Temperature-humidity Index Research Articles

Effect of different air speeds at cow resting height in freestalls on heat stress responses and resting behavior in lactating cows in Wisconsin

Heat abatement (e.g., soakers, fans) effectively reduces the negative physiological and production effects of heat stress, but no previous studies have documented effective interventions for the reduced lying times observed in response to hot weather. Although likely adaptive for heat dissipation, the reduction in motivated lying behavior may be an animal welfare concern. We evaluated the effect of air speed from fans with variable frequency drives on the heat stress responses of cows in a naturally ventilated freestall barn. Eight groups of lactating Holsteins (16 cows/group) were exposed to 3 treatments in a replicated crossover design: control (fans off, 0.4 ± 0.2 m/s, measured 0.5 m above the stall surface to represent cow resting height) vs. 60% (1.7 ± 0.5 m/s; ≥ 1 m/s in all stalls) and 100% (2.4 ± 0.8 m/s) fan power. Each treatment was applied for 3 d of acclimation and 4 d of data collection. The effects of treatment on daily maximum vaginal temperature (VT) and lying time (LT; both measured with data loggers), respiration rate (RR; recorded from video), unshaved scapular skin temperature (ST), milk yield (MY), and dry matter intake (DMI) were analyzed using linear mixed models. All models included the fixed effect of treatment and a repeated term for treatment day within group of cows, with group as the subject. The models for LT, VT, and RR also included a fixed effect for same-day Temperature Humidity Index (THI; recorded in the pens with data loggers) and the THI × treatment interaction. The models for DMI and MY, using data from the latter 3 d of each treatment period, also included a fixed effect for the previous day's THI and the -1 d THI × treatment interaction. Lying time differed among treatments (100% vs. 60% fan power vs. control: 14.2 vs. 13.9 vs. 13.2 h/d, respectively, SEM = 0.15 h/d), but both fan treatments prevented the reduction in LT observed in the control treatment as THI increased. Relative to the control, both fan treatments effectively reduced ST, RR, and VT and increasing DMI and MY. In the control, average values were elevated for both RR (68.7 ± 1.5 breaths/min, mean ± SEM, greater than a common benchmark of 60 breaths/min) and VT (39.3 ± 0.05°C) but remained in the normal range in both fan treatments (54.2 vs. 50.7 breaths/min in the 60% vs. 100% fan power treatments; 39.0°C in both fan treatments). Both fan treatments resulted in greater overall MY (42.6 vs. 43.0 ± 0.4 kg/d in the 60% vs. 100% fan power treatments) relative to the control (41.0 kg/d) and similarly avoided the reduction in MY when -1 d THI increased. Compared with natural ventilation alone, fans delivering air speeds of at least 1 m/s at cow resting height were effective not only for reducing thermoregulatory responses, but also for maintaining lying time, DMI, and milk yield in heat stress conditions. This is the first study to demonstrate an intervention to improve animal welfare by maintaining lying times during periods of heat stress.

Effects of different energy levels and two levels of temperature–humidity indices on growth, blood metabolites, and stress biomarkers in Korean native calves

This study investigated the effects of dietary energy levels on growth, blood metabolites, and stress biomarkers in Korean native calves subjected to heat stress (HS). Twenty-four calves (BW: 221.5 ± 24.9 kg; age: 162 ± 4.8 d) were randomly housed in climate-controlled chambers using 3 × 2 factorial design. There were three treatment groups including low energy (LE = 2.53), medium energy (ME = 2.63), and high energy levels (HE = 2.72 Mcal/kg of DM) and two stress levels (threshold: THI = 70–73; severe: THI = 89–91). The calves were adapted to 22 °C for 7 days, then to the target THI level for 14 days. Energy intake, average daily gain, and gain to feed ratio were determined to decline (p < 0.05) under severe HS compared with threshold. Under severe HS, rectal temperature was increased 0.67 °C compared with threshold. Severe HS increased glycine, ammonia, and 3-methylhistidine concentrations compared with threshold (p < 0.05). Gluconeogenic AAs in the blood were increased among the various energy levels regardless of HS. In PBMCs the expression of HSP70 gene was increased in the LE group (p < 0.05), and the HSP90 gene expression was increased in LE and ME groups (p < 0.05) under severe HS. However, the expression of genes HSP70 and HSP90 in HE group did not differ under severe HS (p > 0.05). It has been suggested that HE intake may have a beneficial effect on PBMCs by mitigating ATP depletion. No differences in growth performance were found when increasing energy intake with high protein (CP 17.5%) under HS. However, the increase in energy levels resulted in increased gluconeogenic AAs but decreased urea and 3-methylhistidine in blood. In conclusion, increased energy levels are thought to improve HS adaptability by inhibiting muscle degradation and glucose production using gluconeogenic AAs in Korea native calves under HS condition.

Assessment of Ruminating, Eating, and Locomotion Behavior during Heat Stress in Dairy Cattle by Using Advanced Technological Monitoring.

Heat stress (HS) significantly impacts dairy farming, prompting interest in precision dairy farming (PDF) for gauging its effects on cow health. This study assessed the influence of the Temperature-Humidity Index (THI) on rumination, eating, and locomotor activity. Various parameters, like rumination time, drinking gulps, chews per minute, and others were analyzed. The hypothesis was that precision dairy farming technology could help detect HS. Nine healthy Lithuanian Black-and-White cows were randomly selected for the trial. RumiWatch noseband sensors recorded behaviors, while SmaXtec climate sensors monitored THI. The data collection spanned from 14 June to 30 June. Cows in the THI class ≥ 72 exhibited reduced drinking time (51.16% decrease, p < 0.01), fewer chews per minute (12.9% decrease, p < 0.01), and higher activity levels (16.99% increase, p < 0.01). THI showed an inverse correlation with drinking time (r = -0.191, p < 0.05) and chews per bolus (r = -0.172, p < 0.01). Innovative technologies like RumiWatch are effective in detecting HS effects on behaviors. Future studies should explore the impact of HS on RWS biomarkers, considering factors such as lactation stage, number, yield, and pregnancy.

Multi-objective optimization of supply air jet enhancing airflow uniformity in data center using Taguchi/CRITIC/TOPSIS triple method

Jet fans have been introduced into under-floor air distribution systems as an active local measure to reduce hot spot temperatures and improve airflow distribution uniformity in data centers. However, as the rack load increases, the two jet fans are insufficient to balance the airflow distribution in the hotspot area, more jet fans and the corresponding parameters need setting and optimizing. A couple of methods of criteria importance through intercriteria correlation/technique for order preference by similarity to ideal solution were introduced as a multi-criteria decision making method to solve this problem. The optimal design parameters of multiple jet fans were determined by combining the Taguchi method with Computational Fluid Dynamics. The contribution of each parameter to the evaluation index was calculated by signal-to-noise ratio analysis and analysis of variance using Taguchi method, and the nozzle angle was determined to be the most important parameter. Then, Taguchi method was combined with criteria importance through intercriteria correlation/technique for order preference by similarity to ideal solution to transform the multi-objective into a single-objective to determine the optimal combination of design parameters for multiple jet fans. Finally, the best combination case was verified by evaluation indexes including supply heat index, return temperature index, ratio of temperature differentials and index of mixing. In the optimal combination, the highest server temperature was reduced by 5.3 °C compared with two jet fans. The multi-criteria decision making method is suitable for choosing the optimal parameter combination of airflow organization when faced with complex decisions involving several dimensions.

Eco-Environmental Quality Assessment Using the Remote Sensing Ecological Index in Suzhou City, China

This study utilizes four environmental indicators derived from six-phase Landsat images (TM, OLI, and TIRS) to construct a remote sensing ecological index (RSEI) and to quantitatively and comprehensively assess the spatiotemporal changes in the eco-environmental quality (EEQ) of Suzhou City, China. The environmental indicators consist of the wetness index (WI), greenness index (GI), dryness index (DI), and heat index (HI). The obtained results showed: (1) positive effects of the WI and GI, as well as negative effects of the DI and HI, on the EEQ of Suzhou City in the 2002–2022 period. The GI was observed to have the greatest impact on the RSEI of Suzhou City. (2) The average RSEI values of Suzhou City exhibit a “W” shape pattern in the 2002–2022 period. The lowest and highest average RSEI values were 0.632 and 0.746, respectively, while the average annual RSEI value was 0.702. The EEQ of Suzhou City was observed to be at a relatively good level. (3) The EEQ of Suzhou City exhibits sharp declines in the periods of 2006–2010 and 2014–2018, for which the degraded RSEI area covers 440.60 and 404.16 km2, while the area ratios are 56.13% and 51.48%, respectively. The EEQ of Suzhou City has substantially increased during the periods of 2010–2014, 2018–2022, and 2002–2022, showing improved RSEI areas of 583.7, 390.13, and 347.02 km2 and area ratios of 74.36%, 49.70%, and 44.21%, respectively. The results of this study provide a scientific basis for the protection, utilization, and development of the ecological environment (EE) of Suzhou City. They also provide valuable references and data support for the sustainable development, the high-quality development of the EE, and the construction of the ecological civilization of Suzhou City. The policymakers of environmental protection departments in Suzhou City can use this study’s inferences to devise local environmental protection policies.

Development of a hot weather warning tool for heat index monitoring in Thailand

This study aims to develop and test an extremely hot weather warning tool. The tool consists of a Node MCU ESP8266 microcontroller, air temperature and relative humidity sensor (DHT22), real time clock module (DS3231), micro-SD-card adapter (HW-125), display screen (2004A), and breadboard-shield. It is connected and controlled by Arduino IDE program. Its measurement ranges for temperature, humidity, and heat index are &lt;10 to &gt;50°C, 0 to 100%, and &lt;27 to &gt;50°C, respectively. This device also presents real-time health impacts by displaying one of five warning levels, namely 1) normal level (HI &lt; 27°C), 2) caution level (HI 27°C to &lt;32°C), 3) extreme caution level (HI 32°C to &lt;41°C), 4) danger level (HI 41°C to &lt;54°C), and 5) extreme danger level (HI ≥ 54°C). The data can be directly transferred to a computer by a card adapter. Based on validation with the occupational health and safety standards instrument, no outliers or missing data were found. HIEHT had a highly positive correlation with HIQT36 (r=0.99; p&lt;0.01; n=4,182). Heat Index data measured by this tool was found to have acceptable values with a bias of 0.54 and RMSE of 0.99. For the pilot areas tested, it was found that the extremely hot weather warning tool can fully measure and record, as well as continuously display the results according to the tested date and time. These results show that the developed tool is a simple, easy-to-use, inexpensive, tiny, and portable instrument that can be used to monitor and measure heat to widely communicate extremely hot weather warning information to vulnerable groups and the general public in the community.

Effect of Slow-Release Urea Partial Replacement of Soybean Meal on Lactation Performance, Heat Shock Signal Molecules, and Rumen Fermentation in Heat-Stressed Mid-Lactation Dairy Cows.

This study aimed to assess the effects of partially substituting soybean meal in the diet with slow-release urea (SRU) on the lactation performance, heat shock signal molecules, and environmental sustainability of heat-stressed lactating cows in the middle stage of lactation. In this study, 30 healthy Holstein lactating dairy cattle with a similar milk yield of 22.8 ± 3.3 kg, days in milk of 191.14 ± 27.24 days, and 2.2 ± 1.5 parity were selected and randomly allocated into two groups. The constituents of the two treatments were (1) basic diet plus 500 g soybean meal (SM) for the SM group and (2) basic diet plus 100 g slow-release urea and 400 g corn silage for the SRU group. The average temperature humidity index (THI) during the experiment was 84.47, with an average THI of >78 from day 1 to day 28, indicating the cow experienced moderate heat stress conditions. Compared with the SM group, the SRU group showed decreasing body temperature and respiratory rate trends at 20:00 (p < 0.1). The substitution of SM with SRU resulted in an increasing trend in milk yield, with a significant increase of 7.36% compared to the SM group (p < 0.1). Compared to the SM group, AST, ALT, and γ-GT content levels were significantly increased (p < 0.05). Notably, the levels of HSP-70 and HSP-90α were significantly reduced (p < 0.05). The SRU group showed significantly increased acetate and isovalerate concentrations compared with the SM group (p < 0.05). The prediction results indicate that the SRU group exhibits a significant decrease in methane (CH4) emissions when producing 1 L of milk compared to the SM group (p < 0.05). In summary, dietary supplementation with SRU tended to increase the milk yield and rumen fermentation and reduce plasma heat shock molecules in mid-lactation, heat-stressed dairy cows. In the hot summer, using SRU instead of some soybean meal in the diet alleviates the heat stress of dairy cows and reduces the production of CH4.

Sensitivity Analysis of Heat Stress Indices

More than 40 heat indices are being used across the world to quantify outdoor thermal comfort. The selection of an Outdoor Heat Stress Index (OHSI) depends on several parameters, including clothing, age, awareness, local environment, food consumption, human activities, and resources. This study investigates various indicators of heat stress, including (i) OHSIs officially used to quantify heat stress worldwide, (ii) the estimation methods of these indices, and (iii) the sensitivity analysis of indices, namely, Corrected Effective Temperature (CET), Heat Index (HI), Wet Bulb Globe Temperature (WBGT), Universal Thermal Climate Index (UTCI), Discomfort Index (DI), Summer Simmer Index (SSI), and Predicted Mean Vote (PMV). The results indicate the degree of sensitivity of indices, with the HI being the most sensitive for estimating heat stress. Additionally, the WBGT, HI, and CET are recommended indices that can be directly measured using sensors instead of relying on calculated indices that are based on estimation techniques and some ideal physical assumptions.

THERMAL STRESS PROJECTION BASED ON TEMPERATURE-HUMIDITY INDEX (THI) UNDER CLIMATE CHANGE SCENARIO

The degradation of green open spaces and the phenomenon of deforestation in Indonesia has increased discomfort in the region. Furthermore, if allowed to continue, the increase in temperature caused by greenhouse gases worsens the situation. Increased temperature and reduced air humidity are related to thermal stress, affecting human comfort and health. Thermal stress is measured based on the Temperature Humidity Index (THI), which calculates temperature and relative humidity variables. This study analyses THI projections under climate change scenarios RCP4.5 and RCP8.5. This study uses statistical downscaling and bias correction of Quantile Delta Mapping (QDM) to equalize the local climate. This study is divided into four 20-year periods from 2021 to 2100 to evaluate THI changes in future projections. Based on the study results, it is known that from 2041-2060, several big cities in Indonesia experienced an increase in THI and were included in the category of 50% of the population feeling uncomfortable. THI increased in the third and fourth periods. Areas that experienced a significant increase in THI were urban areas that lacked green open land and were densely populated. Surabaya City and Madura Island are the areas with the highest THI index.

Interactions of particulate matter with temperature, heat index and relative humidity on pediatric hand, foot, and mouth disease in a subtropical city

The associations of hand, foot, and mouth disease (HFMD) with meteorological variables and particulate matter (PM) remain controversial, and limited evidence is available on heat index (HI) and coarse particulate (PM10-2.5). Moreover, temperature and humidity are considered major risk factors but their interaction with PM remains unclear. We combined the distributed lag non-linear and quasi-Poisson models to estimate the non-linear and lagged associations of meteorological variables and PM with HFMD based on reported HFMD during 2015–2019 in Fuzhou, China. The multiplicative term of interaction was used to explore the relationship between HFMD and meteorological variables or PM at different levels of another variable. Stratified analyses were used to identify vulnerable subpopulations. We observed inverted-V-shaped relationships between HFMD and temperature and HI, and the W- and N-shaped for relative humidity (RH) and PM, respectively. Extreme high (i.e., the 95th percentile) temperature, HI and RH increased the HFMD with relative risks (RR) of 4.00 (95% confidence interval, 2.79–5.75), 2.20 (1.71–2.83) and 1.54 (1.35–1.75) referent to the minimum effect value of 10.3 °C, 69.4 and 54.8%, respectively. Higher concentrations of PM rapidly increased the HFMD. Infants under 2 years suffered more from temperature, HI and PM. There were synergistic effects between meteorological variables and PM on HFMD. For instance, the RRs of temperature (30 °C) and RH (40%) on HFMD increased from 3.68 (2.24–6.06) to 6.44 (4.29–9.66) and from 0.45 (0.14–1.47) to 2.15 (0.90–5.12) at low (<25%) and high (>75%) categories of PM2.5, respectively. While the RRs of 70 μg/m3 of PM10 and PM10-2.5 increased from 0.65 (0.32–1.31) to 2.93 (1.63–5.26) and from 0.86 (0.23–3.21) to 3.26 (1.23–8.62) at low and high categories of HI. These findings are essential for the development a prediction and warning systems and prevention and control strategies for HFMD.

Vulnerability assessment of urban agglomerations to the risk of heat waves in China since the 21st century

In the context of global warming, frequent heat wave disasters have seriously threatened the safety of human life and property. The urban agglomeration, as the main region with a high concentration of population and economy, is susceptible to heat weaves due to the existing urban heat island effect. In this study, we investigated the temporal and spatial characteristics of heat waves (heat index, HI) in China from 2000 to 2020 and assess the vulnerability of 19 urban agglomerations to heat waves from the perspective of exposure, sensitivity and adaptability. The results show that: (1) In the past 20 years, the frequency and intensity of HI (greater than 26.67 °C) both showed an upward trend. (2) Shandong Peninsula, Central Henan, Yangtze River Delta, Middle Reaches of Yangtze River, and Mid-southern Liaoning urban agglomerations always maintain a high vulnerability. (3) From 2000 to 2020, the vulnerability of Beijing-Tianjin-Hebei, Yangtze River Delta, Chengdu-Chongqing, Middle reaches of Yangtze River, Guangdong-Fujian-Zhejiang, Harbin-Changchun and Mid-southern Liaoning urban agglomerations were always dominated by exposure. The vulnerability of Shandong Peninsula, Beibu Gulf and Central Henan urban agglomeration has always been dominated by sensitivity. The vulnerability of North Tianshan Mountain, Lanzhou-Xining, Guanzhong and Hu-Bao-E-Yu urban agglomeration has always been dominated by inadequate adaptability. (4) Recently, the factors that contributed most to exposure, sensitivity and adaptability were population density, the proportion of outdoor workers and water supply, with contribution rates of 38%, 55% and 26%, respectively. This study can provide a scientific basis for the rational allocation of resources among urban agglomerations, effectively formulating policies and guiding population migration from high temperature disasters.

The Effect of Month of Harvesting and Temperature-Humidity Index on the Number and Quality of Oocytes and In Vitro Embryo Production in Holstein Cows and Heifers.

The aim of this study was to evaluate the effect of the month of oocyte harvesting and the temperature-humidity index on oocyte number and quality harvested from Holstein cows and heifers, oocyte developmental competence, and total embryos produced in an area of intense ambient temperature for most of the year. A total of 5064 multiparous lactating cows and 2988 nulliparous heifers were used as oocyte donors and distributed across the months of the year. Overall, total oocytes per collection did not differ (p > 0.05) between cows (16.6 ± 2.7) and heifers (15.1 ± 1.8), but oocyte developmental competence was lower (p < 0.05) in cows (21.3 ± 5.4) than heifers (25.5 ± 4.0). For cows, the total number of oocytes harvested was two-fold higher (p < 0.05) in November than in May. For heifers, the total number of oocytes harvested was highest in April (17.19 ± 0.53) and lowest in May (10.94 ± 0.32; p < 0.05). For cows, total embryos were highest in November (2.58 ± 0.42) and lowest in August (1.28 ± 0.10; p < 0.05). Thus, taken together, these results indicate that severe heat stress impaired the number and quality of oocytes harvested from donor Holstein multiparous cows and heifers, oocyte developmental competence, and total embryos produced in this area of intense ambient temperature for most of the year.

The autumn low milk yield syndrome in Brown Swiss cows in continental climates: hypotheses and facts.

Extensive research has been conducted globally on the impact of heat stress (HS) on animal health and milk production in dairy cows. In this article, we examine the possible reasons for the decrease in milk production in Brown Swiss (BS) cows during the autumn season, known as the autumn low milk yield syndrome (ALMYS). This condition has been extensively studied in high-yielding Holstein Friesian (HF) cattle and has also been observed in BS cows with a daily milk yield of around 30kg. Our hypothesis is that the drop in milk yield and the increased prevalence of mastitis in autumn, as found in our recent studies, may be a long-term consequence of summer HS. We re-evaluate our previous findings in light of the possible manifestation of an HS-related form of ALMYS in BS cows. As milk yield, mastitis spread, and reproductive function of cows are interrelated and have seasonal dependence, we examine the consistency of our hypothesis with existing data. The significant drop in milk yield in BS cows in autumn (by 2.0-3.2kg), as well as the threshold of milk yield decrease (temperature-humidity index of 70.7), may point in favour of the manifestation of ALMYS in BS cows, similar to HF cows. Only the percentage effect of seasonal factor (59.4%; p < 0.05) on milk yield of BS cows was significant. HS-related ALMYS provides a robust conceptual framework for diverse sets of productive and animal health data in BS cows, similar to observations in high-yielding HF cattle. However, the limitations associated with the lack of additional data (e.g. immunological indicators) suggest the need for further research to confirm ALMYS in BS breed.

Global risk of heat stress to cattle from climate change

Cattle farming is a major source of global food production and livelihoods that is being impacted by climate change. However, despite numerous studies reporting local-scale heat impacts, quantifying the global risk of heat stress to cattle from climate change remains challenging. We conducted a global synthesis of documented heat stress for cattle using 164 records to identify temperature-humidity conditions associated with decreased production and increased mortality, then projected how future greenhouse gas emissions and land-use decisions will limit or exacerbate heat stress, and mapped this globally. The median threshold for the onset of negative impacts on cattle was a temperature-humidity index of 68.8 (95% C.I.: 67.3–70.7). Currently, almost 80% of cattle globally are exposed to conditions exceeding this threshold for at least 30 days a year. For global warming above 4°C, heat stress of over 180 days per year emerges in temperate regions, and year-round heat stress expands across all tropical regions by 2100. Limiting global warming to 2°C, limits expansion of 180 days of heat stress to sub-tropical regions. In all scenarios, severity of heat stress increases most in tropical regions, reducing global milk yields. Future land-use decisions are an important driver of risk. Under a low environmental protection scenario (SSP3-RCP7.0), the greatest expansion of cattle farming is projected for tropical regions (especially Amazon, Congo Basin, and India), where heat stress is projected to increase the most. This would expose over 500 million more cattle in these regions to severe heat risk by 2090 compared to 2010. A less resource-intensive and higher environmental protection scenario (SSP1-RCP2.6) reduces heat risk for cattle by at least 50% in Asia, 63% in South America, and 84% in Africa. These results highlight how societal choices that expand cattle production in tropical forest regions are unsustainable, both worsening climate change and exposing hundreds of millions more cattle to large increases in severe, year-round heat stress.

Influence of dietary fiber content and horn status on thermoregulatory responses of Brown Swiss dairy cows under thermoneutral and short-term heat stress conditions

In the present experiment, 10 horned and 10 disbudded mid-lactating Brown Swiss cows were included in a crossover feeding trial with a hay or hay and concentrate diet. The effects of dietary neutral detergent fiber (NDF) content and horn status on thermoregulatory responses under thermoneutral and short-term heat stress conditions were studied, as both are considered to ease the cow's thermoregulation under an environmental heat load. Cows received either ad libitum hay and alfalfa pellets (85:15, C-, NDF content: 41.0%) or restricted amounts of hay and concentrate (70:30, C+, NDF content: 34.5%). The level of restriction applied with the C+ diet was determined from pre-experimental ad libitum intakes, ensuring that both diets provided the same intake of net energy for lactation (NEL). For data collection, cows were housed in respiration chambers for 5 d. The climatic conditions were 10°C and 60% relative humidity (RH), considered thermoneutral (TN) conditions (temperature-humidity index (THI): 52) for d 1 and 2, and 25°C and 70% RH, considered heat stress (HS) conditions (THI: 74), for d 4 and 5. On d 3, the temperature and RH were increased gradually. Compared with TN, HS conditions increased the water intake, skin temperature, respiration and heart rates, and endogenous heat production. They did not affect body temperature, feed intake, or milk production. Lowering dietary fiber content via concentrate supplementation lowered methane and increased carbon dioxide production. It did not mitigate physiological responses to HS. Although the responses of horned and disbudded cows were generally similar, the slower respiration rates of horned cows under HS conditions indicate a possible, albeit minor, role of the horn in thermoregulation. In conclusion, future investigations on nutritional strategies must be conducted to mitigate mild heat stress.

Effect of Solar Powered Cooling System to Counteract Heat Stress in Stall Fed HF Deoni Crossbred Cows

Background: During summer the environmental conditions exceeds beyond threshold limit, that enhances heat gain beyond that lost from the body and induces heat stress in cows. The higher temperature and heat stress increases respiration rate, rectal temperature and temperature humidity index, which affects health of the cows. The objective of the study was to create favourable environmental conditions to reduce heat stress and to improve the performance of the cows. Methods: The solar powered cooling system was developed and installed at Main Agriculture Research Station, University of Agricultural Sciences, Raichur District of Karnataka. The functional components of the developed cooling system are foggers, timer-switch, solar panels, battery, water tank, charge controller and hosepipe. The solar panels act as an energy source for the operation pump and the 4-way fogger assembly provides the fogging of water and creates a healthy environment by reducing the air temperature. The system assessment was carried out with 3 levels of variables of foggers (6, 12 and 18 foggers), height of fogger (2.25, 2.50 and 2.75 m) and operational time interval (2, 4 and 6 min). These were statistically analysed along with air temperature (AT), relative humidity (RH), and respiration rate (RR) were also measured. Result: The AT, RH and RR was significantly influenced by the treatment combinations of selected variables and it was found that reduction of 9.2 oC in AT and 49 % (29 breaths min-1) in RR and 47 % increase in RH (66 %) were recorded at 18 foggers at 2.75 m height with 4 min operational time interval. Thus, the developed cooling system was significant (P less than 0.001) in creating optimum environmental conditions for the wellbeing of milch animals.

Single-step genomic predictions for heat tolerance of production yields in US Holsteins and Jerseys

The physiological stress caused by excessive heat affects dairy cattle health and production. This study sought to investigate the impact of heat stress on test-day yields in United States (US) Holstein and Jersey cows and develop single-step genomic predictions to identify heat tolerant animals. Data included 12.8 and 2.1 million test-day records for 923,026 Holstein and 153,710 Jersey cows in 27 US states. From 2015 through 2021, test-day records from the first 5 lactations included milk, fat, and protein yields (kg). Cows' records were included if they had at least 5 test-day records per lactation. Heat stress was quantified by analyzing the impact of a 5-d hourly average temperature-humidity index (THI5d¯) on observed test-day yields. Using a multiple trait repeatability model, a heat threshold (THI threshold) was determined for each breed based on the point that the average adjusted yields started to decrease, which was 69 for Holsteins and 72 for Jerseys. An additive genetic component of general production and heat tolerance production were estimated using a multiple trait reaction norm model and single-step genomic BLUP methodology. Random effects were regressed on a function of THI5d¯ and THI threshold. The proportion of test-day records that occurred on or above the respective heat thresholds was 15% for Holstein and 10% for Jersey. Heritability of milk, fat, and protein yields under heat stress for Holsteins increased, with a small standard error, indicating that the additive genetic component for heat tolerance of these traits was observed. This was not as evident in Jersey traits. For Jersey, the permanent environment explained the same or more of the variation in fat and protein yield under heat stress indicating that non-genetic factors may determine heat tolerance for these Jersey traits. Correlations between the general genetic merit of production (in the absence of heat stress) and heat tolerance genetic merit of production traits were moderate in strength and negative. This indicated that selecting for general genetic merit without consideration of heat tolerance genetic merit of production may result in less favorable performance in hot and humid climates. A general GEBV for genetic merit and a heat tolerance GEBV were calculated for each animal. This study contributes to the investigation of the impact of heat stress on US dairy cattle production yields and offers a basis for the implementation of genomic selection. The results indicate that genomic selection for heat tolerance of production yields is possible for US Holsteins and Jerseys, but a study to validate the genomic predictions should be explored.

Effects of heat stress abatement on systemic and mammary inflammation in lactating dairy cows

To examine the effects of evaporative cooling on systemic and mammary inflammation of lactating dairy cows, 30 multiparous Holstein cows (parity = 2.4, 156 d in milk) were randomly assigned to 1 of 2 treatments: cooling (CL) with fans and misters or not (NC). The experiment was divided into a 10-d baseline when all cows were cooled, followed by a 36-d environmental challenge when cooling was terminated for NC cows. The onset of environmental challenge was considered as d 1. Temperature-humidity index averaged 78.4 during the environmental challenge. Milk yield and dry matter intake (DMI) were recorded daily. Blood and milk samples were collected from a subset of cows (n = 9/treatment) on d -3, 1, 3, 7, 14, and 28 of the experiment to measure cortisol, interleukin 10 (IL10), tumor necrosis factor-α (TNF-α), haptoglobin, and lipopolysaccharide binding protein (LBP). Mammary biopsies were collected from a second subset of cows (n = 6/treatment) on d -9, 2, 10, and 36 to analyze gene expression of cytokines and haptoglobin. A subset of cows (n = 7/treatment) who were not subjected to mammary biopsy collection received a bolus of lipopolysaccharides (LPS) in the left rear quarter on d 30 of the experiment. Blood was sampled from cows and milk samples from the LPS-infused quarter were collected at -4, 0, 3, 6, 12, 24, 48, and 96 h relative to infusion, for analyses of inflammatory products. Deprivation of cooling decreased milk yield and DMI. Compared with CL cows, plasma cortisol concentration of NC cows was higher on d 1 but lower on d 28 of the experiment (cooling × time). Deprivation of cooling did not affect circulating TNF-α, IL10, haptoglobin, or LBP. Compared with CL cows, NC cows tended to have higher milk IL10 concentrations but did not show effects in TNF-α, haptoglobin, or LBP. No differences were observed in mammary tissue gene expression of TNF-α, IL10, and haptoglobin. Milk yield declined after LPS infusion but was not affected by treatment. Compared with CL cows, NC cows had greater milk somatic cell count following intramammary LPS infusion. Non-cooled cows had lower circulating TNF-α and IL10 concentrations and tended to have lower circulating haptoglobin concentrations than CL cows. Milk IL10 and TNF-⍺ concentrations were higher 3 h after LPS infusion for NC cows compared with CL cows. Additionally, NC cows tended to have higher milk haptoglobin concentration after LPS infusion than CL cows. In conclusion, deprivation of evaporative cooling had minimal effects on lactating cows' basal inflammatory status, but upregulated mammary inflammatory responses after intramammary LPS infusion.

Trends in the risk of heat stress to Canadian dairy cattle in a changing climate

Canada's climate is warming faster than the global average, but the warming is unevenly distributed. This study analyzes historical and future climate change in dairy-producing regions across Canada to better understand how Canada's dairy cows are affected. Historical changes (i.e., 1960–2019) were assessed using temperature and humidity data from 29 weather stations across the country. The temperature–humidity index (THI) was used as an indicator of dairy cattle at risk of heat stress, and three THI metrics evaluated the frequency, severity, and duration of potential heat stress. Future scenarios were investigated using five global climate models to project daily THI under three Shared Socioeconomic Pathways (SSPs). Projections were grouped into three time periods (2020–2049, 2040–2069, and 2060–2089). Historical climate trends show an increase in temperature, humidity, and THI exceedance in most west coast and eastern Canada locations, affecting 84% of the national dairy herd. Future scenarios project that 90% of the national herd will experience a large increase in the frequency, severity, and duration of THI exceedance under all but the most optimistic SSP. These findings highlight the need for Canadian dairy farmers to consider heat-stress adaptation strategies.

Impact of Climate Change on the Major Eco-Hydrological Parameters in the Dongting Lake Basin

Quantifying the impacts of climate change on evapotranspiration (ET) and gross primary production (GPP) in the Dongting Lake Basin is essential for assessing water scarcity and implementing sustainable development strategies. Premised on actual measurements and remote sensing data from 47 stations, the impact of climate change on eco-hydrological parameters in the Dongting Lake Basin was analyzed in the present study using the BESS model (The Breathing Earth System Simulator), ridge regression analysis, stepwise regression model and time-lag analysis. The results reveal that: (1) the Dongting Lake Basin has been warm and arid over the last four decades, with the frequent occurrence of extreme climate events. Vegetation carbon sequestration capacity exhibited a slightly upward trend with 0.0081 g C m−2 d−1/year from 2000–2017. ET changed with rates of −3.309 mm/year, with possible risk conflicts between water demand and supply in the future. (2) The increasing temperature was the main driver of ET enhancement in the Dongting Lake Basin. Meanwhile, both temperature and precipitation were found to be the dominant drivers of GPP enhancement. The effect of temperature on GPP was found to be greater in the areas covered by crops and tree vegetation, and natural vegetation was more strongly influenced by precipitation than radiation. (3) Extreme temperature events have had a significant impact on evapotranspiration (ET) and gross primary production (GPP) in the Dongting Lake Basin. Specifically, the cold index in extreme temperature events was found to significantly affect ET, while the heat index in extreme temperature events significantly affected GPP. Additionally, both ET and GPP were found to respond to extreme precipitation events in the region. The results of the study established that vegetation is highly sensitive to temperature, especially temperature extremes, and that precipitation also has a stressful effect. Increasing temperatures and precipitation within a range benefit vegetation productivity. (4) In the Dongting Lake Basin, we found that different climatic factors produced different time lag effects on GPP and ET by time lag analysis. This study highlights the lag effects of climate factors and extreme climate events on eco-hydrological parameters. We suggest incorporating the effects into simulation models of eco-hydrological parameters. This will lead to a better understanding of the variation of eco-hydrological parameters under climate change.