Heat-Shock Proteins Gene Expression in Peripheral Blood Mononuclear Cells as an Indicator of Heat Stress in Beef Calves

In-depth transcriptome profiling of Cherry Valley duck lungs exposed to chronic heat stress

Amidst rising global temperatures, chronic heat stress (CHS) is increasingly problematic for the poultry industry. While mammalian CHS responses are well-studied, avian-specific research is lacking. This study uses in-depth transcriptome sequencing to evaluate the pulmonary response of Cherry Valley ducks to CHS at ambient temperatures of 20°C and a heat-stressed 29°C. We detailed the CHS-induced gene expression changes, encompassing mRNAs, lncRNAs, and miRNAs. Through protein-protein interaction network analysis, we identified central genes involved in the heat stress response-TLR7, IGF1, MAP3K1, CIITA, LCP2, PRKCB, and PLCB2. Subsequent functional enrichment analysis of the differentially expressed genes and RNA targets revealed significant engagement in immune responses and regulatory processes. KEGG pathway analysis underscored crucial immune pathways, specifically those related to intestinal IgA production and Toll-like receptor signaling, as well as Salmonella infection and calcium signaling pathways. Importantly, we determined six miRNAs-miR-146, miR-217, miR-29a-3p, miR-10926, miR-146b-5p, and miR-17-1-3p-as potential key regulators within the ceRNA network. These findings enhance our comprehension of the physiological adaptation of ducks to CHS and may provide a foundation for developing strategies to improve duck production under thermal stress.

The Effect of Subclinical Ketosis on the Peripheral Blood Mononuclear Cell Inflammatory Response and Its Crosstalk with Depot-Specific Preadipocyte Function in Dairy Cows

During the periparturient period, cows undergo heightened energy demands at lactation onset, paired with reduced dry matter intake, leading to negative energy balance (NEB). Excessive lipolysis-driven adipose tissue remodeling, triggered by NEB, significantly contributes to ketosis in periparturient dairy cows. However, the role of peripheral blood mononuclear cells (PBMCs) in the pathogenesis of ketosis and in modulating adipose tissue function remains poorly understood. Here, we investigated how ketosis affects the transcriptional profile and secretome of PBMCs and its influence on preadipocyte function in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). Twenty-one postpartum Holstein dairy cows were categorized as either subclinical ketosis (SCK; BHB ≥ 1.0 mM) or control (CON; BHB < 0.8 mM) based on blood beta-hydroxybutyrate (BHB) concentration screening. Blood samples were collected intravenously for the isolation of PBMCs and serum metabolic profiling. Ketosis elevated circulating NEFA and BHB levels but reduced total WBC and neutrophil counts. Isolated PBMCs were evaluated for gene expression and used to produce conditioned media (PBMC-CM), during which PBMCs were stimulated with 10 ng/mL LPS. The overall phenotype of PBMCs was largely consistent between SCK and CON cows, with minimal differences detected in immunomodulatory cytokine expression and PBMC-CM composition following stimulation. Preadipocytes isolated from non-ketotic cows were treated with PBMC-CM to assess the effect of PBMC secretomes on adipose cell function. Preadipocytes treated with SCK PBMC-CM showed reduced lipid accumulation compared to those treated with CON PBMC-CM regardless of the depot. SAT preadipocytes had heightened expression of lipid metabolism-related genes, including DGAT1, LIPE, and FASN, compared to VAT when treated with SCK PBMC-CM. Preadipocytes treated with CM from PBMC stimulated by LPS exhibited upregulation in IL1B and IL6 regardless of the depot or source of PBMCs. Together, these results indicate that although PBMC profiles showed minimal differences, preadipocytes treated with PBMC-CM may be influenced by additional factors, leading to altered preadipocyte function and gene expression that may contribute to adipose cellular dysfunction.

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 HSP90AA1 gene is involved in heat stress responses and its functional genetic polymorphisms are associated with heat tolerance in Holstein cows

As the stress-inducible isoform of the heat-shock protein 90 (HSP90), the HSP90AA1 gene encodes HSP90α and plays an important role in heat stress (HS) response. Therefore, this study aimed to investigate the role of the HSP90AA1 gene in cellular responses during HS and to identify functional SNPs associated with thermotolerance in Holstein cattle. For the in vitro validation experiment of acute HS, cells from the Madin-Darby bovine kidney cell line were exposed to 42°C for 1 h, and various parameters were assessed, including cell apoptosis, cell autophagy, and the cellular functions of HSP90α by using its inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). Furthermore, the polymorphisms identified in the HSP90AA1 gene and their functions related to HS were validated in vitro. Acute HS exposure induced cell apoptosis, cell autophagy, and upregulated expression of the HSP90AA1 gene. Inhibition of HSP90α by 17-AAG treatment had a significant effect on the expression of the HSP90α protein and increased cell apoptosis. However, autophagy decreased in comparison to the control treatment when cells were exposed to 42°C for 1 h. Five SNPs identified in the HSP90AA1 gene were significantly associated with rectal temperature and respiration score in Holstein cows, in which the rs109256957 SNP is located in the 3' untranslated region (3' UTR). Furthermore, we demonstrated that the 3' UTR of HSP90AA1 is a direct target of bta-miR-1224 by cell transfection with exogenous microRNA (miRNA) mimic and inhibitor. The luciferase assays revealed that the SNP rs109256957 affects the regulation of bta-miR-1224 binding activity and alters the expression of the HSP90AA1 gene. Heat stress-induced HSP90AA1 expression maintains cell survival by inhibiting cell apoptosis and increasing cell autophagy. The rs109256957 located in the 3' UTR region is a functional variation and it affects the HSP90AA1 expression by altering its binding activity with bta-miR-1224, thereby associating with the physiological parameters of Holstein cows.

Importance of dietary supplementation of soluble and insoluble fibers to sows subjected to high ambient temperatures during late gestation and effects on lactation performance

Heat stress adversely affects sows' performance, which can be improved by applying proper nutritional strategies. This study was conducted to investigate the interactive effects of dietary fiber levels and sources on sows' reproductive performance, metabolic response during gestation, and the carry-over influence on litter performance in the lactation period during heat stress (average room temperature of 27.1 °C). Fifty-four multiparous sows (Landrace × Yorkshire; initial body weight of 236.3 ± 16 kg; 2, 3 and 4 parities) at d 90 of gestation were assigned to a 2 × 3 factorial arrangement (9 sows/treatment), involving 2 dietary fiber levels (4.5% and 6% crude fiber) and 3 dietary fiber sources (wheat bran [WB], palm kernel meal [PK], and beet pulp [BP]). Sows fed the BP diet had highest (P < 0.01) feed intake and constipation index and lowest (P < 0.01) farrowing duration. Piglet weight (P = 0.041) and litter weight (P < 0.01) at weaning were higher in sows in the BP treatment compared to PK treatment. Sows in the BP treatment showed the greatest (P < 0.01) digestibility of crude protein and neutral detergent fiber. The fecal concentration of acetate was the lowest (P < 0.01) in the PK treatment. Total short-chain fatty acid production was increased in the WB and BP treatments compared with the PK. Sows in the BP treatment showed the lowest (P = 0.036) hair cortisol. The blood insulin concentration of sows was higher (P = 0.026) in the high fiber (6%) treatment compared with the low fiber (4.5%) treatment at 90 min and 120 min after the meal. The concentration of phthalic acid, succinic acid, phenylethylamine, hydrocinnamic acid, iron, linoleic acid, glycerol, ketone, and formamide were increased (P < 0.05) in the BP treatment compared with the WB. The BP treatment with high soluble fiber content improved the constipation index, farrowing duration, and litter performance, while high insoluble fibers increased sows comfort and reduced stress factors including respiratory rate and rectal temperature. Therefore, both soluble and insoluble sources of fiber are necessary to be added to the diet of gestating sows.

Influence of Heat Stress on Body Surface Temperature and Blood Metabolic, Endocrine, and Inflammatory Parameters and Their Correlation in Cows

This study aimed to determine whether heat stress affected the values and correlations of metabolic, endocrinological, and inflammatory parameters as well as the rectal and body surface temperature of cows in the early and middle stages of lactation. This experiment was conducted in May (thermoneutral period), June (mild heat stress), and July (moderate to severe heat stress). In each period we included 15 cows in early lactation and 15 in mid-lactation. The increase in rectal and body surface temperatures (°C) in moderate to severe heat stress compared to the thermoneutral period in different regions was significant (p < 0.01) and the results are presented as mean and [95%CI]: rectal + 0.9 [0.81-1.02], eye + 6 [5.74-6.25], ear + 13 [11.9-14.0], nose + 3.5 [3.22-3.71], forehead + 6.6 [6.43-6.75], whole head + 7.5 [7.36-7.68], abdomen + 8.5 [8.25-8.77], udder + 7.5 [7.38-7.65], front limb + 6 [5.89-6.12], hind limb + 3.6 [3.46-3.72], and whole body + 9 [8.80-9.21]. During heat stress (in both mild and moderate to severe stress compared to a thermoneutral period), an increase in the values of extracellular heat shock protein 70 (eHsp70), tumor necrosis factor α (TNFα), cortisol (CORT), insulin (INS), revised quantitative insulin sensitivity check index (RQUICKI), urea, creatinine, total bilirubin, aspartate transpaminase (AST), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), and creatin kinase (CK) occurred, as well as a decrease in the values of triiodothyronine (T3), thyroxine (T4), non-esterified fatty acids (NEFA), glucose (GLU), β-Hydroxybutyrate (BHB), calcium, phosphorus, total protein (TPROT), albumin (ALB), triglycerides (TGCs), and cholesterol (CHOL). In cows in early lactation compared to cows in mid-lactation, there was a significantly larger increase (p < 0.01) in the values of eHsp70, TNFα, GLU, RQUICKI, and GGT, while the INS increase was smaller during the three experimental periods. The decrease in the values of Ca, CHOL, and TGC was more pronounced in cows in early lactation compared to cows in mid-lactation during the three experimental periods. Rectal temperature was related to eHsp70 (r = 0.38, p < 0.001) and TNFα (r = 0.36, p < 0.01) and showed non-significant poor correlations with other blood parameters. Blood parameters correlate with body surface temperature, with the following most common results: eHsp70 and TNFα showed a moderately to strongly significant positive correlation (r = 0.79-0.96, p < 0.001); CORT, INS, and Creat showed fairly to moderately significant positive correlations; T3, T4, NEFA and GLU showed fairly to moderately significant negative correlations (r = 0.3-0.79; p < 0.01); RQUICKI, urea, AST, and GGT showed fairly and significantly positive correlations; and TGC, CHOL, TPROT, and ALB showed fairly and significantly negative correlations (r = 0.3-0.59; p < 0.01). Measuring the surface temperature of the whole body or head can be a useful tool in evaluating the metabolic response of cows because it has demonstrated an association with inflammation (TNFα, eHsp70), endocrine response (CORT, T3, T4), the increased use of glucose and decreased use of lipids for energy purposes (INS, NEFA, GLU, and RQUICKI), and protein catabolism (ALB, TPROT, urea, Creat), which underlies thermolysis and thermogenesis in cows under heat stress. In future research, it is necessary to examine the causality between body surface area and metabolic parameters.

Association of heat-shock protein 70.1 gene with physiological and physical performance of Bali cattle

Background and Aim

Global warming challenges cattle productivity and welfare since it affects heat stress and scarce feed. The heat-shock protein 70 (HSP70) gene is essential in cytoprotection against stressors, protecting cells from dysregulated gene expression and apoptosis. This study aimed to identify significant genetic markers of the HSP70.1 gene that can be leveraged genetically to enhance thermotolerance and production in Bali cattle further.

Materials and Methods

Animals were sampled from three different rearing systems. In this study, 83 healthy adult male Bali cattle without abnormalities were utilized. Single-nucleotide polymorphism (SNP) diversity associated with the physiological and physical traits of Bali cattle was assessed using SNPStat online software. Gene expression for putative SNPs and their genotypic groups was further evaluated.

Results

There were 15 polymorphic SNPs (c.-185G>A, c.-69T>G, c.10G>C, c.19A>G, c.45C>T, c.101INS, c.115T>C, c.130T>C, c.136G>T, c.159G>C, c.164G>T, c.234G>A, c.303G>A, c.333C>A, and c.456C>T) identified, of which 12 were associated with the assessed trait. Nine SNPs were associated with physiological traits, while eight were with physical traits. The c.136G>T as a novel, high minor allele frequency, and associative SNP was selected for HSP70 gene expression. Individuals with the TT genotype have a trim physique, susceptible physiology, and high HSP70 mRNA expression. On the other hand, the GG genotype was significantly associated with larger physique, lower physiology, and low HSP70 mRNA expression. The higher expression may indicate that HSP70.1 is involved in mitigating the deleterious effects of stress. As a result, the animal experienced negative energy balance, decreasing body size.

Conclusion

Single-nucleotide polymorphism c.136G>T is a candidate biomarker for heat resistance traits in Bali cattle.

Effects of heat stress on performance, physiological parameters, and blood profiles of early-fattening Hanwoo steers in climate chambers

OBJECTIVE

This study was conducted to assess effects of heat stress on growth performance, physiological parameters, and blood profiles of Hanwoo steers during early-fattening period in climate chambers.

METHODS

Four Hanwoo steers (body weight, 454.3±10.9 kg; age, 14±0.1 month) were allocated into four levels of temperature-humidity index (THI) in a 4×4 Latin square design for 21 days (pre-adaptation, 7 d; heat stress, 7 d; post-adaptation, 7 d) per period. Experimental treatments were assigned according to THI chart based on National Institute Animal Science (NIAS, 2022): Comfort (25.5°C to 26.5°C, 60%; THI 73 to 75), Mild (28°C to 29°C, 60%; THI 77 to 79), Moderate (29.5°C to 30.5°C, 80%; THI 82 to 84), and Severe (31°C to 32°C, 80%; THI 85 to 86) in separate climatic controlled chambers.

RESULTS

The dry matter intake (DMI) of the formula feed was lower in Severe compared to Mild and Comfort (p<0.05). The DMI of rice straw was the lowest in Severe and lower in Moderate than Comfort and Mild (p<0.05). Both average daily gain and feed conversion ratio of Severe and Moderate were lower than those of Mild and Comfort (p<0.05). Water intake was the highest in Severe and lower in Moderate compared with Comfort and Mild (p<0.05). Heart rate and rectal temperature increased as THI level increased (p<0.05). Glucose was the lowest in Severe and lower in Moderate compared to Comfort (p<0.05). On the contrary, non-esterified fatty acid was the highest in Severe and lower in Moderate compared with Comfort (p<0.05). Blood urea nitrogen of Moderate and Severe were higher than those of Comfort and Mild (p<0.05). Cortisol increased as THI increased (p<0.05).

CONCLUSION

This study demonstrated the negative effects of heat stress on the performance and physiological responses of Hanwoo steers during the early-fattening period. In addition, it is judged that the THI chart for Hanwoo steers of National Institute of Animal Science (2022) was properly calculated.

Heat stress adaptation in cows - Physiological responses and underlying molecular mechanisms

Heat stress is a key abiotic stressor for dairy production in the tropics which is further compounded by the ongoing climate change. Heat stress not only adversely impacts the production and welfare of dairy cows but severely impacts the economics of dairying due to production losses and increased cost of rearing. Over the years, selection has ensured development of high producing breeds, however, the thermotolerance ability of animals has been largely overlooked. In the past decade, the ill effects of climate change have made it pertinent to rethink the selection strategies to opt for climate resilient breeds, to ensure optimum production and reproduction. This has led to renewed interest in evaluation of the impacts of heat stress on cows and the underlying mechanisms that results in their acclimatization and adaptation to varied thermal ambience. The understanding of heat stress and associated responses at various level of animal is crucial to device amelioration strategies to secure optimum production and welfare of cows. With this review, an effort has been made to provide an overview on temperature humidity index as an important indicator of heat stress, general effect of heat stress in dairy cows, and impact of heat stress and subsequent response at physiological, haematological, molecular and genetic level of dairy cows.

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.

Exploring the impact of temporal heat stress on skeletal muscle hypertrophy in bovine myocytes

The primary aim of this investigation was to explore the impact of different temporal stress conditions on the regulators associated with skeletal muscle hypertrophy in bovine myocytes. Bovine satellite cells (BSCs) were extracted from three-month-old Holstein bull calves and subjected to myogenic differentiation under three thermal treatments: 38 °C (control; CON), 39.5 °C (moderate heat stress; MHS), and 41 °C (extreme heat stress; EHS) for a duration of 3 or 48 h. Exposure to EHS resulted in elevated (P < 0.01) expression levels of heat shock protein (HSP)20, HSP27, HSP70, and HSP90, along with increased (P < 0.01) protein levels. Moreover, cells exposed to MHS and EHS exhibited enhanced (P < 0.01) gene expression of myoblast determination protein 1 (MyoD), while myogenin (MyoG) was overexpressed (P < 0.01) in cells exposed to EHS. These findings suggest that heat exposure can potentially induce myogenic differentiation through the modulation of myogenic regulatory factors. Furthermore, our investigations revealed that exposure to EHS upregulated (P < 0.01) myosin heavy chain (MHC) I expression, whereas MHC IIA (P < 0.01) and IIX (P < 0.01) expression were increased; P < 0.01) under MHS conditions. These observations suggest that the temperature of the muscle may alter the proportion of muscle fiber types. Additionally, our data indicated that EHS activated (P < 0.01) the expression of insulin-like growth factor 1 (IGF-1) and triggered the activation of the Akt/mTOR/S6KB1 pathway, a known anabolic pathway associated with cellular protein synthesis. Consequently, these altered signaling pathways contributed to enhanced protein synthesis and increased myotube size. Overall, the results obtained from our current study revealed that extreme heat exposure (41 °C) may promote skeletal muscle hypertrophy by regulating myogenic regulatory factors and IGF-1-mediated mTOR pathway in bovine myocytes.

Effects of rumen-protective γ-aminobutyric acid additive on lactation performance and serum biochemistry in heat-stressed cows

In the context of global warming, heat stress has become one of the major stress factors limiting dairy cattle production. Although many methods have been explored to help cows mitigate the negative effects of heat stress during the hot summer months, maintaining the performance of high-yielding cows under heat stress is still a great challenge. The aim of this trial was to investigate the effect of RP-GABA in the diet on milk yield, milk composition and serum biochemical parameters in heat-stressed cows. Twenty Chinese Holstein cows in early lactation (51.00 ± 4.92 kg milk/d, 71 ± 10.94 d in milk and 2.68 ± 0.73 parities) were included in this experiment and randomly divided into four groups (n = 5/group). The four experimental groups consisted of one control group (0 g RP-GABA/d) and three treatment groups, given 5, 7.5 and 10 g RP-GABA/d of dry matter (DM) per cow, respectively. The results showed that supplementing high-yielding cows with 10 g/d of RP-GABA improved milk protein production but had no effect on the improvement of other production performance, the alleviation of heat stress in cows, or the improvement of immune function and antioxidant capacity. Ultimately, we conclude that the supplementation of 10 g/d RP-GABA to heat-stressed, high-yielding dairy cows can provide a degree of performance enhancement. Furthermore, our study provides some reference for nutritional improvement measures for summer heat stress in dairy cows, especially high-yielding cows.

Heat Stress: A Serious Disruptor of the Reproductive Physiology of Dairy Cows

Global warming is a significant threat to the sustainability and profitability of the dairy sector, not only in tropical or subtropical regions but also in temperate zones where extreme summer temperatures have become a new and challenging reality. Prolonged exposure of dairy cows to high temperatures compromises animal welfare, increases morbidity, and suppresses fertility, resulting in devastating economic losses for farmers. To counteract the deleterious effects of heat stress, cattl e employ various adaptive thermoregulatory mechanisms including molecular, endocrine, physiological, and behavioral responses. These adaptations involve the immediate secretion of heat shock proteins and cortisol, followed by a complex network of disrupted secretion of metabolic and reproductive hormones such as prolactin, ghrelin, ovarian steroid, and pituitary gonadotrophins. While the strategic heat stress mitigation measures can restore milk production through modifications of the microclimate and nutritional interventions, the summer fertility records remain at low levels compared to those of the thermoneutral periods of the year. This is because sustainment of high fertility is a multifaceted process that requires appropriate energy balance, undisrupted mode of various hormones secretion to sustain the maturation and fertilizing competence of the oocyte, the normal development of the early embryo and unhampered maternal-embryo crosstalk. In this review, we summarize the major molecular and endocrine responses to elevated temperatures in dairy cows, as well as the impacts on maturing oocytes and early embryos, and discuss the consequences that heat stress brings about in dairy cattle fertility.

Invited review: From heat stress to disease-Immune response and candidate genes involved in cattle thermotolerance

Heat stress implies unfavorable effects on primary and functional traits in dairy cattle and, in consequence, on the profitability of the whole production system. The increasing number of days with extreme hot temperatures suggests that it is imperative to detect the heat stress status of animals based on adequate measures. However, confirming the heat stress status of an individual is still challenging, and, in consequence, the identification of novel heat stress biomarkers, including molecular biomarkers, remains a very relevant issue. Currently, it is known that heat stress seems to have unfavorable effects on immune system mechanisms, but this information is of limited use in the context of heat stress phenotyping. In addition, there is a lack of knowledge addressing the molecular mechanisms linking the relevant genes to the observed phenotype. In this review, we explored the potential molecular mechanisms explaining how heat stress affects the immune system and, therefore, increases the occurrence of immune-related diseases in cattle. In this regard, 2 relatively opposite hypotheses are under focus: the immunosuppressive action of cortisol, and the proinflammatory effect of heat stress. In both hypotheses, the modulation of the immune response during heat stress is highlighted. Moreover, it is possible to link candidate genes to these potential mechanisms. In this context, immune markers are very valuable indicators for the detection of heat stress in dairy cattle, broadening the portfolio of potential biomarkers for heat stress.

Heat stress promotes adaptive physiological responses and alters mrna expression of ruminal epithelium markers in Bos taurus indicus cattle fed low- or high-energy diets

This research aimed to evaluate the impact of temperature and energy status on the thermal indices, physiological parameters, and ruminal papilla mRNA expression levels of Zebu beef heifers (Bos taurus indicus). In this trial, we used six ruminal-cannulated Nellore females. The experimental design was a 6 × 6 Latin square, with six treatments and six periods. The research used a 2 × 2 + 2 factorial scheme. The arrangement comprised: two thermal conditions [thermoneutrality (TN; 21.6 °C) or heat stress (HS, 34 °C)]; two dietary energy levels (low or high-energy); and two additional treatments, with heifers exposed to the TN, but pair-fed with females exposed to HS (PFTN). For our purposes, body temperature, heart and respiratory rates were measured and the relative mRNA expression was quantified using the PCR-RT technique. Compared to TN or PFTN, the HS increased the body temperature measurements in the morning and evening (p ≤ 0.04). Heart rate was 22% greater for heifers under HS than for TN (p < 0.01) and 13% higher for those under HS than PFTN (p = 0.03) in the morning. Respiratory rates increased with HS exposure compared to TN or PFTN (p < 0.01). Heifers submitted to HS and fed low-energy diets had and tended to have lower caspase 3 (CASP3, p <i=></i> 0.001) and sodium-glucose cotransporter type 1 (SGLT1; p = 0.17) mRNA expressions, respectively. Heat-stressed heifers fed low-energy diets also increased the putative anion transporter (PAT1; p ≤ 0.01) mRNA expressions by 60%. Heifers under HS-fed high-energy diets had greater kallikrein-related peptidase (KLK) 9 expressions (p = 0.02), while KLK10 (p = 0.11) tended to be up-regulated in heifers in TN-fed a low-energy diets. In conclusion, heat stress down-regulated the mRNA expression of rumen markers related to short-chain fatty acids transport and pH modulation.

Heat Stress Effects on Physiological and Blood Parameters, and Behavior in Early Fattening Stage of Beef Steers

This study was conducted to investigate the effect of heat stress (HS) on physiological, blood, and behavioral parameters, according to the temperature-humidity index (THI), in beef steers. Twelve Korean native beef steers (342.7 ± 13.81 days old, body weight (BW) of 333.0 ± 18.53 kg) were used in this experiment. Beef steers were randomly distributed into three homogenized groups (four beef steers each) for 14 days, namely, threshold (THI = 64-71), mild-moderate (THI = 72-79), and severe (THI = 80-87). Feed and water intake were recorded daily. Physiological parameters, including heart rate and rectal temperature, and behavioral patterns (standing and lying down) were measured weekly. Blood was sampled every week to analyze hormones, heat shock protein (HSP) levels, metabolites, and hematological parameters. All data were analyzed using repeated-measures analysis. Beef steers exposed to severe THI had significantly increased (p < 0.001) water intake, heart rate, and rectal temperature compared to the threshold and mild-moderate THI beef steers. Additionally, increased blood cortisol (p < 0.001), HSP70 (p < 0.001), blood urea nitrogen (BUN) (p = 0.014), and time spent standing (p < 0.001) were observed in beef steers after exposure to severe THI compared to beef steers in the threshold and mild-moderate THI groups. However, dry matter intake, blood glucose, and non-esterified fatty acids were not different among the THI groups. In conclusion, heart rate, rectal temperature, blood cortisol, HSP70, BUN, and time spent standing were closely associated with severe HS conditions in beef steers. These phenomena indicated that beef steers exposed to HS modulated their behavior and blood parameters, as well as their physiological response, to maintain homeostasis.

Impact of Cold Stress on Physiological, Endocrinological, Immunological, Metabolic, and Behavioral Changes of Beef Cattle at Different Stages of Growth

The purpose of this study was to investigate the effect of cold stress (CS) on the physiological, blood, and behavioral parameters of beef cattle according to their growth stage. Twelve calves in the growing stages (220.4 ± 12.33 kg, male and non-castrated) and twelve steers in the early fattening stages (314.2 ± 18.44 kg) were used in this experiment. The animals were randomly distributed into three homogenized groups (four animals each) for 14 days, namely threshold, mild–moderate cold stress (MCS), and extreme cold stress (ECS), according to the outside ambient temperature. The feed and water intakes were recorded daily. The physiological parameters, blood parameters, and behavioral patterns were measured weekly. All data were analyzed using repeated-measures analysis. The calves exposed to the ECS decreased (p < 0.064, tendency) their dry matter intake compared to the threshold and MCS groups. The HR and RT increased (p < 0.001) in the ECS compared to the threshold in calves and steers. Moreover, increased (p < 0.05) blood cortisol, non-esterified fatty acids (NEFA), and time spent standing were observed after exposure to ECS in calves and steers. However, the calves exposed to the ECS had decreased (p = 0.018) blood glucose levels compared to the threshold. In conclusion, ECS affects the dry matter intake, HR, RT, blood cortisol, NEFA, and behavioral patterns in beef calves and steers. This phenomenon indicated that beef cattle exposed to CS modulated their behavior and blood parameters as well as their physiological response to maintain homeostasis regardless of the growth stage.

Expression profiling of heat shock protein genes in whole blood of Romosinuano cattle breed

Background and Aim: Heat shock proteins are highly conserved proteins that work as molecular chaperones expressed in response to thermal stress. This study aimed to determine the expression profile of genes related to the heat stress response in whole blood obtained from the Romosinuano creole breed. Materials and Methods: Real-time polymerase chain reaction was performed to analyze the transcript of hsp90, hsp70, hsp60, and hsf1 in the whole blood of Romosinuano under different temperature-humidity indices (THIs). Results: The expression levels of the hsp70 and hsf1 genes at the high-THI level were higher (p = 0.0011 and p = 0.0003, respectively) than those at the low-THI level. In addition, no differences in the expression levels of the hsp60 and hsP90 genes were detected between the two THIs. Conclusion: The overexpression of hsf1 and hsp70 genes play an important role in protecting cells from damage induced by heat stress. Keywords: climate change, external environment, heat shock proteins, heat stress, mRNA, temperature-humidity index.

Expression profiling of heat shock protein genes in whole blood of Romosinuano cattle breed

Background and Aim

Heat shock proteins are highly conserved proteins that work as molecular chaperones expressed in response to thermal stress. This study aimed to determine the expression profile of genes related to the heat stress response in whole blood obtained from the Romosinuano creole breed.

Materials and Methods

Real-time polymerase chain reaction was performed to analyze the transcript of hsp90, hsp70, hsp60, and hsf1 in the whole blood of Romosinuano under different temperature-humidity indices (THIs).

Results

The expression levels of the hsp70 and hsf1 genes at the high-THI level were higher (p = 0.0011 and p = 0.0003, respectively) than those at the low-THI level. In addition, no differences in the expression levels of the hsp60 and hsP90 genes were detected between the two THIs.

Conclusion

The overexpression of hsf1 and hsp70 genes play an important role in protecting cells from damage induced by heat stress.

Temperature Fluctuations Modulate Molecular Mechanisms in Skeletal Muscle and Influence Growth Potential in Beef Steers

Our investigation elucidated the effects of severe temperature fluctuations on cellular and physiological responses in beef cattle. Eighteen Red Angus beef steers with an average body weight of 351 ± 24.5 kg were divided into three treatment groups: 1) Control (CON), exposed to a temperature-humidity index (THI) of 42 for 6 h without any temperature changes; 2) Transport (TP), subjected to a one-mile trailer trip with a THI of 42 for 6 h; and 3) Temperature swing (TS), exposed to a one-mile trailer trip with a THI shift from 42 to 72-75 for 3 h. Our findings indicate that TS can induce thermal stress in cattle, regardless of whether the overall temperature level is excessively high or not. Behavioral indications of extreme heat stress in the cattle were observed, including extended tongue protrusion, reduced appetite, excessive salivation, and increased respiratory rate. Furthermore, we observed a pronounced overexpression (P < 0.05) of heat shock proteins (HSPs) 20, 27, and 90 in response to the TS treatment in the longissimus muscle (LM). Alterations in signaling pathways associated with skeletal muscle growth were noted, including the upregulation (P < 0.01) of Pax7, Myf5, and myosin heavy chain (MHC) isoforms. In addition, an increase (P < 0.05) in transcription factors associated with adipogenesis was detected (P < 0.05), such as PPARγ, C/EBPα, FAS, and SCD in the TS group, suggesting the potential for adipose tissue accumulation due to temperature fluctuations. Our data illustrated the potential impacts of these temperature fluctuations on the growth of skeletal muscle and adipose tissue in beef cattle.

Heat shock protein 27 regulates myogenic and self-renewal potential of bovine satellite cells under heat stress

While satellite cells play a key role in the hypertrophy, repair, and regeneration of skeletal muscles, their response to heat exposure remains poorly understood, particularly in beef cattle. This study aimed to investigate the changes in the transcriptome, proteome, and proliferation capability of bovine satellite cells in response to different levels of heat stress (HS) and exposure times. Satellite cells were isolated from 3-mo-old Holstein bulls (body weight: 77.10 ± 2.02 kg) and subjected to incubation under various temperature conditions: 1) control (38 °C; CON), 2) moderate (39.5 °C; MHS), and extreme (41 °C; EHS) for different durations ranging from 0 to 48 h. Following 3 h of exposure to extreme heat (EHS), satellite cells exhibited significantly increased gene expression and protein abundance of heat shock proteins (HSPs; HSP70, HSP90, HSP20) and paired box gene 7 (Pax7; P < 0.05). HSP27 expression peaked at 3 h of EHS and remained elevated until 24 h of exposure (P < 0.05). In contrast, the expression of myogenic factor 5 (Myf5) and paired box gene 3 (Pax3) was decreased by EHS compared to the control at 3 h of exposure (P < 0.05). Notably, the introduction of HSP27 small interference RNA (siRNA) transfection restored Myf5 expression to control levels, suggesting an association between HSP27 and Myf5 in regulating the self-renewal properties of satellite cells upon heat exposure. Immunoprecipitation experiments further confirmed the direct binding of HSP27 to Myf5, supporting its role as a molecular chaperone for Myf5. Protein-protein docking algorithms predicted a high probability of HSP27-Myf5 interaction as well. These findings indicate that extreme heat exposure intrinsically promotes the accumulation of HSPs and modulates the early myogenic regulatory factors in satellite cells. Moreover, HSP27 acts as a molecular chaperone by binding to Myf5, thereby regulating the division or differentiation of satellite cells in response to HS. The results of this study provide a better understanding of muscle physiology in heat-stressed cells, while unraveling the intricate molecular mechanisms that underlie the HS response in satellite cells.

The profile of HSPA1A gene expression and its association with heat tolerance in crossbred cattle and the tropically adapted dwarf Vechur and Kasaragod

Certain livestock breeds are adapted to hot and humid environments, and these breeds have genetics that could be useful in a changing climate. The expression of several genes has been identified as a useful biomarker for heat stress. In this study, the responses to heat exposure of heat-tolerant Vechur and Kasaragod cattle found in Kerala state in India (also known as dwarf Bos taurus indicus) were compared to crossbred cattle (crosses of Bos t. taurus with Bos t. indicus). At various time points during heat exposure, rectal temperature and the expression of HSPA1A were determined, and the relationship between them was characterized. We characterized HSPA1A mRNA in Vechur cattle and performed molecular clock analysis. The expression of HSPA1A between the lineages and at different temperature humidity index (THI) was significant. There were significant differences between the expression profiles of HSPA1A in Kasaragod and crossbred (p < 0.01) and Vechur and crossbred (p < 0.01) cattle, but no significant difference in expression was observed between Vechur and Kasaragod cattle. The genetic distance between Vechur, B. grunniens, B. t. taurus, and B. t. indicus was 0.0233, 0.0059, and 0.007, respectively. The genetic distance between Vechur and the Indian dwarf breed Malnad Gidda was 0.0081. A molecular clock analysis revealed divergent adaptive evolution of Vechur cattle to B. t. taurus, with adaptations to the high temperatures and humidity that are prevalent in their breeding tract in Kerala, India. These results could also prove useful in selecting heat-tolerant animals using HSPA1A as a marker.

Influence of dietary fiber intake and soluble to insoluble fiber ratio on reproductive performance of sows during late gestation under hot climatic conditions

This study evaluated dietary fiber (DF) level and the ratio of soluble fiber (SF): insoluble fiber (ISF) impact on sows' reproductive performance under heat stress. Forty sows at day 90 of gestation were assigned to four treatments. HH diet had, 20% DF, 1:4, SF:ISF ratio; HL, 20% DF, 1:6, SF:ISF ratio; LH, 14% DF, 1:4, SF:ISF, LL, 14% DF, 1:6, SF:ISF. Results showed that; lactation back-fat loss was lower (P < 0.05) in HH . Feed intake was higher (P < 0.05) in HH and HL. Farrowing duration shorter (P < 0.05) in HH. Constipation index was higher (P < 0.05) in HH and LH. Weaning piglets' body weight was greater (P < 0.05) in HH than LH and LL. Hair cortisol was lower (P < 0.05) in HH than HL, and LL. Acetate, propionate, isovalerate, and butyrate was higher (P < 0.05) in HH and LH. Plasma zonulin, fecal lipocalin-2 were lower (P < 0.05) in HH, and HL. Superoxide dismutase tended to be higher (P = 0.056) and malondialdehyde tended to be lower (P = 0.069) in HH and HL. We opined that higher levels of dietary fiber and soluble fiber could ameliorate heat stress in gestating sows.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

Dietary supplementation with L-glutamine enhances immunity and reduces heat stress in Hanwoo steers under heat stress conditions

This study investigated the effects of L-glutamine (Gln) supplementation on growth performance, physiological traits, heat shock proteins (HSPs), and gene expression related to muscle and adipose tissue development in Hanwoo steers under heat stress (HS) conditions. Eight Hanwoo steers (initial body weight [BW] 570.7 ± 43.6 kg, months of age 22.3 ± 0.88) were randomly separated into two groups, control and treatment, and supplied with the concentration (1.5% of BW kg/day/head) and rice straw (1.5 kg/day/head). The treatment group were fed the Gln supplementation (0.5% of concentration, as-fed basis) once a day at 08:00 h. Blood samples for the assessment of haematological and biochemical parameters and the separation of peripheral blood mononuclear cells (PBMCs) were collected four times, at 0, 3, 6, and 10 weeks of the experiment. Feed intake was measured daily. BW to analyze growth performance and hair follicle collection to analyze the expression of HSPs were executed four times at 0, 3, 6, and 10 weeks. To analyze gene expression, longissimus dorsi muscle samples were collected by biopsy at the end of the study. As a result, growing performance, including final BW, average daily gain, and gain-to-feed ratio, were not different between the two groups. Leukocytes including lymphocytes and granulocytes, tended to increase in the Gln supplementation group (p = 0.058). There were also no differences in biochemical parameters shown between the two groups, except total protein and albumin, both of which were lower in the Gln supplementation group (p < 0.05). Gene expressions related to muscle and adipose tissue development were not different between the two groups. As temperature-humidity index (THI) increased, HSP70 and HSP90 expression in the hair follicle showed a high correlation. HSP90 in the hair follicle was decreased in the treatment group compared with the control group at 10 weeks (p < 0.05). Collectively, dietary Gln supplementation (0.5% of concentration, as-fed basis) may not be influential enough to affect growth performance and gene expression related to muscle and adipose tissue development in steers. However, Gln supplementation increased the number of immune cells and decreased HSP90 in the hair follicle implying HS reduction in the corresponding group.

Quantifying heat stress; the roles on metabolic status and intestinal integrity in poultry, a review

Heat stress adversely affects intestinal barrier integrity ranging from minor enterocyte injury to fatal inflammatory heat shocks. The current review discusses the physiological mechanisms of the adaptive response of poultry and the nutritional interventions to improve intestinal integrity during heat stress. There are several possible metabolic mechanisms of protection including stress adaptation signaling pathways, blood flow, intestinal barrier permeability, epithelial cell proliferation, antioxidant status, microbiota composition, expression of heat shock proteins, inflammatory responses, and energy metabolism. The current review discusses the methods of intestinal permeability determination in order to estimate the extent of damage in the farm. There is a lack of knowledge about the nutritional strategies and the interaction between nutrients to reduce intestinal barrier damage and elucidate mechanisms in heat stress.

Basal Reactivity Evaluated by Infrared Thermography in the "Caballo de Deporte Español" Horse Breed According to Its Coat Color

Horses have been valued for their diversity of coat color since prehistoric times. In particular, the pleiotropic effect that coat color genes have on behavior determines the way the horse perceives and reacts to its environment. The primary aim of this study was to evaluate the influence of coat color on basal reactivity assessed with infrared thermography as eye temperature at rest (ETR), determine their relation with the results obtained by these horses in Show Jumping competitions and to estimate the genetic parameters for this variable to test its suitability for genetic selection. A General Linear Model (GLM) and Duncan post-hoc analysis indicated differences in ETR due to coat color, sex, age, location, and breed-group factors. A Spearman’s rank correlation of 0.11 (p < 0.05) was found with ranking, indicating that less reactive horses were more likely to achieve better rankings. Heritability values ranged from 0.17 to 0.22 and were computed with a model with genetic groups and a model with residual variance heterogeneity. Breeding values were higher with the last genetic model, thus demonstrating the pleiotropic effect of coat color. These results indicate that ETR has a suitable genetic basis to be used in the breeding program to select for basal reactivity due to coat color.

Exposure to high thermal conditions for a long time induces apoptosis and decreases total RNA concentration in peripheral blood mononuclear cells among Indian Zebu–Jersey crossbreds

Background and Aim:

Global warming has grave consequences on livestock production systems and profound negative effects on animal production. This study aimed to carry out an in vitro thermal stress stimulation (TSS) of bovine peripheral blood mononuclear cells (PBMCs) using different thermal assault conditions (TACs), including normal to extreme temperatures and varying durations of thermal exposure (DTE) to understand how PBMCs of Indian Zebu–Jersey crossbreds respond to various levels and durations of heat shock.

Materials and Methods:

Ten milliliters of blood were collected from 70 Indian Zebu–Jersey crossbreds under aseptic conditions and were sampled for isolating PBMCs. Peripheral blood mononuclear cells were divided into seven groups, each comprising 10 PBMC samples isolated from 10 different animals. Aliquots of 500 μL of PBMCs were stressed by exposure to different TACs (37, 40, and 45°C) for DTEs of 3 or 6 h. Subsequently, the cells were harvested. The control unstressed samples (500 μL aliquots of PBMCs) were exposed to no TAC (0°C) and zero DTE (0 h). Total RNA from all the treatment groups of PBMCs were isolated and quantitated.

Results:

We found a very strong association between TACs and RNA levels. In addition, PBMCs viability was negatively affected by heat shock. This led to an exponential reduction in PBMC count as TACs toughened. Only 3.59 × 10⁵ ± 0.34 cells/mL were viable after exposure to 45°C for a 6 h DTE. This cell viability was lower than that measured in controls subjected to no stress and zero time DTE (2.56 × 10⁷ ± 0.22 cells/mL). We also observed a reduction in the concentration of RNA isolated from thermally stressed PBMCs.

Conclusion:

In vitro TSS of PBMCs provided biological information on the response of cellular systems to heat shock after exposure to TACs. This will help to mitigate and manage the effects of thermal stress in bovine species. The association between the reduction in PBMC count after in vitro TSS and the expression of heat shock protein 70 gene will be investigated in the future to further understand how Indian Zebu–Jersey crossbreds respond to in vitro thermal conditions. This will be used to determine the in vivo response of Indian Jersey crossbreds to different environmental thermal conditions and will further enable the in vivo understanding of thermotolerance potentials of bovine species for better adaptation, survival, and production performance.

Identification of Potential Biomarkers and Metabolic Pathways of Different Levels of Heat Stress in Beef Calves

Heat stress (HS) damages the global beef industry by reducing growth performance causing high economic losses each year. However, understanding the physiological mechanisms of HS in Hanwoo calves remains elusive. The objective of this study was to identify the potential biomarkers and metabolic pathways involving different levels of heat stress in Hanwoo calves. Data were collected from sixteen Hanwoo bull calves (169.6 ± 4.6 days old, BW of 136.9 ± 6.2 kg), which were maintained at four designated ranges of HS according to the temperature−humidity index (THI) including: threshold (22 to 24 °C, 60%; THI = 70 to 73), mild (26 to 28 °C, 60%; THI = 74 to 76), moderate (29 to 31 °C, 80%; THI = 81 to 83), and severe (32 to 34 °C, 80%; THI = 89 to 91) using climate-controlled chambers. Blood was collected once every three days to analyze metabolomics. Metabolic changes in the serum of calves were measured using GC-TOF-MS, and the obtained data were calculated by multivariate statistical analysis. Five metabolic parameters were upregulated and seven metabolic parameters were downregulated in the high THI level compared with the threshold (p < 0.05). Among the parameters, carbohydrates (ribose, myo-inositol, galactose, and lactose), organic compounds (acetic acid, urea, and butenedioic acid), fatty acid (oleic acid), and amino acids (asparagine and lysine) were remarkably influenced by HS. These novel findings support further in-depth research to elucidate the blood-based changes in metabolic pathways in heat-stressed Hanwoo beef calves at different levels of THI. In conclusion, these results indicate that metabolic parameters may act as biomarkers to explain the HS effects in Hanwoo calves.

Characterization of thermo-physiological, hematological, and molecular changes in response to seasonal variations in two tropically adapted native cattle breeds of Bos indicus lineage in hot arid ambience of Thar Desert

The selection of climate resilient animal is necessary to secure the future of sustainable animal production. The present investigation therefore was an effort to unravel answers to the adaptation at physiological, hematological, and molecular levels in cows of hot arid region that helps them to survive harsh environment, to continue production and reproduction. This investigation was carried out in indicine cows over a period of one year, encompassing four seasons, wherein physiological data of 50 animals, hematological data of 15 animals, and gene expression profile of 5 animals from each of Sahiwal and Kankrej breeds per season was generated. In total, 5600 physiological observations, 1344 hematological observations, and 480 molecular samples were processed. The meteorological data revealed a high diurnal variation of temperature across seasons, with THI exceeding 80 during the months of summer and hot-humid seasons, indicating significant heat stress (HS). The physiological parameters showed an increasing trend with the incremental THI, with significantly (p < 0.05) higher values of rectal temperature (RT), respiration rate (RR), pulse rate (PR), and body surface temperature (BST) at ventral (VT), lateral (LT), dorsal (DT), and frontal (FT), in both breeds recorded during HS. The hematological pictures also revealed significant (p < 0.05) seasonal perturbations in erythrocytic and leucocytic parameters. Moreover, the molecular response was driven by a significant (p < 0.05) upregulation of all the key HSPs, HSP70, HSP90, HSP60, and HSP40, except HSP27 during the hotter months of summer and hot-humid seasons. The expression of HSF1, an important transcriptional regulator of  HSP70 was also significantly (p < 0.05) upregulated during summer season in both breeds. All the molecular chaperones revealed a significant upregulation during the summer season, followed by a decreasing trend by hot-humid season. The study indicated a well-developed thermotolerance mechanism in animals of both breeds, with Kankrej cows exhibiting better thermotolerance compared to Sahiwal cows.

Effect of acute heat shock on stress gene expression and DNA methylation in zebu (Bos indicus) and crossbred (Bos indicus × Bos taurus) dairy cattle

Environmental temperature is one of the major factors to affect health and productivity of dairy cattle. Gene expression networks within the cells and tissues coordinate stress response, metabolism, and milk production in dairy cattle. Epigenetic DNA methylations were found to mediate the effect of environment by regulating gene expression patterns. In the present study, we compared three Indian native zebu cattle, Bos indicus (Sahiwal, Tharparkar, and Hariana) and one crossbred Bos indicus × Bos taurus (Vrindavani) for stress gene expression and differences in the DNA methylation patterns. The results indicated acute heat shock to cultured PBMC affected their proliferation, stress gene expression, and DNA methylation. Interestingly, expressions of HSP70, HSP90, and STIP1 were found more pronounced in zebu cattle than the crossbred cattle. However, no significant changes were observed in global DNA methylation due to acute heat shock, even though variations were observed in the expression patterns of DNA methyltransferases (DNMT1, DNMT3a) and demethylases (TET1, TET2, and TET3) genes. The treatment 5-AzaC (5-azacitidine) that inhibit DNA methylation in proliferating PBMC caused significant increase in heat shock-induced HSP70 and STIP1 expression indicating that hypomethylation facilitated stress gene expression. Further targeted analysis DNA methylation in the promoter regions revealed no significant differences for HSP70, HSP90, and STIP1. However, there was a significant hypomethylation for BDNF in both zebu and crossbred cattle. Similarly, NR3C1 promoter region showed hypomethylation alone in crossbred cattle. Overall, the results indicated that tropically adapted zebu cattle had comparatively higher expression of stress genes than the crossbred cattle. Furthermore, DNA methylation may play a role in regulating expression of certain genes involved in stress response pathways.

Effects of different protein levels on growth performance and stress parameters in beef calves under heat stress

This study investigated the effects of dietary protein levels under various heat stress (HS) conditions on the growth performance and stress parameters in Korean native beef calves. Male calves (n = 40; initial BW = 202.2 ± 3.31 kg) were randomly assigned to climatic-controlled chambers with 3 × 3 factorial arrangements. Calves were assigned into three dietary protein levels (low protein; LP = 12.5%, medium protein; MP = 15%, and high protein; HP = 17.5%) and three HS levels [mild: temperature-humidity index (THI) = 74 to 76, moderate: THI = 81 to 83, and severe: THI = 89 to 91] with control (threshold: THI = 70 to 73 and dietary protein level 12.5%). The calves were subjected to ambient temperature (22 °C) for 7 days and subsequently to the temperature and humidity corresponding to the target THI level for 21 days. The data were analyzed using the repeated-measures analysis by the GLM procedure of SAS. As a result, average daily gain (ADG) was decreased (P < 0.05) under severe HS level compared to the mild and moderate HS stress levels. However, HP increased ADG (P < 0.05) than moderate levels (LP) and severe levels (LP and MP). Under different HS levels (mild, moderate, and severe), HR, RT, and blood cortisol were increased (P < 0.05) compared to a threshold level, but no differences were observed in the parameters among various protein levels. Varied HS levels decreased the levels of blood glucose, NEFA, and amino acids (AAs) (lysine and glutamic acid) compared to a threshold (P < 0.05). But, the HP group resulted in increased (P < 0.05) levels of blood glucose, NEFA, and AAs (lysine and glutamic acid) compared to LP and MP groups under severe HS stress. The expression level of the HSP70 gene in peripheral blood mononuclear cell (PBMC) and hair follicles was increased (P < 0.05) following an increase in moderate and severe HS levels. Also, HSP70 gene expression in the HP group was decreased (P < 0.05) compared with LP and MP groups under intense HS level. Overall, HS in Korean native beef calves exhibited negative effects on ADG, blood glucose, NEFA, and AA profile. However, 17.5% of dietary protein (HP) could compensate for the growth of heat-exposed Korean native beef calves through the regulation of homeostasis by protein and energy metabolism. Also, it was evident that adequate protein (HP) is used as a major nutrient for HSP70 synthesis in PBMC and hair follicles causing, a boost in the immune system of heat-exposed Korean native beef calves.

Metabolic Responses of Dietary Fiber during Heat Stress: Effects on Reproductive Performance and Stress Level of Gestating Sows

Heat stress is an important issue, and the addition of fiber to the diet is an option in modifying intestinal health. This study evaluated the effect of acid detergent fiber (ADF) levels on reproductive performance, intestinal integrity, and metabolism of gestating sows, and its carry-over effect on the lactation period during heat stress. The diets included 4.3% (Low fiber; LF), 5.4% (Medium fiber; MF), and 6.5% (High fiber; HF) ADF. Sows fed the HF diet showed a lower respiratory rate, hair cortisol concentration, and farrowing duration compared with the LF treatment. The HF diet increased the pyruvate, citrate cycle, glyoxylate, dicarboxylate, and thiamine metabolism compared with the MF. The concentration of acetate and total short-chain fatty acids were increased in the sows fed the HF diet. The gene expression of glucose transporter 3 and glucose transporter 4 was increased in the HF treatment. The gene expression of heat shock protein 70 was decreased in the HF treatment. The HF diet during gestation increased feed intake, constipation index, piglet weight, and litter weight compared with the LF. Sows in the LF treatment showed the greatest digestibility of crude protein and the lowest digestibility of ADF. In conclusion, a 6.5% ADF level is recommended for gestating sows during heat stress.

L-theanine mediates the p38MAPK signaling pathway to alleviate heat-induced oxidative stress and inflammation in mice

L-theanine, an active ingredient in the tea plant (Camellia sinensis) associated with calming, is widely used as a functional ingredient and dietary supplement. In this study, a heat stress mouse...

The Correlation between Extracellular Heat Shock Protein 70 and Lipid Metabolism in a Ruminant Model

Metabolic stress in early lactation cows is characterized by lipolysis, ketogenesis, insulin resistance and inflammation because of negative energy balance and increased use of lipids for energy needs. In this study the relationship between lipid metabolite, lipid-based insulin resistance, and hepatocyte functionality indexes and tumor necrosis factor alpha (TNF-α) with extracellular heat shock protein 70 (eHsp70) was investigated. The experiment included 50 cows and all parameters were measured in blood serum. In cows with a more pronounced negative energy balance, the following was determined: a higher concentration of eHsp70, TNF-α, non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHB), NEFA to insulin and NEFA to cholesterol ratio and lower concentration of cholesterol, very low-density lipoproteins (VLDL), low density lipoproteins (LDL) and liver functionality index (LFI). The eHsp70 correlated negatively with the values of cholesterol, VLDL, LDL, and triglycerides, while correlated positively with the level of NEFA and BHB. A higher concentration of eHsp70 suggests the development of fatty liver (due to a higher NEFA to cholesterol ratio and lower LFI) and insulin resistance (due to a lower revised quantitative insulin sensitivity check index RQUICKI-BHB and higher NEFA to insulin ratio). The eHsp70 correlated positively with TNF-α. Both TNF-α and eHsp70 correlated similarly to lipid metabolites. In cows with high eHsp70 and TNF-α values we found higher concentrations of NEFA, BHB, NEFA to insulin and NEFA to cholesterol ratio and a lower concentration of triglycerides and VLDL cholesterol compared to cows that had only high TNF-α values. Based on the positive correlation between eHsp70 and TNF-α, their similar relations, and the additional effect of eHsp70 (high TNF-α + eHsp70 values) on lipid metabolites we conclude that eHsp70 has pro-inflammatory effects implicating lipolysis, fatty liver, and fat tissue insulin resistance.

Chemerin Regulates Epithelial Barrier Function of Mammary Glands in Dairy Cows

Epithelial barrier function in the mammary gland acts as a forefront of the defense mechanism against mastitis, which is widespread and a major disorder in dairy production. Chemerin is a chemoattractant protein with potent antimicrobial ability, but its role in the mammary gland remains unelucidated. The aim of this study was to determine the function of chemerin in mammary epithelial tissue of dairy cows in lactation or dry-off periods. Mammary epithelial cells produced chemerin protein, and secreted chemerin was detected in milk samples. Chemerin treatment promoted the proliferation of cultured bovine mammary epithelial cells and protected the integrity of the epithelial cell layer from hydrogen peroxide (H₂O₂)-induced damage. Meanwhile, chemerin levels were higher in mammary tissue with mastitis. Tumor necrosis factor alpha (TNF-α) strongly upregulated the expression of the chemerin-coding gene (RARRES2) in mammary epithelial cells. Therefore, chemerin was suggested to support mammary epithelial cell growth and epithelial barrier function and to be regulated by inflammatory stimuli. Our results may indicate chemerin as a novel therapeutic target for diseases in the bovine mammary gland.

Responses of beef calves to long-term heat stress exposure by evaluating growth performance, physiological, blood and behavioral parameters

The objective of this study was to explore the responses of beef calves to long-term heat stress (HS) exposure at various levels in comparison with the animals under thermoneutral conditions by evaluating growth performance, physiological, blood, and behavioural parameters. Data were collected from sixteen beef calves (BW: 136.9 ± 6.23 kg; age: 169.6 ± 4.60 d) kept at four stress levels of designated temperature humidity index (THI): threshold (22-24 °C, 60%; THI = 70 to 73), mild (26-28 °C, 60%; THI = 74 to 76), moderate (29-31 °C, 80%; THI = 81 to 83), and severe (32-34 °C, 80%; THI = 89 to 91) stress levels in climatic controlled chambers. Feed and water intake were recorded daily, and body weight was measured once a week. Blood was sampled every three days to analyse metabolite parameters. Dry matter intake (DMI) (p = 0.069, tendency) and blood glucose levels (p = 0.028) were decreased after sudden exposure to HS conditions (severe THI levels). Also, blood cortisol (p = 0.002), glutamic-oxaloacetic transaminase (GOT) (p = 0.009), blood urea nitrogen (BUN) (p = 0.004) and standing time (p = 0.009) were increased in moderate and severe THI levels compared with threshold after exposure to HS conditions. However, in the severe THI group, blood cortisol (p < 0.05), glucose (p < 0.05), GOT (p < 0.05) and BUN (p < 0.05) levels were returned to normal range after 6-13 days of continuous HS exposure. In conclusion, DMI, blood cortisol, GOT, glucose, BUN, and standing time were closely associated with long-term HS condition in beef calves. In addition, calves exposed to HS modulated their physiological responses that resulted in the regulation of the pertinent blood metabolites in the blood to maintain homeostasis during the long-term HS.

Behavioural, physiological, neuro-endocrine and molecular responses of cattle against heat stress: an updated review

The negative impact of heat stress on cattle growth, development, reproduction and production has been quite alarming across the world. Climate change elevates earth surface temperature which exacerbates the wrath of heat stress on cattle. Moreover, cattle in tropical and sub-tropical countries are most commonly affected by the menace of heat stress which severely wane their production and productivity. In general, cattle exhibit various thermoregulatory responses such as behavioural, physiological, neuro-endocrine and molecular responses to counteract the terrible effects of heat stress. Amongst the aforementioned thermoregulatory responses, behavioural, physiological and neuro-endocrine responses are regarded as most conventional and expeditious responses shown by cattle against heat stress. Furthermore, molecular responses serve as the major adaptive response to attenuate the harmful effects of heat stress. Therefore, present review highlights the significance of behavioural, physiological, neuro-endocrine and molecular responses which act synergistically to combat the deleterious effects of heat stress thereby confer thermo-tolerance in cattle.

Effect of in-vitro heat stress challenge on the function of blood mononuclear cells from dairy cattle ranked as high, average and low immune responders

Background

The warming climate is causing livestock to experience heat stress at an increasing frequency. Holstein cows are particularly susceptible to heat stress because of their high metabolic rate. Heat stress negatively affects immune function, particularly with respect to the cell-mediated immune response, which leads to increased susceptibility to disease. Cattle identified as having enhanced immune response have lower incidence of disease. Therefore, the objective of this study was to evaluate the impact of in vitro heat challenge on blood mononuclear cells from dairy cattle, that had previously been ranked for immune response, in terms of heat shock protein 70 concentration, nitric oxide production, and cell proliferation.

Results

Blood mononuclear cells from dairy cattle classified as high immune responders, based on their estimated breeding values for antibody and cell-mediated responses, produced a significantly greater concentration of heat shock protein 70 under most heat stress treatments compared to average and low responders, and greater cell-proliferation across all treatments. Similarly, a trend was observed where high responders displayed greater nitric oxide production compared to average and low responders across heat treatments.

Conclusion

Overall, these results suggest that blood mononuclear cells from high immune responder dairy cows are more thermotolerant compared to average and low immune responders.

Identification of key Genes and Pathways Associated With Thermal Stress in Peripheral Blood Mononuclear Cells of Holstein Dairy Cattle

The objectives of the present study were to identify key genes and biological pathways associated with thermal stress in Chinese Holstein dairy cattle. Hence, we constructed a cell-model, applied various molecular biology experimental techniques and bioinformatics analysis. A total of 55 candidate genes were screened from published literature and the IPA database to examine its regulation under cold (25°C) or heat (42°C) stress in PBMCs. We identified 29 (3 up-regulated and 26 down-regulated) and 41 (15 up-regulated and 26 down-regulated) significantly differentially expressed genes (DEGs) (fold change ≥ 1.2-fold and P < 0.05) after cold and heat stress treatments, respectively. Furthermore, bioinformatics analyses confirmed that major biological processes and pathways associated with thermal stress include protein folding and refolding, protein phosphorylation, transcription factor binding, immune effector process, negative regulation of cell proliferation, autophagy, apoptosis, protein processing in endoplasmic reticulum, estrogen signaling pathway, pathways related to cancer, PI3K- Akt signaling pathway, and MAPK signaling pathway. Based on validation at the cellular and individual levels, the mRNA expression of the HIF1A gene showed upregulation during cold stress and the EIF2A, HSPA1A, HSP90AA1, and HSF1 genes showed downregulation after heat exposure. The RT-qPCR and western blot results revealed that the HIF1A after cold stress and the EIF2A, HSPA1A, HSP90AA1, and HSF1 after heat stress had consistent trend changes at the cellular transcription and translation levels, suggesting as key genes associated with thermal stress response in Holstein dairy cattle. The cellular model established in this study with PBMCs provides a suitable platform to improve our understanding of thermal stress in dairy cattle. Moreover, this study provides an opportunity to develop simultaneously both high-yielding and thermotolerant Chinese Holstein cattle through marker-assisted selection.

Dietary supplementation of acetate-conjugated tryptophan alters feed intake, milk yield and composition, blood profile, physiological variables, and heat shock protein gene expression in heat-stressed dairy cows

The purpose of this study was to investigate the effects of dietary supplementation of rumen-protected tryptophan (RPT) at four levels on milk yield, milk composition, blood profile, physiological variables, and heat shock protein gene expression in dairy cows under conditions of moderate-severe heat stress (MSHS, THI = 80~89). Sixteen early-lactating dairy cows (body weight = 719 ± 66.4 kg, days in milk = 74.3 ± 7.1, milk yield = 33.55 ± 3.74 kg, means ± SEM) were randomly assigned in a factorial arrangement to one of the four treatments: control group (n = 4, no RPT supplementation), 15 g/d RPT (n = 4), 30 g/d RPT (n = 4), or 60 g/d RPT group per cow (n = 4) supplemented to the TMR. A higher dry matter intake (DMI) and milk yield were found in the 30 g RPT group compared with the other groups, and the 3.5% fat-corrected milk yield, energy-corrected milk yield, milk fat, protein, β-casein, mono-unsaturated fatty acid, and poly-unsaturated fatty acid contents, and serum glucose content were observed in the 30 g RPT group (p < 0.05). The milk lactose concentration was significantly higher in the 30 g RPT group compared with the control and 60 g RPT groups (p < 0.05). The plasma cortisol level was lower, while the serotonin and melatonin concentrations were higher in the 30 g group compared with the other groups (p < 0.05). Heat shock protein (HSP) 70 expression was downregulated in the control and 15 g RPT groups, whereas the expression of HSP90 and HSPB1 remained unchanged among the groups. In particular, the 30 g RPT group was considered to have an improved DMI, milk yield, and lactose concentration, as well as anti-heat stress effects due to the simulation of serotonin and melatonin during MSHS.

Genetic Parameters of Effort and Recovery in Sport Horses Assessed with Infrared Thermography

Simple Summary

The way a horse activates (effort phase-EP) and recovers (recovery phase-RP) during a sport event can affect its sport performance. The aim of this manuscript was to test horses’ adaptation to sport performance and its genetic basis, using eye temperature assessed with infrared thermography. EP and RP were measured in 495 Spanish Sport Horses, during a performance test, considering sex (2) and genetic lines (5) as fixed effects. The ranking position obtained on the official sport competition celebrated the day after the performance test was also collected. Differences in variables due to genetic line and sex effects were found, showing that, regardless of the genetic line, stallions tended to recover better than mares after the sport test developed. High positive correlations were found between EP and RP for both fixed effects, so that, the higher the EP, the higher the RP. However, for the ranking position, a low negative correlation was found, so that the higher the eye temperature increase, the better the position. Heritabilities showed medium–high values with a medium positive genetic correlation between them. Thus, breed origins and sex influence horses’ effort and recovery during sport performance, showing a genetic basis adequate for selection.

Abstract

The way a horse activates (effort phase-EP) and recovers (recovery phase-RP) during a sport event can affect its sport performance. The aim of this manuscript was to test horses’ adaptation to sport performance and its genetic basis, using eye temperature assessed with infrared thermography. EP and RP were measured in 495 Spanish Sport Horses, during a performance test, considering sex (2) and genetic lines (5) as fixed effects. The ranking position obtained on an official sport competition was also collected. Differences in variables due to genetic line and sex effects were found, showing that, regardless of the genetic line, stallions tended to recover better than mares after the sport test developed. High positive intra-class correlations (p < 0.001) were found between EP and RP for both fixed effects, so that the higher the EP, the higher the RP. However, for the ranking position, a low negative correlation (p < 0.01) was found, so that the higher the eye temperature increase, the better the position. Heritabilities showed medium–high values with a medium positive genetic correlation between them. Thus, breed origins and sex influence horses’ effort and recovery during sport performance, showing a genetic basis adequate for selection.

Significance of molecular chaperones and micro RNAs in acquisition of thermo-tolerance in dairy cattle

Ambient temperature is considered as the major abiotic factor which regulates body physiological mechanisms of all living creatures across the globe. Variation in ambient temperature which emulates thermoneutral zone culminates in heat stress. Heat stress has been emerged as major ultimatum to livestock's growth, development, production and reproduction across the world. Livestock's responds to the heat stress via different mechanisms such as behavioral, physiological, biochemical, endocrine and molecular mechanisms. Amongst the aforementioned mechanisms, molecular mechanism plays crucial role to achieve thermo-tolerance via expression of highly conserved family of proteins known as heat shock proteins (HSPs) across livestock species. HSPs serve as molecular chaperones to ameliorate the menace of heat stress in domestic species. In addition, microRNAs are small non-coding RNA which down regulates post-transcriptional gene expression by targeting various HSPs to regulate the thermoregulatory responses in livestock species. Despite of thermal adaptation mechanisms, heat stress breaches animal body homeostasis thereby depresses their production and productivity. Therefore, veterinary researches have been targeting to explore different repertoire of HSPs and microRNAs expression to counteract the rigors of heat stress thereby confer thermo-tolerance in livestock species. The present review highlights the significance of molecular chaperones and microRNAs in the acquisition of thermo-tolerance in dairy cattle.