Applications of Artificial Intelligence for Heat Stress Management in Ruminant Livestock.

Heat stress impacts ruminant livestock production on varied levels in this alarming climate breakdown scenario. The drastic effects of the global climate change-associated heat stress in ruminant livestock demands constructive evaluation of animal performance bordering on effective monitoring systems. In this climate-smart digital age, adoption of advanced and developing Artificial Intelligence (AI) technologies is gaining traction for efficient heat stress management. AI has widely penetrated the climate sensitive ruminant livestock sector due to its promising and plausible scope in assessing production risks and the climate resilience of ruminant livestock. Significant improvement has been achieved alongside the adoption of novel AI algorithms to evaluate the performance of ruminant livestock. These AI-powered tools have the robustness and competence to expand the evaluation of animal performance and help in minimising the production losses associated with heat stress in ruminant livestock. Advanced heat stress management through automated monitoring of heat stress in ruminant livestock based on behaviour, physiology and animal health responses have been widely accepted due to the evolution of technologies like machine learning (ML), neural networks and deep learning (DL). The AI-enabled tools involving automated data collection, pre-processing, data wrangling, development of appropriate algorithms, and deployment of models assist the livestock producers in decision-making based on real-time monitoring and act as early-stage warning systems to forecast disease dynamics based on prediction models. Due to the convincing performance, precision, and accuracy of AI models, the climate-smart livestock production imbibes AI technologies for scaled use in the successful reducing of heat stress in ruminant livestock, thereby ensuring sustainable livestock production and safeguarding the global economy.

Impact of heat stress during close-up dry period on performance, fertility and immunometabolic blood indices of dairy cows: prospective cohort study.

This study aimed to investigate whether heat stress, as defined by the temperature-humidity index (THI) during the close-up dry period, had any impact on the productive performance, fertility, and immunometabolic blood indices of dairy cows in the subsequent lactation. Lactation performance was associated with increasing THI values on - 21, - 14, and - 7 d before calving resulting in decreased milk yield by about 2.30, 2.60, and 2.90 kg, respectively. The THI on the - 7 d before the calving was negatively associated with fertility parameters such as delayed first estrus postpartum, an elongated calving interval by approximately 32 d, a higher number of services per conception by 1.00, and an elongated artificial insemination service period, days open, and inter-calving period by about 20, 52, and 52 d, respectively. The study found that the immunometabolic blood indices were associated with increasing THI values during the close-up dry period. The study showed that exposing dairy cows to close-up dry period heat stress had negative consequences on performance, fertility, and immunometabolic blood indices in the subsequent lactation. Therefore, it is recommended that herd management and barn microclimate changes be implemented earlier, starting from the late dry period, to mitigate the negative impact of heat stress.

Terminalia bellirica and Andrographis paniculata dietary supplementation in mitigating heat stress-induced behavioral, metabolic and genetic alterations in broiler chickens.

BACKGROUND: Heat stress (HS) is one of the most significant environmental stressors on poultry production and welfare worldwide. Identification of innovative and effective solutions is necessary. This study evaluated the effects of phytogenic feed additives (PHY) containing Terminalia bellirica and Andrographis paniculata on behavioral patterns, hematological and biochemical parameters, Oxidative stress biomarkers, and HSP70, I-FABP2, IL10, TLR4, and mTOR genes expression in different organs of broiler chickens under chronic HS conditions. A total of 208 one-day-old Avian-480 broiler chicks were randomly allocated into four treatments (4 replicate/treatment, 52 birds/treatment): Thermoneutral control treatment (TN, fed basal diet); Thermoneutral treatment (TN, fed basal diet + 1 kg/ton feed PHY); Heat stress treatment (HS, fed basal diet); Heat stress treatment (HS, fed basal diet + 1 kg/ton feed PHY). RESULTS: The findings of the study indicate that HS led to a decrease in feeding, foraging, walking, and comfort behavior while increasing drinking and resting behavior, also HS increased red, and white blood cells (RBCs and WBCs) counts, and the heterophile/ lymphocyte (H/L) ratio (P < 0.05); while both mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were decreased (P < 0.05). In addition, HS negatively impacted lipid, protein, and glucose levels, liver and kidney function tests, and oxidative biomarkers by increasing malondialdehyde (MDA) levels and decreasing reduced glutathion (GSH) activity (P < 0.05). Heat stress (HS) caused the upregulation in HSP70, duodenal TLR4 gene expression, and the downregulation of I-FABP2, IL10, mTOR in all investigated tissues, and hepatic TLR4 (P < 0.05) compared with the TN treatment. Phytogenic feed additives (PHY) effectively mitigated heat stress's negative impacts on broilers via an improvement of broilers' behavior, hematological, biochemical, and oxidative stress biomarkers with a marked decrease in HSP70 expression levels while all tissues showed increased I-FABP2, IL10, TLR4, and mTOR (except liver) levels (P < 0.05). CONCLUSION: Phytogenic feed additives (PHY) containing Terminalia bellirica and Andrographis paniculata have ameliorated the HS-induced oxidative stress and improved the immunity as well as the gut health and welfare of broiler chickens.

Strategies to combat heat stress in Isa Brown layer hens: Unveiling the roles of vitamin A, vitamin E, vitamin K, vitamin C, selenium, folic acid, and in combination.

Background: Due to their efficient insulation, lack of sweat glands, relatively quick metabolic rate, and heightened sensitivity to heat, the poultry industry faces a serious problem with heat stress. Combining vitamins has been demonstrated to be more effective than implementing a single vitamin in reducing the effects of heat stress. Aim: This study aimed to investigate the efficacy of the multivitamin combination in feed on the growth performance, egg quality, and antioxidant enzymes in laying hens exposed to heat stress. Methods: A total of 28 Isa Brown strains aged 18 weeks were randomly designated into seven groups with four replications, i.e., (C-) normal temperature group, (C+) heat stress group, and the others with the administration of vitamin A and E (AE), vitamin K and C (KC), vitamin C and E (CE), vitamin E and selenium (ESE), and vitamin C and folic acid (CAF). Feed intake, feed efficiency, eggshell thickness, shape index, haugh unit (HU), yolk, and albumen index were evaluated at 22, 23, 24, and 25 weeks. Meanwhile, antioxidant enzymes were quantified at 22 and 25 weeks. Results: As a result, feed intake was reported a significant improvement in the AE and CE groups compared to the C+ group. Meanwhile, the feed efficiency was reported to be efficient in the CE and ESE groups. Based on egg quality evaluation, we reported significant shell thickness in the CE, ESE, and CAF groups compared to the C+; yolk index was reported slightly significant results in the AE and CAF groups; albumen index and HU were reported to increase significantly in the CAF group. Meanwhile, superoxide dismutase (SOD), malondialdehyde (MDA), and GPx activity were ameliorated significantly in the ESE and CAF groups. Conclusion: Combinations of multivitamins can thereby enhance feed intake, feed efficiency, egg quality, and antioxidant activity. The CE, ESE, and CAF groups were found to have made equivalent improvements in the eggshell thickness, shape index, HU, yolk, and albumen index.

Predictive models for heat stress assessment in Holstein dairy heifers using infrared thermography and machine learning.

Heat stress is a condition that impairs the animal's productive and reproductive performance, and can be monitored by physiological and environmental variables, including body surface temperature, through infrared thermography. The objective of this work is to develop computational models for classification of heat stress from respiratory rate variable in dairy cattle using infrared thermography. The database used for the construction of the models was obtained from 10 weaned heifers, housed in a climate chamber with temperature control, and submitted to thermal comfort and heat wave treatments. Physiological and environmental data were collected, as well as thermographic images. The machine learning modeling environment used was IBM Watson, IBM's cognitive computing services platform, which has several data processing and mining tools. Classifier models for heat stress were evaluated using the confusion matrix metrics and compared to the traditional method based on Temperature and Humidity Index. The best accuracy obtained for classification of the heat stress level was 86.8%, which is comparable to previous works. The authors conclude that it was possible to develop accurate and practical models for real-time monitoring of dairy cattle heat stress.

Turmeric essential oil improves intestinal integrity, immunological parameters, and performance of broiler chickens under cyclic heat stress.

This study aimed to examine whether dietary supplementation of broiler chickens with turmeric essential could mitigate the effects of cyclic heat stress conditions. Intestinal and immunological parameters and gene expression were evaluated during the grower phase. A total of 320 21-day-old male Cobb 500 broilers were distributed according to a completely randomized design with a 4 (diet) × 2 (environment) factorial arrangement and eight replications of five birds each. Dietary treatments consisted of a basal diet without essential oil (EO, negative control) and three diets containing low (100 mg kg-1), intermediate (200 mg kg-1), or high (300 mg kg-1) levels of turmeric EO. In the heat stress group, dietary supplementation with turmeric EO at 100 and 200 mg kg-1 improved body weight, feed conversion, breast yield, and relative liver weight. These supplementation levels reduced villus width, increased villus/crypt ratio, reduced the H/L ratio, and improved hepatic (HSP70 and SREBP1) and intestinal (OCLN) gene expression in birds under heat stress. These findings support the hypothesis that turmeric EO can be used to improve or restore intestinal integrity, modulate inflammation parameters, and, consequently, enhance the performance of broilers challenged by cyclic heat stress.

Betaine and feed restriction as potential mitigation strategies against heat stress in two strains of laying hens.

Climate change is increasingly manifesting in temperate regions. Laying hens are highly sensitive to heat stress and mitigation strategies should be implemented to reduce the negative effects. The goal of this experiment was to evaluate the effects of betaine in drinking water (0.55 g/L) and 4 h feed restriction during peak heat stress on laying performance, egg quality, blood gas parameters, body temperature (Tb), and oxidative stress in 2 different breeds of laying hens. Therefore, 448 ISA Brown hens (25 wk) and 448 Lohmann LSL classic laying hens (26 wk) were housed in 128 cages (7 hens/cage). Thermoneutral (TN) data was collected for 21 d before cyclic heat stress (HS) (21d; 32 ± 2°C; 6 h daily). During HS, hens were divided into 4 treatments: 1) feed restriction (FR), 2) betaine supplementation in drinking water (BET), 3) feed restriction and betaine supplementation in drinking water (FR-BET), or 4) control (CON). The effects were evaluated after 1 wk of HS (acute heat stress; AHS) and 3 wk of HS (chronic heat stress; CHS). Laying rate and egg mass (EM) diminished during CHS but decreased more in white than brown hens (2.78% and 1.94%; -1.57% and -0.81%, respectively; P = 0.004) and remained unaltered by BET or FR. During AHS, average daily feed intake (ADFI) increased compared to TN, but the increase was higher in white than brown hens (6.36% and 2.62%, respectively; P = 0.001). Egg shell quality deteriorated during AHS and CHS, but was most affected in white hens, FR or BET did not impact this. Blood pCO2, HCO3- and base excess significantly decreased during AHS and CHS, but pH and iCa were unaltered. Blood glucose increased in white hens during AHS compared to TN (P < 0.001), while plasma malondialdehyde increased in brown hens (P < 0.001). Results indicated that laying hens experienced HS, but breed differences were observed and white hens were generally most affected. FR affected feed conversion ratio negatively during CHS. However, FR and BET could not improve laying performance, egg quality, Tb, or blood parameters during HS.

Assessment of the effects of heat stress on the production of dairy cows by using two comfort thermal indices in Southern Chile.

Heat stress has been recognized as a serious problem in dairy farms around the world due to the increasing heat waves and higher genetic potential of dairy cows. In Chile, milk production is concentrated in the southern regions of the country, where animals graze all year around, consequently being exposed directly to environmental conditions. Nevertheless, there are few studies conducted in Chile that have evaluated at the commercial level the impact of heat stress on milk production. The aim of this study was to assess the effects of summer conditions, across periods, on the milk production of cows at different stages of lactation in a dairy farm located in Southern Chile. Daily meteorological and milk yield records of three summers from a dairy farm were collected to characterize the relationship between two thermal stress indices and milk yield. The thermal comfort indices used were the comprehensive climate index (CCI), and the adjusted temperature humidity index (THIadj). The average values of CCI and THIadj were dependent on the period (P < 0.0001) with maximum CCI of 40.2 °C, 31.7 °C, and 27.5 °C for the 2012-2013, 2015-2016, and 2016-2017 periods, respectively. A similar response was recorded when THIadj was used (85.5, 78.0, and 73.9, respectively). In the 2012-2013 summer, 44.4% of the days presented conditions of heat stress (CCI ≥23), a value that fell to 26.7% in the summer of 2015-2016 and only 5.6% in the 2016-2017. On the opposite, when the THIadj was used, these values were 50%, 48.9%, and 5.6%, respectively. In conclusion, both comfort thermal indices are good tools to determine the risk of thermal stress in dairy cows, with a large variation between the three summer periods but also between indices. Likewise, cows in the early and mid-lactation periods are more affected in terms of milk yield.

Review: Ruminant heat-stress terminology.

With increasing climate variability, there is a rise in the exposure to, and incidence of, ruminant heat stress (HS), increasing the requirement for focused research. As such, precise terminology is crucial to maintain effective communication and knowledge advancement. Despite this, several key terms are currently defined inconsistently, leading to confusion and misinterpretation. This paper examines the historical and contemporary use of the terms 'resistance', 'tolerance', 'resilience', and 'susceptibility' across various disciplines, revealing significant ambiguities that hinder both research and practice. Through this comprehensive review, we propose new definitions for each term as they are used relating to HS, with a focus on ruminant production. Proposed definitions align with current scientific understanding, providing a robust framework for future research and application. As further research is conducted, we hope these definitions can be improved through the inclusion of quantitative measures which align with these classifications. This present review provides definition clarity for common heat abatement terminology, enabling consistency and from this, progress in the field to ameliorate HS for ruminants.

Relationship between metabolic indices and milk yield in Saanen goats exposed to heat stress in semi-tropical climates.

This study aimed to determine the effects of heat stress on 30 Saanen goats of different ages (young, middle-aged, and old). The average temperature and humidity values during the trial were 27.82 °C and 40.65%, respectively. Statistically significant differences in pulse rate (PR), respiratory rate (SS), and temperature humidity index (THI) were found between months (P < 0.05). Beta-hydroxybutyric acid (BHBA) values were found to be statistically significant in the young and middle-aged group (P < 0.05), with the highest in the middle-aged group obtained in June (0.65 mmol/L). Non-esterified fatty acids (NEFA) and urea (BUN) were significantly different (P < 0.05) in all age groups, whereas creatinine values showed no significant differences between groups. Significant positive relationships were found between body weight (BW) and body condition score (BCS), as well as pulse rate (PR) and daily average daily milk yield (DAMY) (P < 0.01). A positive correlation was also found between the respiratory rate (SS) and pulse rate (P < 0.01). As a result, although attempts have been made to prevent the decrease in productivity with applications for animals under heat stress, the optimal strategy may be to address the source of the problem. Issues that cause heat accumulation in the body should be identified and necessary arrangements should be made in the shelter to distribute heat to ensure that animals are less affected. Shaded areas should be provided in cases of stress caused by heat. An appropriate structural arrangement for temperature, humidification, and ventilation systems, as well as the provision of abundant fresh drinking water, would also be beneficial.

Effect of seven days heat stress on feed and water intake, milk characteristics, blood parameters, physiological indicators, and gene expression in Holstein dairy cows.

This study examined the effects of 7 days of heat stress on eight early lactating Holstein cows in climate-controlled chambers. The early lactating Holstein cows (42 ± 2 days in milk, 29.27 ± 0.38 kg/day milk yield, 1.21 ± 0.05 parity) were subjected to two 14-day periods, each consisting of 7 days of adaptation and 7 days of heat stress. Conditions were set to 22 °C and 50% humidity during adaptation, followed by heat stress periods with low-temperature, low-humidity (LTLH, 71 THI) and high-temperature, high-humidity (HTHH, 86 THI) treatments. Data from the last 7 days were analyzed using a mixed procedure in SAS. In the study, the HTHH group displayed marked physiological and biochemical changes on 14 days of heat stress exposure compared to the LTLH group. Firstly, the HTHH group's dry matter intake decreased by approximately 12% while their water intake increased by about 23%. Secondly, both milk yield and milk protein production in the HTHH group decreased by 10% and 20%, respectively. Thirdly, there was a reduction in white blood cells, hemoglobin, mean corpuscular hemoglobin, and platelets in the HTHH group, with concurrent increases in glucose, non-esterified fatty acids, and albumin concentrations. Additionally, the HTHH group exhibited elevated plasma concentrations of cortisol and haptoglobin. Moreover, the gene expression of heat shock protein 70 and heat shock protein 90 was significantly upregulated in the HTHH group's peripheral blood mononuclear cells. Lastly, key physiological indicators such as rectal temperature, heart rate, and skin temperature showed substantial elevations in the HTHH group. Considering the enormous negative effects observed in the analyzed blood metabolites, milk yield and compositions, and heat shock protein gene expression, early lactating Holstein cows were found to be more vulnerable to HTHH than LTLH over a 7 days exposure to heat stress.

Livestock-Forest integrated system attenuates deleterious heat stress effects in bovine oocytes.

Global warming poses significant challenges to the fertility of tropical dairy cattle. One promising approach to mitigate heat stress effects on reproductive function and reduce the carbon footprint is the use of integrated livestock-forest (ILF) systems. The aim of this study was to investigate the effects of two different systems, namely Full Sun (FS) and ILF, on maternal hyperthermia and oocyte quality of Holstein and Girolando heifers during the tropical summer season. The temperature-humidity index (THI) data revealed intense heat stress during the experiment. Both the system (P<0.01) and the breed (P<0.01) factors had a significant impact on vaginal temperature, being hyperthermia more pronounced in the FS system and in the Holstein breed. Over the five time points collected at a 33-day interval, we observed distinct patterns for ILF (P=0.65) and FS (P<0.001) systems, suggesting an adaptive response in animals kept in FS systems. Furthermore, oocyte quality assessment revealed an effect of the system for oocyte diameter (P<0.001) and levels of IGFBP2 (P<0.001), and caspase 3 levels showed a decrease in ILF compared to FS for both Holstein (P<0.001) and Girolando (P<0.001) breeds. Collectively, these parameters indicate that oocyte quality during the summer months was superior in animals maintained in the ILF system. In conclusion, the ILF system demonstrated promising results in attenuating maternal hyperthermia and mitigating its effects on oocyte quality. Additionally, our observations suggest that animals in the FS system may exhibit an adaptive response to heat stress.

Functional oil in the feeding of heat-stressed Japanese quail.

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

Rumen-protected methionine modulates body temperature and reduces the incidence of heat stress temperatures during the hottest hours of the day of grazing heat-stressed Bos indicus beef cows.

This study evaluated the effects of supplementation of rumen-protected methionine (RPM) on body thermoregulation and conception rate of Nelore cows exposed to high temperature-humidity index (THI). On -31 days before the artificial insemination protocol, 562 lactating, multiparous cows were assigned to receive (MG) or not (CG) RPM supplementation (3 g/cow mixed into 100 g of mineral supplement). Both groups remained in tropical pastures and received supplementation for 77 days. A subset of cows (n = 142) remained with an intravaginal thermometer collecting intravaginal temperature (IT). The respective minimum, average, and maximum environmental THI were 72.8, 78.0, and 83.3. Effects of treatment × hour of the day were detected (P < 0.0001) for IT. From 1330 to 1730 h and 1830 to 1900 h, IT was higher (P < 0.05) for CG versus MG cows when exposed to moderate and high THI. The supplementation with RPM did not affect conception rate (CG = 64.4% vs. MG = 58.2%; P > 0.05). In conclusion, 3 g of RPM supplementation lowered internal body temperature and possibly altered critical THI threshold in Nelore cows with no impact on reproduction.

Unravelling the impact of heat stress on daughter pregnancy rate in Mehsana buffalo through innovative breeding interventions.

Heat stress profoundly affects the reproductive success of buffaloes, which are vital for the dairy industry due to their unique anatomical and physiological characteristics, necessitating careful evaluation under such conditions. Hence, this guided our search for quantifying heat stress' impact on Mehsana buffaloes using the best THI model and evaluating sires' performance. Fertility records (days open converted to daughter pregnancy rate) were collected in the span of over 24 years, w.e.f. 1989 to 2012. Finally, 3070 records of first lactation cows, daughters of 117 sires from DURDA, Gujarat, India, were used in the analysis. Meteorological data were retrieved from IMD, Pune, to understand the relationship between daughter pregnancy rate (DPR) and heat stress indicators. Several heat stress models were compared based on R2, adjusted R2, AIC, and BIC values, and the impact of heat stress was quantified. The year was classified into different heat stress zones, viz., Non heat stress zone (NHSZ), Heat stress zone (HSZ), and critical heat stress zone (CHSZ), drawing from the findings of DPR and THI. The THI 4th model based on dry and wet bulb temperature was identified as the best-fit model, and DPR significantly changed (P < 0.01) by 1.14% per unit change in THI value based on the month of calving. The average EBVs of the sires for DPR were found to be 20.78% (NHSZ), 38.09% (HSZ), and 39.08% (CHSZ) using BLUP-SM and 20.78% (NHSZ), 37.30% (HSZ), and 38.87% (HSZ) using BLUP-AM. Subsequently, the optimum sire for each of the zones was prioritized. It is noteworthy that bulls that performed better in NHSZ did not perform as well in HSZ and CHSZ, and vice versa. This supports the possibility of evaluating bulls independently in each heat stress zone.

Influence of thermal heat load accumulation on daily rumination time of lactating Holstein cows in a zone with temperate climate.

In the future, conflicts between animal welfare and climate change will gradually intensify. In the present study, we investigated the daily rumination time (RT) of lactating Holstein-Friesian cows in a zone with temperate climate and the effects of heat load duration and heat load intensity. Responses of individual cows to heat load were assessed, adjusting for milk yield, lactation number, days in milk as well as reproductive status and season. A total of 27,149 data points from 183 cows in a naturally ventilated barn in Brandenburg, Germany, were collected from June 2015 to May 2017. Ambient temperature and relative humidity were recorded at eight positions inside the barn every 5 min, and the temperature-humidity index (THI) was calculated. Based on THI, the degree of heat load was determined, using critical thresholds of THI = 68, 72, and 80. Daily RT was measured with a microphone-based sensor system (collar) on the cow's neck. The analysis models included autocorrelations in time series as well as individual cow-related effects. With each 5 min exposure to contemporaneous heat load, a decrease of approximately 1.17 min d-1 in RT per cow from non-heat stress to heat stress conditions by exceeding THI ≥68 (p < 0.01). This effect was intensified by exceeding the critical THI thresholds of 68 and 72. As heat load duration and intensity increased, daily RT decreased in comparison to daily RT under non-stress conditions. High-yielding (>38.4 kg milk/day) cows were more influenced in rumination time than low-yielding (≤28.8 kg milk/day) cows. With moderate contemporaneous heat load, RT decreased by 0.14 min d-1 per 5 min in high-yielding cows compared to low-yielding cows under moderate heat load. A decrease of 0.1 min d-1 was found in daily RT of mid-yielding cows. However, the delayed effects of heat load (one to three days after the heat stress event) were associated with days in milk and reproduction status. When the heat load duration lasted for several days, the responses were less pronounced than the impacts of contemporaneous heat load (when the heat stress event lasted for one day). Delayed mild heat load resulted in an increase in RT by 0.13 min d-1 in lactating cows ≤60 DIM. This was also found with delayed moderate heat load. Lactating cows ≤60 DIM showed a rise of 0.09 min d-1 in RT. RT also showed interactions with reproduction status of cows under delayed moderate heat stress. Lactating cows with ≤180 days of pregnancy showed an increase of 0.61 min d-1 in RT. Similarly, cows with >180 days of pregnancy had 0.64 min d-1 more RT compared to non-pregnant cows. Further analysis with higher temporal resolution of RT than data accumulation in 24-h blocks as well as the assessment of the correlation between feed composition, intake and rumination will elucidate the influence of heat load on daily RT.

Potential of exogenous melatonin administration to mitigate heat stress induce pathophysiology of chicken.

Melatonin (MT) is an amine hormone secreted by the body that has antioxidant and anti-inflammatory properties. The aim of this study was to investigate pathophysiological protection of MT in heat-stressed chickens. By modelling heat-stressed chickens and treating them with MT. After 21 days of administration, serum antioxidant enzymes, biochemical indices, inflammatory cytokine and heat-stress indices were detected, along with cardiopulmonary function indices and histological observations in chickens. The results show heat-stress induced a decrease (P < 0.05) in body weight and an increase in body temperature, which was reversed after MT intervention. Treatment with MT inhibited (P < 0.05) the secretion of pro-inflammatory factors interleukin-1ß, interleukin-6, tumor necrosis factor α, serum heat shock protein 70, corticosterone, and elevated (P < 0.05) the levels of biochemical factors total protein, albumin, globulin, and increased (P < 0.05) the activities of antioxidant enzymes superoxide dismutase, glutathione peroxidase and catalase in chicken serum caused by heat stress, and the best effect was observed with the medium dose of MT. The heat-stress caused cardiac atrophy and pulmonary congestion, decreased (P < 0.05) the cardiac function indices creatine kinase isoenzyme, cardiac troponin I, angiotensin receptor I, creatine kinase and lung function indices myeloperoxidase, angiotensin-II, heat shock factor I, and increased (P < 0.05) the lung vascular endothelial growth factor II. Sections of the heart and lungs after administration of MT were observed to be more complete with more normal tissue indices. At the same time, compared with heat stress, heart and lung function indices of grade chickens after MT administration were significantly (P < 0.05)reduced and tended to normal levels, and the best effect was observed in the medium-dose MT. In conclusion, heat stress can cause pathophysiological damage in chickens, and 1 mg/kg/d of exogenous melatonin can attenuate this adverse effect.

Establishment and risk factor assessment of the abnormal body temperature probability prediction model (ABTP) for dairy cattle.

The study aims to develop an abnormal body temperature probability (ABTP) model for dairy cattle, utilizing environmental and physiological data. This model is designed to enhance the management of heat stress impacts, providing an early warning system for farm managers to improve dairy cattle welfare and farm productivity in response to climate change. The study employs the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm to analyze environmental and physiological data from 320 dairy cattle, identifying key factors influencing body temperature anomalies. This method supports the development of various models, including the Lyman Kutcher-Burman (LKB), Logistic, Schultheiss, and Poisson models, which are evaluated for their ability to predict abnormal body temperatures in dairy cattle effectively. The study successfully validated multiple models to predict abnormal body temperatures in dairy cattle, with a focus on the temperature-humidity index (THI) as a critical determinant. These models, including LKB, Logistic, Schultheiss, and Poisson, demonstrated high accuracy, as measured by the AUC and other performance metrics such as the Brier score and Hosmer-Lemeshow (HL) test. The results highlight the robustness of the models in capturing the nuances of heat stress impacts on dairy cattle. The research develops innovative models for managing heat stress in dairy cattle, effectively enhancing detection and intervention strategies. By integrating advanced technologies and novel predictive models, the study offers effective measures for early detection and management of abnormal body temperatures, improving cattle welfare and farm productivity in changing climatic conditions. This approach highlights the importance of using multiple models to accurately predict and address heat stress in livestock, making significant contributions to enhancing farm management practices.

Effects of dietary curcumin nano-micelles on performance, biological responses, and thermal stress resilience in heat-stressed fattening lambs across varying temperature-humidity index conditions: Implications for climate change.

Heat stress poses a significant challenge to sheep farming in arid and semi-arid regions, impacting growth performance, health, and physiological responses. While sheep have innate mechanisms to manage heat stress, prolonged exposure impairs their performance and health. This study evaluated the influence of varying doses of Curcumin Nano-Micelle (CNM) on heat-stressed fattening lambs in northeastern Iran over three months, examining the relationship between CNM doses and growth performance, feeding behavior, physiological responses, immune function, and antioxidant status. Thirty-two crossbred male lambs were included in a completely randomized design with four treatments and eight replications. The experimental treatments were as follows: 1) CTRL: No dietary inclusion of CNM, (control group); 2) T20: Dietary inclusion of 20 mg of CNM per head per day; 3) T40: Dietary inclusion of 40 mg of CNM per head per day; and 4) T80: Dietary inclusion of 80 mg of CNM per head per day. The results revealed that dietary supplementation with 20 and 40 mg of CNM significantly improved live body weight, weight gain, average daily gain (ADG), and feed conversion ratio (FCR) compared to the control treatment. Regression analysis demonstrated quadratic models between growth performance parameters and the Temperature-Humidity Index (THI), indicating a correlation between CNM doses and the animals' responses to heat stress. Regarding eating behavior, CNM doses of 40 and 80 mg/day significantly reduced eating time while increasing ruminating time. Blood analysis indicated significant reductions in glucose levels across all treatments, with T40 significantly reducing both cholesterol and triglyceride (TG) levels. Additionally, CNM supplementation decreased serum malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, indicating enhanced antioxidant status. Physiological responses were influenced by CNM, notably reducing rectal temperature (RT), skin temperature (ST), respiration rate (RR), while pulse rate (PR) increased across various time intervals, particularly in the T80 group. This study demonstrates that CNM supplementation can enhance performance, physiological responses, and antioxidant status in heat-stressed fattening lambs, highlighting its potential to mitigate heat stress effects in sheep farming.

Therapeutic effects of mitoquinol during an acute heat stress challenge in growing barrows.

Study objectives were to determine the effects of mitoquinol (MitoQ, a mitochondrial-targeted antioxidant) on biomarkers of metabolism and inflammation during acute heat stress (HS). Crossbred barrows [n = 32; 59.0 ±â€…5.6 kg body weight (BW)] were blocked by BW and randomly assigned to 1 of 4 environmental-therapeutic treatments: 1) thermoneutral (TN) control (n = 8; TNCon), 2) TN and MitoQ (n = 8; TNMitoQ), 3) HS control (n = 8; HSCon), or 4) HS and MitoQ (n = 8; HSMitoQ). Pigs were acclimated for 6 d to individual pens before study initiation. The trial consisted of two experimental periods (P). During P1 (2 d), pigs were fed ad libitum and housed in TN conditions (20.6 ±â€…0.8 °C). During P2 (24 h), HSCon and HSMitoQ pigs were exposed to continuous HS (35.2 ±â€…0.2 °C), while TNCon and TNMitoQ remained in TN conditions. MitoQ (40 mg/d) was orally administered twice daily (0700 and 1800 hours) during P1 and P2. Pigs exposed to HS had increased rectal temperature, skin temperature, and respiration rate (+1.5 °C, +6.8 °C, and +101 breaths per minute, respectively; P < 0.01) compared to their TN counterparts. Acute HS markedly decreased feed intake (FI; 67%; P < 0.01); however, FI tended to be increased in HSMitoQ relative to HSCon pigs (1.5 kg vs. 0.9 kg, respectively; P = 0.08). Heat-stressed pigs lost BW compared to their TN counterparts (-4.7 kg vs. +1.6 kg, respectively; P < 0.01); however, the reduction in BW was attenuated in HSMitoQ compared to HSCon pigs (-3.9 kg vs. -5.5 kg, respectively; P < 0.01). Total gastrointestinal tract weight (empty tissue and luminal contents) was decreased in HS pigs relative to their TN counterparts (6.2 kg vs. 8.6 kg, respectively; P < 0.01). Blood glucose increased in HSMitoQ relative to HSCon pigs (15%; P = 0.04). Circulating non-esterified fatty acids (NEFA) increased in HS compared to TN pigs (P < 0.01), although this difference was disproportionately influenced by elevated NEFA in HSCon relative to HSMitoQ pigs (251 µEq/L vs. 142 µEq/L; P < 0.01). Heat-stressed pigs had decreased circulating insulin relative to their TN counterparts (47%; P = 0.04); however, the insulin:FI ratio tended to increase in HS relative to TN pigs (P = 0.09). Overall, circulating leukocytes were similar across treatments (P > 0.10). Plasma C-reactive protein remained similar among treatments; however, haptoglobin increased in HS relative to TN pigs (48%; P = 0.03). In conclusion, acute HS exposure negatively altered animal performance, inflammation, and metabolism, which were partially ameliorated by MitoQ.

Heat stress (HS) compromises animal health and productivity, and this causes major economic losses in almost every livestock sector. The negative consequences of HS are thought to originate from intestinal barrier dysfunction and subsequent immune activation. The underlying causes of lost intestinal integrity during HS are likely multifactorial; however, intestinal ischemia, increased accumulation of reactive oxygen species, and the ensuing epithelial oxidative damage might be potential causes. Mitochondria-targeted antioxidants, such as mitoquinol (MitoQ), are probably more effective than traditional dietary antioxidants (i.e., selenium, vitamin E) at alleviating oxidative stress, as they localize and accumulate within the mitochondria, potentiating their antioxidant activity. Thus, the present study aimed to investigate MitoQ's role during a thermal event in growing pigs. Herein, HS increased all body temperature indices, decreased feed intake (FI), and induced substantial body weight (BW) loss. Interestingly, the reduction in FI and BW was less dramatic in pigs receiving MitoQ. Changes in circulating metabolism and the acute phase response were observed due to the HS challenge; however, contrary to our expectations, these changes were not offset by MitoQ administration. Although our results suggest a positive MitoQ effect on growth performance, future studies are needed to corroborate the replicability of this response during HS.