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.

The serum irisin response to prolonged physical activity in temperate and hot environments in older men with hypertension or type 2 diabetes.

Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m2) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (Tco) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite Tco not being different between groups, Tco was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury.

The influence of acclimatization on stress hormone concentration in serum during heat stress.

This study was aimed to examine the influence of acclimatization on the change of concentration of stress hormones in men's serum exposed to heat stress during physical training. The study included a total of 40 men, aged 19-21 years, divided randomly into four groups: CTRL group: control, exposed to the Exercise Tolerance Testing in comfortable conditions; O group: exposed to Exercise Tolerance Testing in a warm environment; P group: exposed to passive acclimation to heat for 10 days, followed by Exercise Tolerance Testing in a warm environment; A group: exposed to active acclimation to heat for 10 days, followed by Exercise Tolerance Testing in a warm environment. All participants were tested for thermoregulation and acclimatization, skin and tympanic temperature, heart rate (HR), hormonal status and sweating. The mean skin temperature was the lowest in the control group of subjects exposed to physical exertion under comfortable conditions, and at each point of measurement it was statistically significantly different from that of the other study groups (p < 0.001). Sweating intensity was statistically significantly the lowest in the CTRL group (0.32 ± 0.04 l/m2/h; p < 0.001), compared to all other groups. Cortisol was significantly altered in O group (632.2 ± 92.3; 467.2 ± 89.7), testosterone levels were significantly altered in P (19.2 ± 9.3; 16.4 ± 7.3) and in A groups (22.1 ± 12.4; 14.9 ± 9.9), while prolactin was changed in O (392.1 ± 51.3; 181.4 ± 42.3), P (595.1 ± 191.1; 191.2 ± 52.5), and A group (407.4 ± 189.3; 173.4 ± 43.9) after the experimental period. The impact of acclimatization on hormonal indicators emphasizes its importance in the response of the endocrine system of soldiers to perform military activities in warm climates.

Early embryo losses, progesterone and pregnancy associated glycoproteins levels during summer heat stress in dairy cows.

Objectives of this study were to characterize the effects of heat stress on pregnancy associated glycoproteins (PAG) and progesterone and its involvement in embryo survival. In trial 1, blood samples collected from days 29 to 36 post insemination were examined for the comparison of PAG concentrations between winter (n = 3721) and summer (n = 2388). In trial 2, embryo losses were assessed in winter (n = 144) and in summer (n = 133), in days 31 or 32 of pregnancy. Pregnancy diagnosis was carried out by ultrasonography on days 24 or 25, and it was repeated a week later; in the second occasion PAG concentration was also determined. In trial 3 the PAG and progesterone concentrations were assessed in days 33 to 36 in winter and summer. In trial 1 PAG levels did not differ between winter and summer, the conception rate and the proportion of uncertain pregnancies were higher in winter than summer. The likelihood of pregnancy was 10 to 15% higher in winter. In trial 2, the embryo death rate was higher in summer, but the PAG levels of cows that had embryo loss in summer were higher than those in winter. In both seasons, lower PAG levels were associated with higher risk of pregnancy loss, while embryo death was five times more likely to occur in summer than in winter and lower PAG concentrations were positively associated with higher risk of embryo loss. In trial 3, mean PAG levels were higher and of progesterone were lower during the summer than during the winter. We infer that despite the devastating effects of heat stress on cows' fertility, those early embryos that survive under continuous heat stress can form a well-functioning placenta; hence, the high embryo mortality rate observed during the summer months could be mainly attributed to luteal insufficiency.

Differential expression of miRNAs and related mRNAs during heat stress in buffalo heifers.

The present experiment was aimed to study differential expression of miRNAs and related mRNAs during heat stress (HS) in buffalo heifers. Twelve Murrah buffalo heifers aged between 1.5 and 2.0 years, weighting between 250 and 300 Kg were randomly assigned into two equal groups. The animals were kept in the psychrometric chamber under Thermo-neutral (TN; THI = 72) and HS (THI = 87-90) conditions for 6 h every day between 1000 and 1600 h for 21 days. The blood sampling was done at 1500 h on 15th day of the experiment and physiological parameters viz. pulse rate (PR), respiratory rate (RR) and rectal temperature (RT) were recorded at 1500 h on day -5, -3, -1, 0, +1, +3, +5 with respect to blood sampling. PBMCs were used for extraction of miRNAs and total RNA; and first strand cDNA was synthesized. qPCR was performed for relative gene expression studies. Physiological, hematological (erythrocytic indices), biochemical (triglycerides, urea, ALT, AST, LDH), redox (SOD, ROS) and endocrine parameters (T4) altered significantly (P < 0.05) during HS as compared to TN. Out of eight targeted miRNAs only four were expressed in buffalo heifers. The relative expression of bta-mir-142, bta-mir-1248 and bta-mir-2332 was significantly (P < 0.05) up-regulated whereas expression of bta-mir-2478 was significantly (P < 0.05) down-regulated during HS as compared to TN. The relative expression of the predicted target genes i.e. HSF1, HSP60, HSP70, HSPA8 and HSP90 were significantly (P < 0.05) up-regulated whereas HSF4 expression was significantly (P < 0.05) down-regulated during HS as compared to TN. It can be concluded that a THI of 87-90 could lead to a moderate HS in buffalo heifers. Differential expression studies of miRNAs and related mRNAs in present study deciphers the role of miRNAs in the heat tolerance in buffalo heifers.

Identification of trailer heat zones and associated heat stress in weaner pigs transported by road in tropical climates.

Heat stress is major welfare concern during transport of pigs in tropical climates, which can also lead to direct production costs. This study evaluated the dynamics of heat zones through the load and their relationship with heat stress of weaner pigs during road transport in a tropical climate. Both environmental (e.g. temperature and relative humidity) and physiological (e.g. respiratory frequency and lactate) measures were recorded from four vehicle journeys (70 km distance, 216 weaner pigs within each trailer load) within Ceará, northeastern Brazil. Geostatistics and fluid dynamics simulation techniques were applied to understand the dynamics of heat zones and ventilation patterns the truckload. Statistics based on canonical discriminant analysis and ANOVA were performed to verify the relationship between heat zones and heat stress in pigs. The results showed that, during transport, the generation of heat zones occurred with different magnitudes along the load (P < 0.05), which was harmonized by the ventilation dynamics. There was a heat core with high energy content, in the front region of the lower deck (LD) of the trailer. In this zone, weaners pigs had higher rectal temperature (+1.8 °C temperature difference), respiratory frequency (LD = 94 ± 1.3 breaths/min; UD = 86 ± 1.3 breaths/min), and blood cortisol concentration (LD = 32.9 ± 0.8 ng/mL; UD = 30.18 ± 0.6 ng/mL) (all P < 0.05). Weaners pigs transported in the upper deck (UD) compartments had the highest skin temperature (LD = 38.13 ± 0.3 °C; UD = 38.9 ± 0.22 °C) and the highest mean values of blood lactate (LD = 65.5 ± 1.11 m/M; UD = 71.60 ± 1.19 m/M) and Creatine kinase (LD = 3891.23 ± 69U/L; UD = 4107.43 ± 62U/L) (P < 0.05). Weaners transported in compartments of the LD of trailer were more susceptible to heat stress, while weaners in the UD compartments were more susceptible to physical stress and muscle exhaustion. These results provide additional evidence of heat zones within trailer compartments and highlight the requirement for the planning of pig transport operations in tropical climates to mitigate risks of heat stress.

Thermal stress causes oxidative stress and physiological changes in female rabbits.

The present study investigated the effects of heat stress on oxidative stress status and physiological changes using female New Zealand White rabbits. 24 sexually mature female rabbits weighing 1953.1-2375.4 g were divided into 4 groups of 6 animals each and subjected to ambient temperature (T0: 19-26 °C), 27-28 °C for T1, 31-32 °C for T2 and 35-36 °C for T3 using electrical heaters from 8:00 a.m. to 4:00 p.m. daily for 30 days. Feed intake and body weight gain were recorded daily. Behavioral alterations of anxiety, dizziness, aggression, withdrawal, impaired feed intake were observed. At the end of experimental period animals were sacrificed, blood samples and vital organs such as liver, kidney, heart, ovaries, uterus collected for appropriate analysis. Results revealed that animals of T2 and T3 had an 11% decrease in the final body weights and 62% body weight gain but increase in feed conversion ratio by 64.81%, 24.19% water intake, 3.64% in rectal and 2.42% in skin temperature compared to the control. Dizziness, withdrawal to a corner of the cage and reduced feed intake were observed. The live weight of lungs and kidneys increased by 37.71% and 33.78% while that of ovaries and uterus decreased in the same animals of T2 and T3. Animals from T2 and T3 showed significant decrease (p < 0.05) by 23.64% in hemoglobin concentration, 12.73% in red blood cells, 11.93% in packed cell volume, 12.02% in total protein while mean corpuscular volume, white blood cells, lymphocytes, creatinine, urea and aspartate transaminase increased respectively by 10.73%, 42.37%, 15.53%, 28.98%, 53.2% and 23.31% compared to the control. The kidney level of malondialdehyde was significantly increased in T2 and T3 animals by 74.29%, whereas protein, catalase, superoxide dismutase and glutathione peroxidase activity were significantly lower (p < 0.05) compared with control. It was concluded that long-term exposure of female rabbits to elevated ambient temperatures induces heat stress and accompanying oxidative stress that consequently impairs physiological function.

Adaptogenic potential of royal jelly in reproductive system of heat stress-exposed male rats.

Testicular heat stress (HS) can lead to testicular tissue destruction and spermatogenesis disturbances. Royal Jelly (RJ) has been introduced as a potent antioxidant. We investigated the effects of RJ on testicular tissue, oxidative stress and sperm apoptosis in HS-exposed rats. Compared to HS-exposed groups, RJ co-treatment could improve testosterone reduction and histopathological damages. The RJ co-administration decreased MDA level in testicular tissue, while TAC and CAT levels were remarkably increased compared to HS-exposed groups. Moreover, significant higher expression level of Bcl-2 and lower expression levels of P53 and Caspase-3 were seen following RJ co-administration compared to HS-exposed groups. Our data suggest that RJ can effectively ameliorate experimental HS-induced testiculopathies in rats through testicular antioxidant defense system restoration and germ cells apoptosis regulation.

Acute kidney injury and workload in a sample of California agricultural workers.

BACKGROUND: Kidney damage is associated with an increased workload in high ambient temperatures and may represent a pathway to chronic kidney disease of unknown origin in agricultural workers. We tested the associations of workload and heat with acute kidney dysfunction in California agricultural workers. METHODS: We recruited a convenience sample of 471 agricultural workers from 29 farms in California during two summer harvest seasons. The sustained 3-minute maximum workload was estimated using accelerometer data collected from Actical monitors and individual heat load through elevations in core body temperature. Acute kidney injury (AKI) was defined by a change in serum creatinine of ≥0.3 mg/dL or ≥1.5 times the preshift creatinine over the course of the work shift. Associations between AKI and workload were modeled using logistic regression, controlling for demographic, physiologic, and occupational variables. RESULTS: Of the total, 357 workers (75.8%) had accelerometer readings in the moderate workload category, 93 (19.7%) had readings in the vigorous category. 177 (36%) had elevations of core body temperature ≥1°C; 72 workers (14.9%) demonstrated evidence of AKI after a single day of agricultural work. The workload category was associated with an increased adjusted odds of AKI (1.92; 95% confidence interval, 1.05-3.51). Piece-rate work was also associated with increased adjusted odds of AKI (3.02; 95% CI, 1.44-6.34). CONCLUSIONS: Heavy occupational workload and piece-rate work were associated with acute effects on the renal health of agricultural workers. This indicates that occupations requiring high physical effort put workers at risk for AKI, possibly independent of ambient and core body temperature. Changes to agricultural practices may reduce the risk of renal disorders for these workers.

The effect of heat stress on hematological parameters and oxidative stress among bakery workers.

Heat stress causes physiological changes, and changes in hematological parameters and hormonal levels in the human body, known as thermal strain. This study was conducted to determine the effect of exposure to heat stress on hematological parameters and oxidative stress in the bakers of Shahroud City, Iran. A total of 163 bakery workers (exposed group) and 135 office workers (unexposed group) with a minimum of 1-year working experience were selected. Exposure to heat stress was measured using ISO-7243 criteria on the hottest days of the year (late July and August). Wet-bulb globe temperature (WBGT) was calculated based on indoor environments. Oxidative stress indices including malondialdehyde (MDA), nitric oxide (NO), total antioxidant capacity (TAC) in the bakers' and office workers' serum and hematological parameters were measured. Statistical analysis was done through independent t-test, and multivariate linear regression using SPSS v24. Analysis of hematological parameters showed that about 70% and 68% of the bakers had abnormal mean cell volume (MCV) and white blood cell (WBC) count, respectively, while only around 12% of them had abnormal mean cell hemoglobin concentration (MCHC). The counts of red blood cells (RBC), WBC, lymphocytes (LYM), and MCV showed significant differences in different occupational groups (p < 0.05). The levels of MDA and NO were significantly higher in bakers with WBGT more than the threshold value (p < 0.05). The WBGT index for assessing heat stress can be used as a predictor variable for MDA and NO levels. In addition, heat stress exposure could be a risk factor for abnormal WBC, RBC, LYM, and MCV.

Effect of heat stress on superoxide anion production in native and crossbred cattle under in vitro whole blood culture model.

Impact of global warming on the dairy industry has gained attention due to huge economic losses through low production and fertility caused by heat stress. Exposure to hyperthermia provokes a series of complex responses in mammals which are been related to morphological and physiological alterations including the production of reactive oxygen species (ROS). A quantitative spectrophotometric based nitroblue tetrazolium (NBT) reduction assay was used to estimate the superoxide anion (•O2-) level in heat stressed (at 42 °C) whole blood cultures of native and crossbred bulls (Sahiwal and Frieswal), in vitro. The breed effect in the kinetics of •O2- production at different time periods of continual heat stress was analyzed by repeated measures ANOVA. Comparison between different time periods in reference to 37 °C was analyzed by paired t-test. The •O2- level was significantly different (p < 0.05) between cells at 37 °C and 42 °C at different periods of incubation. Kinetics study showed increment of •O2- production on the acute phase of stress followed by a reduction in both Sahiwal and Frieswal breeds. In Sahiwal breed, the inflated superoxide level continued abated till 4 h and raised again at 6 h, while in Frieswal •O2- level reverted to raise sooner with in 2 h of incubation itself. Contrarily, kinetic of •O2- level in plasma showed a significant reduction (p < 0.001) at 30 min of 42 °C incubation followed by increment of •O2- level. Further, the breed variation was significant (p < 0.05) and a significant high reduction of •O2- level was observed in Sahiwal breed. Our finding indicates that, a better and longer •O2- production homeostasis and higher plasma scavenging ability of native breed may be one of the reasons for the higher thermal tolerance of these breeds in tropical climate.

Ameliorative effects of L-glutamine on haematological parameters in heat-stressed Red Sokoto goats.

The aim of the study was to evaluate haematological responses in Red Sokoto goats (RSGs) administered with L-glutamine during the hot-dry season. Experimental animals included 28 clinically healthy RSGs divided into treated group (n = 14); each administered L-glutamine at 0.2 g/kg body weight, dissolved in 10 mL distilled water, and control group (n = 14); each administered 10 mL distilled water, per os once daily for 21 days. The ambient temperature and relative humidity recorded daily for 4 weeks were used to calculate the temperature-humidity index. Three millilitres of blood sample was collected from each goat by jugular venipuncture for haematology, while rectal temperature (RT), heart rate (HR) and respiratory rate (RR) were also measured once weekly at weeks 0 (before), 1, 2, 3 (during) and 4 (after L-glutamine administration). The haematological, RT, HR and RR data obtained weekly were analysed using repeated-measures one-way ANOVA, followed by Tukey's post-hoc test to evaluate differences between periods, and between treated and control groups. The PCV, haemoglobin concentration and RBC count were higher (P < 0.05) in the treated group compared to the control group during the period of L-glutamine administration. These differences were sustained till week 4. Beginning from week 1 of the study, the total leucocyte count in treated group (10.10 ± 0.25 × 103/µL) was higher (P < 0.05) than the count in control group (7.23 ± 0.41 × 103/µL), this trend was also maintained throughout the study. The neutrophil:lymphocyte ratio during weeks 3 and 4 of the experiment was lower (P < 0.05) in the treated compared to the control group. RT was lower (P < 0.05) in treated group than the control group. In conclusion, L-glutamine administration ameliorated the adverse effects of heat stress on the haematological parameters in RSGs during the hot-dry season.

Physiological and molecular responses to thermal stress in red cusk-eel (Genypterus chilensis) juveniles reveals atrophy and oxidative damage in skeletal muscle.

The red cusk-eel (Genypterus chilensis) is a native species with strong potential to support Chilean aquaculture diversification. Environmental stressors, such as temperature, may generate important effects in fish physiology with negative impact. However, no information exists on the effects of thermal stress in Genypterus species or how this stressor affects the skeletal muscle. The present study evaluated for the first time the effect of high temperature stress in red cusk-eel juveniles to determine changes in plasmatic markers of stress (cortisol, glucose and lactate dehydrogenase (LDH)), the transcriptional effect in skeletal muscle genes related to (i) heat shock protein response (hsp60 and hsp70), (ii) muscle atrophy and growth (foxo1, foxo3, fbxo32, murf-1, myod1 and ddit4), and (iii) oxidative stress (cat, sod1 and gpx1), and evaluate the DNA damage (AP sites) and peroxidative damage (lipid peroxidation (HNE proteins)) in this tissue. Thermal stress generates a significant increase in plasmatic levels of cortisol, glucose and LDH activity and induced heat shock protein transcripts in muscle. We also observed an upregulation of atrophy-related genes (foxo1, foxo3 and fbxo32) and a significant modulation of growth-related genes (myod1 and ddit4). Thermal stress induced oxidative stress in skeletal muscle, as represented by the upregulation of antioxidant genes (cat and sod1) and a significant increase in DNA damage and lipid peroxidation. The present study provides the first physiological and molecular information of the effects of thermal stress on skeletal muscle in a Genypterus species, which should be considered in a climate change scenario.

Dietary enzymatically-treated Artemisia annua L. supplementation could alleviate oxidative injury and improve reproductive performance of sows reared under high ambient temperature.

The medicinal plant Artemisia annua L. is well known for its antimalarial compound artemisinin and the antioxidant capacity of its active ingredients. However, low bioavailability of Artemisia annua L. limits its therapeutic potential, fermentation of Artemisia annua L. can improve its bioavailability. This study was aimed to investigate the effects of dietary supplementation of enzymatically-treated Artemisia annua L. (EA) on reproductive performance, antioxidant status, milk composition of heat-stressed sows and intestinal barrier integrity of their preweaning offspring. 135 multiparous sows of average parity 4.65 (Landrace × large white) at day 85 of pregnancy were randomly distributed into 3 treatments. Sows in the control group were housed at control rooms (temperature: 27.12 ± 0.18 °C, temperature-humidity index (THI): 70.90 ± 0.80) and fed the basal diet. Sows in the HS, HS + EA groups were fed the basal diet supplemented with 0 or 1.0 g/kg EA respectively, and reared at heat stress rooms (temperature: 30.11 ± 0.16 °C, THI: 72.70 ± 0.60). Heat stress increased the malondialdehyde (MDA) content, reduced the activities of total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD) of sows and piglets, and seriously compromised the antioxidant capacity of the sows and the intestinal integrity of their offspring. However, dietary supplementation of 1.0 g/kg EA reduced the MDA content, increased the activities of T-SOD and T-AOC in serum, colostrum, and milk of heat-stressed sows, and increased colostrum yield and 14-d milk fat content. EA supplementation also increased piglet weaning weight and the activities of T-SOD and T-AOC in serum. In addition, the abundances of intestinal tight junction proteins claudin-1 and occludin were up-regulated in piglets in EA-supplemented group. In conclusion, dietary EA supplementation at 1.0 g/kg can alleviate the oxidative stress in heat-stressed sows, improve the antioxidant capacity in both sows and their offspring, and promote the intestinal barrier integrity in their offspring. EA may be a potent dietary supplement that ameliorates oxidative stress in livestock production by improving the antioxidant capacity.

Supplementation of Moringa oleifera leaf powder orally improved productive performance by enhancing the intestinal health in rabbits under chronic heat stress.

Heat stress jeopardizes animal's growth and health mainly through induction of oxidative stress and inflammation. The current study investigated the effects of Moringa oleifera leaf powder (MOLP) supplementation on productive performance and intestinal health of rabbits under chronic heat stress (HS). Young New Zealand White rabbits (male) at the age of 32 weeks (n = 21, mean body weight of 3318 ± 171 g) for four weeks' period were reared on commercial pelleted diet and divided into three groups: control (CON, 25 °C), HS (35 ± 1 °C) and HS (35 ± 1 °C) with MOLP (HSM) supplemented orally (200 mg/kg body weight). The results demonstrated that rabbits in the HSM group had reduced rectal temperature, respiration rate and improved FCR due to improved daily gain and better crude fiber (NDF) digestibility (P < 0.05) compared with HS group. MOLP improved intestinal integrity and function as indicated by lower serum diamine oxidase level and increased jejunal weight, length, villus height and ratio of villus height to crypt depth than heat-stressed rabbits. MOLP reversed the increased levels of serum cortisol, metabolic indicators i.e. glucose, insulin, and reduced concentrations of serum triiodothyronine. MOLP supplementation also significantly down-regulated the mRNA expression of tumor necrosis factor alpha (α), heat shock protein A2, glutathione peroxidase-1, interleukin (IL)-1α and increased the expression of IL-6. In conclusion, MOLP supplementation could enhance intestinal health along with production and metabolic indicators by alleviating the oxidative stress and inflammatory response in small intestine of hyper-thermic rabbits.

Hydration Status and Kidney Health of Factory Workers Exposed to Heat Stress: A Pilot Feasibility Study.

Dehydration associated with heat stress increases the risk of workplace injury or illness, decreases productivity, and may contribute to the chronic kidney disease epidemic identified in outdoor workers from hot climates. There is limited research on the effects of chronic occupational heat stress among indoor workers. We aimed to test the feasibility of measuring markers of hydration and kidney function in foundry factory workers in Southern Brazil, exposed and not exposed to heat stress. Factory workers exposed to heat stress (wet bulb globe temperature ≥28.9) and not exposed to heat were identified by management and invited to participate. Clinical and biochemical markers of hydration and kidney function were evaluated before and after a single 8.5 h work shift (lunch time not included). Feasibility outcomes included rates of enrolment, % completion of study protocols, and time to complete data collection. This study was deemed feasible with 80% enrolment and 90% completion of the protocol. Among the preselected workers, the enrolment rate was 91%. All subjects completed the physiological measures and blood collection and 95% completed the urine studies. Mean time to complete data collection pre-shift was 19.1 ± 4.2 min and post-shift: 14.3 ± 4.0 min. Workers exposed to heat stress had a greater decline in estimated glomerular filtration rate compared to controls over the work shift (-13 ± 11 vs. -5 ± 7 mL/min; p < 0.01). We demonstrated the feasibility and challenges of conducting future hydration and kidney function research among indoor factory workers. Further study is needed to determine if exposure to indoor heat contributes to a decline in kidney function.

Thermal stress causes nuclear and cellular abnormalities of peripheral erythrocytes in Indian major carp, rohu Labeo rohita.

Rise of water temperature as a consequence of global warming is anticipated to affect the physiological activities of fish, especially in tropical regions. In the present experiment, we exposed the Indian major carp, rohu Labeo rohita to three different temperature regimes (30 °C as control and 33 °C and 36 °C) for 60 days and observed the effects of these temperature on: major hemato-biochemical indices (Hemoglobin; Hb, Red blood cell; RBC, White blood cell; WBC and blood glucose levels), erythrocytic nuclear abnormalities (ENA), and erythrocytic cellular abnormalities (ECA) of peripheral erythrocytes along with the formation of differential leucocytes in the blood. Fish were sacrificed at day 7, 15, 30 and 60 after the start of exposure to the temperature regimes. Hb decreased significantly on days 7 and 15 at 36 °C. Throughout the study period, the decrease of RBC and increase of WBC were significant at 36 °C. Blood glucose level increased significantly initially at day 7 but decreased significantly at day 60 at 36 °C. Frequencies of ENA (binucleated, nuclear bud, nuclear bridge, karyopyknosis and notched nuclei) and ECA (twin, fusion, echinocytic, spindle, tear drop and elongated shaped) were significantly increased at the highest temperature (36 °C) at almost all of the sampling days. In the case of differential leucocyte count, high temperature caused a significant increase in the number of neutrophils and a significant decrease in the number of lymphocytes. Overall, these results indicate that chronic exposure to high temperature (36 °C) induces a number of stress responses in rohu and that temperature should be kept below 36 °C in the aquaculture setting to avoid damage to the fish.

Benefits of the inclusion of açai oil in the diet of dairy sheep in heat stress on health and milk production and quality.

The objective of this study was to determine whether the addition of açai (Euterpe oleracea) oil in the diets of lactating sheep under heat stress exerted beneficial effects on health as well as milk production and quality. Eighteen multiparous Lacaune sheep (2 or 3 parities; 28-30 days of lactation; average milk production of 1.7 L/sheep/day) were stratified by parity and milk production and were assigned randomly to 1 of 2 treatments (9 sheep/treatment): diet supplemented with 2% of soybean oil (SOY) or 2% of açai oil (AÇAI) in the concentrate for 14 days. The amount of oil added in the diet was equivalent to 0.65% of the total diet (dry matter basis). Blood and milk samples were collected on days 1, 10 and 14. On day 14, the AÇAI group sheep had lower serum concentrations of leukocytes, neutrophils, and lymphocytes than did the SOY group sheep. On day 14, AÇAI group sheep had lower serum concentration of triglycerides and urea, milk concentration of fat and total solid and milk lipid peroxidation than did SOY group sheep. However, on day 14, AÇAI group sheep had higher serum concentrations of glucose and globulin, serum and milk antioxidant capacity against peroxyl radicals, milk production and productive efficiency than did SOY group sheep. The fatty acids profile in milk did not differ between groups. These data suggest that açai oil improved the antioxidant activity in serum and milk and improved milk production and quality in dairy sheep under heat stress.

Stress biomarkers and proteomics alteration to thermal stress in ruminants: A review.

Heat stress may adversely affect physiochemical and immune responses of livestock and alter biological functions. The comfort or thermoneutral zone for livestock, which has long been a subject of research, mainly depends on species, breed, and health. Heat stress is associated with impaired livestock productivity due to reductions in feed intake, growth rates and immunity and changes in blood constituents and biological pathways. In ruminants, elevated temperatures have deleterious consequences on protein synthesis. Exposure of ruminant animals to elevated temperatures may induce release of heat shock proteins (HSPs); HSPs usually enter the blood circulation during tissue damage and causes cell necrosis or death. Additionally, hyperthermia is associated with augmented production of cellular reactive oxygen species (ROS), which cause protein degradation and further decrease protein synthesis by preventing protein translation. Moreover, it has been suggested that high environmental temperatures lead to increased inflammatory signalling in tissues via activation of the nuclear factor kappa B (NF-κB) and tumor necrosis factor alpha (TNF-α) pathways as well as via alteration of skin colour gene (melanocortin 1 receptor (MC1R) and premelanosome protein (PMEL)) expression. Previous proteomics analyses have suggested that heat stress can reduce adenosine triphosphate (ATP) synthesis, alter gluconeogenesis precursor supply, and induce lipid accumulation in the liver with subsequent disturbance of liver structure. This review focuses on the scientific evidence regarding the impact of heat stress on immune and inflammatory responses, antioxidant status, stress biomarkers, skin colour gene (PMEL and MC1R) expression and proteomic profiles in ruminants.

Effects of dietary curcumin and acetylsalicylic acid supplements on performance, muscle amino acid and fatty acid profiles, antioxidant biomarkers and blood chemistry of heat-stressed broiler chickens.

The objective was to investigate the effects of dietary curcumin and acetylsalicylic acid (ASA) on the performance and physiological responses of broiler chickens under chronic thermal stress. One hundred and sixty day-old male chicks (Ross 308) were divided equally into 4 groups (each contained 4 replicates). On the day 22 of age and thereafter, the first group (TN) was raised in a thermoneutral condition (23 ±â€¯1 °C), while the second group (HS) was subjected to 8 h of thermal stress (34 °C) and both groups fed the basal diet with no supplements. The third (CR) and fourth (AS) groups were subjected to the same thermal stress conditions and fed curcumin-supplemented diet (100 mg curcumin kg-1 diet) and ASA-supplemented diet (1 g ASA kg-1 diet), respectively. Dietary treatment had a significant effect on ADFI (P = 0.041), average daily gain (P = 0.013) and final body weight (P = 0.001). The curcumin-supplemented had higher values for these measures compared with other experimental groups (P < 0.05). Also, the dietary curcumin supplement significantly increased the carcass yield as compared to the HS group (P < 0.05). Compared with the HS group, the dietary curcumin and ASA supplements decreased the concentration of malondialdehyde in the breast muscles (P = 0.014). Both dietary supplements exhibited a marked ability to restore the serum TAC, Na and K in heat-stressed broiler chickens. The current study reported a remarkable ability of curcumin supplement to restore the concentrations of polyunsaturated fatty acids (PUFA) in the breast muscles of heat-stressed broilers, including α-linolinec acid and Docosahexaenoic acid (P = 0.009 and 0.001, respectively). It could be concluded that supplemental dietary curcumin or ASA enhanced growth performance and antioxidant biomarkers of heat-stressed broilers. Moreover, curcumin might be an effective dietary supplement to alleviate the adverse effect of chronic thermal stress on carcass yield and meat quality.