conditions.

The Glucose-Succinate Pathway: A Crucial Anaerobic Metabolic Pathway in the Scallop Chlamys farreri Experiencing Heat Stress.

Recently, the increase in marine temperatures has become an important global marine environmental issue. The ability of energy supply in marine animals plays a crucial role in avoiding the stress of elevated temperatures. The investigation into anaerobic metabolism, an essential mechanism for regulating energy provision under heat stress, is limited in mollusks. In this study, key enzymes of four anaerobic metabolic pathways were identified in the genome of scallop Chlamys farreri, respectively including five opine dehydrogenases (CfOpDHs), two aspartate aminotransferases (CfASTs) divided into cytoplasmic (CfAST1) and mitochondrial subtype (CfAST2), and two phosphoenolpyruvate carboxykinases (CfPEPCKs) divided into a primitive type (CfPEPCK2) and a cytoplasmic subtype (CfPEPCK1). It was surprising that lactate dehydrogenase (LDH), a key enzyme in the anaerobic metabolism of the glucose-lactate pathway in vertebrates, was absent in the genome of scallops. Phylogenetic analysis verified that CfOpDHs clustered according to the phylogenetic relationships of the organisms rather than substrate specificity. Furthermore, CfOpDHs, CfASTs, and CfPEPCKs displayed distinct expression patterns throughout the developmental process and showed a prominent expression in muscle, foot, kidney, male gonad, and ganglia tissues. Notably, CfASTs displayed the highest level of expression among these genes during the developmental process and in adult tissues. Under heat stress, the expression of CfASTs exhibited a general downregulation trend in the six tissues examined. The expression of CfOpDHs also displayed a downregulation trend in most tissues, except CfOpDH1/3 in striated muscle showing significant up-regulation at some time points. Remarkably, CfPEPCK1 was significantly upregulated in all six tested tissues at almost all time points. Therefore, we speculated that the glucose-succinate pathway, catalyzed by CfPEPCK1, serves as the primary anaerobic metabolic pathway in mollusks experiencing heat stress, with CfOpDH3 catalyzing the glucose-opine pathway in striated muscle as supplementary. Additionally, the high and stable expression level of CfASTs is crucial for the maintenance of the essential functions of aspartate aminotransferase (AST). This study provides a comprehensive and systematic analysis of the key enzymes involved in anaerobic metabolism pathways, which holds significant importance in understanding the mechanism of energy supply in mollusks.

Effects of Lonicera japonica Extract with Different Contents of Chlorogenic Acid on Lactation Performance, Serum Parameters, and Rumen Fermentation in Heat-Stressed Holstein High-Yielding Dairy Cows.

This examined the effects of Lonicera japonica extract (LJE) with different chlorogenic acid (CGA) contents on lactation performance, antioxidant status and immune function and rumen fermentation in heat-stressed high-yielding dairy cows. In total, 45 healthy Chinese Holstein high-yielding dairy cows, all with similar milk yield, parity, and days in milk were randomly allocated to 3 groups: (1) the control group (CON) without LJE; (2) the LJE-10% CGA group, receiving 35 g/(d·head) of LJE-10% CGA, and (3) the LJE-20% CGA group, receiving 17.5 g/(d·head) of LJE-20% CGA. The results showed that the addition of LJE significantly reduced RT, and enhanced DMI, milk yield, milk composition, and improved rumen fermentation in high-yielding dairy cows experiencing heat stress. Through the analysis of the serum biochemical, antioxidant, and immune indicators, we observed a reduction in CREA levels and increased antioxidant and immune function. In this study, while maintaining consistent CGA content, the effects of addition from both types of LJE are similar. In conclusion, the addition of LJE at a level of 4.1 g CGA/(d·head) effectively relieved heat stress and improved the lactation performance of dairy cows, with CGA serving as the effective ingredient responsible for its anti-heat stress properties.

Reducing consequences of extreme heat: The role of weather information access

This study investigates the impact of weather information sources on consequences associated with extreme heat events, employing a cross-sectional survey conducted on hospitalized individuals who have experienced heat stress in Central Vietnam. Multiple information channels, including official agencies and social media, were found to significantly reduce the Cost of Illness (COI) associated with heat-related ailments. Social media, in particular, emerged as a potent tool for climate adaptation. Improving the clarity and accessibility of weather information through official channels is crucial, especially for households with varying income levels. Demographic factors such as age and gender should be considered when fine-tuning communication strategies, with special attention given to individuals with underlying medical conditions, who are particularly susceptible to extreme heat effects. These findings underscore the need to maximize the reach of weather-related information and reduce economic burdens on affected populations. This provides valuable insights for policymakers aiming to bolster climate resilience in vulnerable regions like Vietnam, emphasizing the significance of diverse information sources and tailored communication in climate change adaptation.

Chitosan oligosaccharides as dietary antioxidants in nutrition of broiler chickens

Chitosan oligosaccharides (COS) have attracted considerable attention in poultry research due to their diverse biological activities and possible effects on the welfare and productivity of broiler chickens. A thorough examination of many studies indicates that the influence of COS on indices such as antioxidative functions, growth performance, immunological responses, and metabolic implications in broilers is significant. For example, specific dosage levels of COS have significantly enhanced antioxidant activity, regulation of cholesterol levels, and improved growth performance. The research findings have provided evidence for COS's antioxidative and anti-inflammatory properties and its capacity to mitigate the effects caused by stress. Nevertheless, the effectiveness of reactions might be influenced by the dosage and may demonstrate variances. Broiler chickens are suggested to consume dietary COS levels between 350 mg/kg and 500 mg/kg feed to obtain antioxidant and immunological advantages. Nevertheless, the most favorable results regarding growth and the ability to absorb nutrients are typically found when the intake ranges from 0.5 g/kg to 1.0 g/kg feed. For yellow-feather broilers experiencing heat stress, it is advisable to administer a dosage of 200 mg/kg feed of COS. However, it is essential to closely observe dosages exceeding 2.5 g/kg since they may significantly impair growth performance. The diverse research on using COS in broiler management has provided valuable insights into its intricate nature. This review has highlighted the potential benefits of COS in enhancing chicken health and nutrition. However, it has also underscored the need for additional research to optimize its effectiveness in broiler production fully. It can be concluded that dietary COS in broiler chickens in doses ranging from 200 mg to 1000 mg/kg feed has a positive effect on growth performance, antioxidative properties, regulation of lipid metabolism, ability to mitigate stress, impact on meat quality, and carcass traits, but exceeding 2.5 g/kg feed may significantly impair in growth performance in the broiler.

The transcription factor MYB1 activates DGAT2 transcription to promote triacylglycerol accumulation in sacha inchi (Plukenetia volubilis L.) leaves under heat stress

Triacylglycerol (TAG) accumulation is frequently triggered in vegetative tissues experiencing heat stress, which may increases plant basal plant thermo-tolerance by sequestering the toxic lipid intermediates that contribute to membrane damage or cell death under stress conditions. However, stress-responsive TAG biosynthesis and the underlying regulatory mechanisms are not fully understood. Here, we investigated the lipidomic and transcriptomic landscape under heat stress in the leaves of sacha inchi (Plukenetia volubilis L.), an important oilseed crop in tropical regions. Under heat stress (45 °C), the content of polyunsaturated TAGs (e.g., TAG18:2 and TAG18:3) and total TAGs were significantly higher, while those of unsaturated sterol esters, including ZyE 28:4, SiE 18:2 and SiE 18:3, were dramatically lower. Transcriptome analysis showed that the expression of PvDGAT2-2, encoding a type II diacylglycerol acyltransferase (DGAT) that is critical for TAG biosynthesis, was substantially induced under heat stress. We confirmed the function of PvDGAT2-2 in TAG production by complementing a yeast mutant defective in TAG biosynthesis. Importantly, we also identified the heat-induced transcription factor PvMYB1 as an upstream activator of PvDGAT2-2 transcription. Our findings on the molecular mechanism leading to TAG biosynthesis in leaves exposed to heat stress have implications for improving the biotechnological production of TAGs in vegetative tissues, offering an alternative to seeds.

Effect of heat stress during the dry period on milk yield and reproductive performance of Holstein cows.

This study aimed to determine the influence of heat stress during the dry period on milk yield and reproductive performance of Holstein cows in a hot environment. Breeding and milk production records of cows, as well as meteorological data between 2017 and 2020 from a commercial dairy herd (n = 12,102 lactations), were used to determine the relationship between climatic conditions during the dry period (average of the temperature-humidity index (THI) at the beginning, middle, and end of the dry period) and reproductive efficiency and milk yield traits. THI was divided into < 70 (no heat stress), 70-80 (moderate heat stress), and > 80 (severe heat stress). First-service pregnancy rate of cows decreased (P < 0.01) with increasing hyperthermia during the dry period (9.5, 7.3, and 3.4% for THI < 70, 70-80, and > 80, respectively). All-service pregnancy rate was highest (P < 0.01) for cows not undergoing heat stress during the dry period (60.2%) and lowest (42.6%) for cows with severe heat stress during the dry period. Cows not experiencing heat stress during the dry period required a mean ± SD of 5.6 ± 3.8 services per pregnancy compared with 6.5 ± 3.6 (P < 0.01) for cows subjected to THI > 80 during the dry period. Cows not suffering heat stress during the dry period produced more (P < 0.01) 305-day milk (10,926 ± 1206kg) than cows subjected to moderate (10,799 ± 1254kg) or severe (10,691 ± 1297kg) heat stress during the dry period. Total milk yield did not differ (P > 0.10) between cows not undergoing heat stress (13,337 ± 3346kg) and cows subjected to severe heat stress during the dry period (13,911 ± 4018kg). It was concluded that environmental management of dry cows during hot months is warranted to maximize reproductive performance and milk yield in the following lactation.

Heat shock proteins, thermotolerance, and insecticide resistance in mosquitoes.

Mosquitoes transmit pathogens that pose a threat to millions of people globally. Unfortunately, widespread insecticide resistance makes it difficult to control these public health pests. General mechanisms of resistance, such as target site mutations or increased metabolic activity, are well established. However, many questions regarding the dynamics of these adaptations in the context of developmental and environmental conditions require additional exploration. One aspect of resistance that deserves further study is the role of heat shock proteins (HSPs) in insecticide tolerance. Studies show that mosquitoes experiencing heat stress before insecticide exposure demonstrate decreased mortality. This is similar to the observed reciprocal reduction in mortality in mosquitoes exposed to insecticide prior to heat stress. The environmental shifts associated with climate change will result in mosquitoes occupying environments with higher ambient temperatures, which could enhance existing insecticide resistance phenotypes. This physiological relationship adds a new dimension to the problem of insecticide resistance and further complicates the challenges that vector control and public health personnel face. This article reviews studies illustrating the relationship between insecticide resistance and HSPs or hsp genes as well as the intersection of thermotolerance and insecticide resistance. Further study of HSPs and insecticide resistance could lead to a deeper understanding of how environmental factors modulate the physiology of these important disease vectors to prepare for changing climatic conditions and the development of novel strategies to prevent vector-borne disease transmission.

Climatic and calf-related risk factors associated with failure of transfer of passive immunity in Holstein calves in a hot environment.

This retrospective observational study aimed to assess the effect of temperature-humidity index (THI) at calving and in the last trimester of pregnancy and calve-related factors affecting passive transfer of maternal immunoglobulin using Brix refractometry in Holstein calves. Blood samples from 4411 Holstein calves from a single large dairy farm in spring 2022 were used. A subset of data containing 6318 calvings was used to determine the effect of climatic conditions on the occurrence of agammaglobulinemia. Risk factors predictive of failure of passive transfer (FPT) were calculated using multiple logistic models. Females were 1.4 times more likely not to have FPT (56%; Brix% > 8 equivalent to ≥ 10g/L IgG) than males (47.2%). Calves born as singles increased the likelihood of not presenting FPT (52.6%) than calves born as twins (42.9%). Calves from cows with no dystocic delivery had a lower risk for FPT (odds ratio = 2.3) than calves from cows with dystocia. Agammaglobulinemia was 1.5 and 1.8 times more likely to occur in calves with THI ≥ 80 and ≥ 82 in the last trimester of gestation and at calving, respectively, than in calves not experiencing heat stress. Agammaglobulinemia was twice as likely to occur in male than in female calves. Calves with birth weight ≥ 37kg and gestation length ≥ 275kg were less likely to present agammaglobulinemia than lighter calves and calves with shorter gestation periods. This study raises questions for management practices in Holstein calves undergoing in utero heat stress and around calving to avoid agammaglobulinemia.

Transcriptomic Response of the Atlantic Surfclam (Spisula solidissima) to Acute Heat Stress

There is clear evidence that the oceans are warming due to anthropogenic climate change, and the northeastern coast of USA contains some of the fastest warming areas. This warming is projected to continue with serious biological and social ramifications for fisheries and aquaculture. One species particularly vulnerable to warming is the Atlantic surfclam (Spisula solidissima). The surfclam is a critically important species, linking marine food webs and supporting a productive, lucrative, and sustainable fishery. The surfclam is also emerging as an attractive candidate for aquaculture diversification, but the warming of shallow coastal farms threatens the expansion of surfclam aquaculture. Little is known about the adaptive potential of surfclams to cope with ocean warming. In this study, the surfclam transcriptome under heat stress was examined. Two groups of surfclams were subjected to heat stress to assess how artificial selection may alter gene expression. One group of clams had been selected for greater heat tolerance (HS) and the other was composed of random control clams (RC). After a 6-h exposure to 16 or 29 °C, gill transcriptome expression profiles of the four temperature/group combinations were determined by RNA sequencing and compared. When surfclams experienced heat stress, they exhibited upregulation of heat shock proteins (HSPs), inhibitors of apoptosis (IAPs), and other stress-response related genes. RC clams differentially expressed 1.7 times more genes than HS clams, yet HS clams had a stronger response of key stress response genes, including HSPs, IAPs, and genes involved with mitigating oxidative stress. The findings imply that the HS clams have a more effective response to heat stress after undergoing the initial selection event due to genetic differences created by the selection, epigenetic memory of the first heat shock, or both. This work provides insights into how surfclams adapt to heat stress and should inform future breeding programs that attempt to breed surfclam for greater heat tolerance, and ultimately bring greater resiliency to shellfish farms.

Use of electrolyte and betaine water supplementation to support improved liveweight gain of commercial Pekin ducks exposed to adverse high temperature in the week prior to processing

Context Commercial Pekin Ducks housed in conventional open-sided sheds often experience heat stress in summer. Electrolyte or osmolyte supplements can help birds cope under heat stress. Aims To assess the effects of water electrolyte/betaine supplementation or betaine in feed on the growth performance of Pekin ducks exposed to high ambient temperature. Methods Commercial Cherry Valley Pekin ducks were fed diets with a dietary electrolyte balance (DEB) of 160 (L-DEB) or 209 (H-DEB) over Days 15–41 (D15–41) of age. Over D36–41, ducks were provided with water alone or supplemented with betaine in the feed (BF), or betaine and an ‘in-house’ electrolyte (E) formulation at 50%, 100% or 150% (D36–41) or at 100% for only 36 h on D40–41. There were 12 treatments with four replicate pens for each treatment. On D36–41 of age, temperature was increased to 28–32°C for 9 h (from 08:30 hours to 17:30 hours) and then returned to 22–24°C for the remainder of the day. Individual liveweights were taken on D28, D35, D41. During these times, feed intake and water consumption were determined. On D41, one male and one female from each pen were weighed, euthanised and breast muscle was removed and weighed. Birds were collected for commercial processing at 04:00 hours on D42. Key results Over D15–35, the DEB had no effect on bird performance. Over D36–41, for liveweight gain (LWG) there were significant interactions between treatment × week (P &lt; 0.001) and treatment × diet (P = 0.017). Supplements E150 and E100 + 36 h supported LWG more than did other treatments, while treatments BF, E50 and E100 supported higher LWG than in controls. On the L-DEB diet, the control birds had a LWG lower than in other treatments (P &lt; 0.05). On the H-DEB diet, the E50 supplement had highest LWG, but comparable to that in E100 + 36 h. The supplements had no effects on breast muscle yield, weight losses during transport and lairage or processed carcass weights. Conclusions The electrolyte supplements supported higher LWG during exposure to moderately adverse high temperature. Supply for 36 h supported LWG equivalent or better than did other treatments given over 6 days. The benefits could be related to increased water intake and not just electrolyte supply. Implications Water electrolyte plus betaine supplementation supports improved Pekin duck performance during a moderately high temperature challenge.

Using a Model to Compare Cooling System Design Factors For Lactating Cows

Highlights Cow mass, milk yield, solar load, air velocity, dry-bulb and dew-point temperature impact lactating cow respiration rates. Modeled respiration rates align with published studies dealing with milk yield, solar load, and evaporative cooling. The model can be used to assess cooling systems for conditions that might be difficult to capture in field measurements. Abstract. The risk of lactating cows experiencing heat stress is increasing because of increased productivity. A steady-state process-based model described by Nelson and Janni (2023) and assessed by Janni et al. (2023) was used to compare additional combinations of environmental conditions (e.g., air dry-bulb and dew-point temperatures, air velocity, solar load) and lactating cow characteristics (e.g., body mass and daily milk yield) on modeled respiration rate. Respiration rate was linked to qualitative heat stress levels, based on work by Renaudeau et al. (2012). The model demonstrates how cows with greater body mass have larger inspired volumes of respired air (i.e., liters per minute) because they have larger tidal volumes (i.e., liters per breath) while they have lower respiration rates (i.e., breaths per minute) compared to cows with smaller body masses. The modeled results support previous studies that demonstrated heat stress increases with greater daily milk yields, solar load, and air dry-bulb and dew-point temperatures. The model finds conditions where increasing air velocity at cow level can help cows reduce heat stress levels due to solar load, and high air dry-bulb and dew-point temperatures. A comparison to a field study demonstrates the need to align field data collection and model input needs to explore the actual or potential impacts of mitigation methods like shade, evaporative cooling, and air velocity (i.e., via fans). This report demonstrates how the model can be used by engineers to investigate the impact of ventilation system designs on respiration rates using current and future technologies. Keywords: Air velocity, Cow mass, Dairy, Dew-point temperature, Dry-bulb temperature, Heat stress, Milk yield, Respiration rate, Solar load.

The Effects of Climate Change on Hawaii’s Coral Reef Ecosystem Over the Past 20 Years

The Hawaiian islands are known for their rich marine biodiversity in coral reef ecosystems. However, in the last 20 years, changes in sea surface temperatures, sea levels, carbon dioxide levels, and ocean pH have severely impacted these reef ecosystems. Hawaiian corals can experience heat stress with temperatures as little as 1-2 °C above the average and thermal stress events were prevalent from 2014-2017, causing bleaching and increasing mortality. The increase in sea level in Hawaiian marine ecosystems has caused reefs to “drown” from the lack of sufficient sunlight and thus suffer from bleaching. Coral disease is linked with high temperatures, seen through the common reef-building coral disease white syndrome. Invasive species outbreaks, with Acanthaster planci as an example, are also correlated with changes in the climate and reef communities. With the loss of coral, there have been consequences on marine biodiversity in Hawaiian reef ecosystems. Specifically, the three most native coral genera, porites, montipora, and pocillopora, which are the most important species to the reefs, have been declining in population. As a result, higher threat statuses have been observed among turtles, reef fish, and marine mammals that are reliant on their coral reef ecosystems for protection and food sources.