Search Results (146)

Background: This study investigated how chronic heat stress affects meat quality and post-slaughter muscle acidification in slow-growing yellow-feathered broilers, focusing on the roles of ALDOB and HSP90B1 in glycometabolism. Methods: From 100 to 120 days of age, broilers were kept either under thermoneutral conditions (25 ± 1 °C, N group) or cyclic heat stress (32 ± 1 °C for 9 h/day, H group). Meat quality traits (pH, shear force, drip loss, color) were measured at 0, 24, and 48 h of refrigeration (4 °C). Free amino acid and fatty acid profiles were analyzed. DF-1 cells were exposed to 43 °C for functional assays of ALDOB and HSP90B1. Results: Chronic heat stress reduced body weight, altered flavor precursors, and induced PSE-like characteristics (lower pH, higher shear force, increased drip loss, paler color), especially in leg muscles. ALDOB and HSP90B1 were upregulated in both tissues and cells. ALDOB overexpression promoted glucose consumption, while HSP90B1 suppressed lactic acid production. Conclusions: Chronic heat stress impairs growth and flavor precursors and exacerbates post-slaughter muscle acidification (primarily driven by ATP hydrolysis, with lactic acid as a secondary contributor). ALDOB and HSP90B1 may dually regulate glycometabolism under heat stress. Full article

This experiment aimed to evaluate physiological and behavioral responses of crossbred Dehong dairy buffaloes to heat stress (HS) in comparison with those in a thermoneutral (TN) environment. Twelve crossbred dairy buffaloes at similar lactation stages were randomly allocated to two groups of six animals each. Six buffaloes were exposed to HS conditions and the other six to TN conditions in an open loose-housing barn without individual stalls. Respiration rates were manually recorded at 08:00 h, 13:00 h, and 18:00 h. Duration and frequency of behaviors (standing, lying, feeding, and drinking) were continuously monitored using digital cameras for 20 consecutive days. Compared with the TN group, HS-exposed buffaloes exhibited markedly higher respiration rates (p < 0.001) and feeding frequencies (p < 0.05), but significantly shorter feeding duration throughout the observation period (p < 0.05). No significant differences were observed in the time spent standing, lying, or drinking between the two groups (p ≥ 0.05). Under HS conditions, buffaloes preferred a vertical lying posture to reduce exposure to intense solar radiation. These results suggest that crossbred Dehong dairy buffaloes can adapt to heat stress by modulating their physiological and behavioral strategies. The observed changes in physiological indices and behavioral patterns provide fundamental data for further elucidating the heat stress adaptation mechanisms in dairy buffaloes. Full article

Milk production in dairy cattle is increasingly challenged by thermal variability. This underscores the need for reliable assessment of microclimatic conditions and their interaction with animal- and management-related factors to ensure sustainable dairy production. The aim of this study was to evaluate the effects of thermal variability and selected environmental and biological factors on key milk production traits in dairy cattle. The influence of fixed factors related to production conditions and microclimatic variability, including the Temperature–Humidity Index (THI) as an indicator of thermal variability, on daily milk yield (MY), milk fat content (MF), and milk protein content (MP) was assessed. This study used a dataset covering two observation periods of daily milk production traits in cows of different breeds (Simmental, Holstein-Friesian, Red Holstein, and Brown Swiss) reared in three regions of the Republic of Serbia (Mačva, Podunavlje, and Šumadija), enabling an assessment of thermal variability under diverse production and microclimatic conditions. The expression and variability of the investigated traits were determined using the PROC FREQ and PROC MEANS procedures, while the effects of individual factors were analysed using general linear and regression models, with results expressed as least squares means. All examined factors showed a highly significant effect on MY, MF, and MP (p < 0.0001). Milk production was highest within the THI range of 51–60, corresponding to thermoneutral conditions, whereas higher THI values (>60) reflect increasing thermal load and were associated with measurable reductions in milk yield, as confirmed by statistical analysis. These findings demonstrate that thermal variability and heat stress significantly influence milk production and composition and highlight the importance of integrating microclimatic indicators into sustainability-oriented dairy management and breeding strategies. Full article

Heat stress is a major environmental stressor in poultry production that reduces growth performance and induces oxidative stress, inflammatory responses, and lung tissue injury. This study investigated the protective effects of dietary supplementation with Ginkgo biloba extract and tea polyphenols against heat stress-induced lung injury in broilers. A total of 320 one-day-old broilers were reared under standard management conditions until 21 days of age. Subsequently, 300 birds with similar body weight were selected and randomly allocated into six groups: a thermoneutral control group, a heat stress group, a heat stress group supplemented with 300 mg/kg tea polyphenols, and three heat stress groups receiving 300 mg/kg tea polyphenols combined with 100, 300, or 600 mg/kg Ginkgo biloba extract. The analysis of the results showed that heat stress significantly reduced the average daily gain and feed intake while increasing the feed conversion ratio. It also markedly increased serum lactate dehydrogenase activity and malondialdehyde levels, while decreasing antioxidant-related indicators, indicating the occurrence of oxidative stress and inflammatory responses. Histological examination revealed lung injury characterized by alveolar wall thickening, epithelial cell shedding, and disruption of the endothelial barrier, accompanied by upregulated expression of heat shock proteins and inflammation-related signaling genes. Supplementation with tea polyphenols alone partially alleviated these changes. Notably, the combined supplementation of Ginkgo biloba extract and tea polyphenols exerted more pronounced protective effects, significantly enhancing antioxidant capacity, attenuating inflammatory responses, and maintaining pulmonary barrier integrity. Among the tested levels, the groups receiving 300 mg/kg Ginkgo biloba extract in combination with tea polyphenols showed the most evident improvements. These findings suggest that the combined use of these plant-derived extracts effectively mitigates heat stress-induced lung injury in broilers. Full article

Metal-free electrodes are essential to promote electrochemical reactions, the core of sustainable energy resources. In search of better carbon-based electrode materials, we have explored several spatial arrangements of boron (B) within proximity in the graphene lattice, as evident in recent experimental observations. Multi-boron substitution enriches sites by tuning electronic structure and strengthens binding of key intermediates of oxygen reduction, oxygen evolution, and hydrogen evolution reactions facilitating electrocatalytic performance. Our optimal B-doped site shows near thermo-neutral H adsorption ($\Delta G_{H^{*}}$∼$\pm 0.4\mathrm{eV}$), consistent with experiments. The overpotentials are highly sensitive to the dopant motifs and the spread among configurations shows that experimentally accessible multi-B doping can serve as a practical active site engineering knob to achieve optimized multi-functional performance. In parallel, we find that specific multi-B configurations selectively capture and pre-activate NO_x (NO/NO₂) under ambient conditions while retaining weak affinity for NH₃. These sites also interact with SO₂ and related hazardous species, enabling selective air filtration and targeted NO_x control within the electrocatalytic scope of this study. Full article

Improving egg production under heat stress remains a major challenge in tropical poultry breeding. This study demonstrates that clutch length and hen-day egg production are robust indicators of genetic variation in heat tolerance and directly applicable to climate-resilient breeding programs in Thai native chickens. Records from 2400 Pradu Hang Dum hens across five generations were analyzed using a reaction-norm repeatability model with the temperature–humidity index (THI) as an environmental covariate. A THI threshold of 74 was identified, beyond which heat stress altered the genetic expression of both traits. Heritability estimates declined with an increasing THI, from 0.49 to 0.32 for clutch length and from 0.37 to 0.26 for hen-day egg production, indicating reduced additive genetic control under heat stress. Genetic correlations between baseline performance and heat-stress sensitivity were moderately to strongly negative (−0.46 to −0.54), revealing antagonism between productivity under thermoneutral conditions and heat tolerance. Reaction-norm breeding values showed substantial genotype-by-environment interactions, highlighting heterogeneity in heat-stress responses among genotypes. Despite thermal challenges, positive genetic trends were observed, with an average genetic trend of 1.34 eggs per generation for clutch length and 8.8 percent per generation for hen-day egg production. These results demonstrate that genetic improvement can be sustained under heat stress and support the integration of THI-based reaction-norm evaluations to identify genotypes combining reproductive efficiency with enhanced heat tolerance for climate-resilient breeding programs. Full article

Heat stress poses a considerable challenge to the modern poultry industry by negatively impacting immune system maturation and eliciting inflammatory responses. Peroxisome proliferators-activated receptors α (PPARα), predominantly expressed in metabolically active tissues such as skeletal muscle, are essential for regulating the inflammatory process. Moreover, our recent research has found that heat stress down-regulates the transcription of PPARα in broiler chickens. To study if PPARα regulation is involved in heat-stress-induced skeletal muscle inflammatory response in broiler chickens, 180 male Arbor Acres (AA) broilers aged 22 days were randomly assigned to three experimental groups: a thermoneutral condition group at 21 °C, a heat stress group at 31 °C and a heat stress group at 31 °C supplemented with the PPARα activator fenofibrate. After 7 days of adaptive feeding, the broilers were subjected to a 14-day formal experimental phase. Results demonstrated that heat stress decreased the spleen and thymus index and increased serum and breast muscle inflammatory factor concentrations (p < 0.05). Moreover, heat-stress-induced abnormal breast muscle fiber morphology in broiler chickens. Furthermore, heat stress significantly up-regulated nuclear factor kappa-B (NF-κB) expression in boiler chickens (p < 0.05). However, activating PPARα through fenofibrate improved the growth performance (p < 0.05), enhanced immune organ indexes (p < 0.05), reduced inflammatory factor concentrations (p < 0.05), alleviated breast muscle fiber morphology damage and suppressed NF-κB expression (p < 0.05) in the breast muscle of broiler chickens. Based on our previous research, these results collectively underscore that heat stress induced inflammation and up-regulated NF-κB in the breast muscle of broiler chickens by inhibiting PPARα. Full article

Neuropeptide VF (NPVF) is a member of the RFamide family of peptides and is suggested to be involved in homeostatic regulations. However, direct evidence is sparse. Here, we generated a NPVF knockout mouse model to comprehensively investigate its role in energy and glucose homeostasis controls. We show that while male Npvf^−/− mice on chow were WT-like at both room temperature (RT 22 °C) and thermoneutrality (TN 28 °C) with regards to body weight, body composition, and the parameters involved in energy homeostasis, female Npvf^−/− mice exhibit significantly reduced water intake at RT and TN regardless of food access, significantly increased the femur bone mineral content at RT and reduced the adiposity at TN. Strikingly, sex differences are absent under high-fat diet (HFD) conditions, with Npvf deletion leading to hyperphagia and increased weight gain in both sexes. Furthermore, Npvf^−/− mice on chow at RT exhibit normal glucose tolerance and insulin action for both sexes. On a HFD or at TN, Npvf^−/− mice display improved and impaired insulin action in females and males, respectively, with female Npvf^−/− mice at TN further showing an improved glucose tolerance. Collectively, these findings establish NPVF as a key regulator of energy and glucose metabolism with sex dimorphism, and are critically dependent on environmental and nutritional factors. Full article

Early diagnosis of heat load in beef cattle remains a challenge due to the limited understanding of behaviour-based indicators. This preliminary longitudinal study aimed to validate behavioural and physiological responses previously identified as heat load indicators. Black Angus steers were exposed to high environmental temperatures expected to cause heat load in the following sequence: an initial thermoneutral period, a hot period, and a recovery period. Changes in the positioning of key body parts, feeding behaviour, body maintenance, respiratory dynamics, and eye temperature were monitored. In the hot period, cattle increased their respiration rate, panting, and infrared eye temperature. Increased stepping by their left limbs suggested involvement of the right brain hemisphere in a stress response to high environmental temperatures. Cattle also held their heads more downward, ears backward, and their tail vertical, and reduced eating, grooming, and scratching during the hot period. Cattle responses to hot conditions were persistent in the recovery period, reflecting diagnostic relevance of the head, ear, and tail movements, stepping, especially by left limbs, and infrared eye temperature as non-invasive tools to identify heat load condition in cattle. The study reinforces our understanding of the specific behavioural and physiological responses to heat load condition, especially those involving left-limb stepping, ear and tail posture, and infrared eye temperature, are reliable indicators for identifying cattle experiencing high environmental temperature. Full article

The study aimed to determine the effect of acute, one-time physical effort performed under different environmental temperature conditions on erythrocyte deformability in healthy young men. This exploratory randomized parallel-group study involved 30 men randomly assigned to an experimental group exercising at −10 °C in a climatic chamber and a control group exercising under thermoneutral outdoor conditions. Erythrocyte deformability was assessed using the elongation index (EI), reflecting erythrocyte elasticity and the ability to pass through microcirculation vessels. Participants performed an incremental 20 m shuttle run test. Venous blood samples were collected before and immediately after exercise, and erythrocyte deformability was analyzed using a Lorrca analyzer across a shear stress range of 0.30–60.00 Pa. A two-factor repeated-measures analysis of variance was applied. An increase in EI after exercise was observed in both groups, predominantly at higher shear stress values, indicating enhanced erythrocyte deformability under conditions of increased shear forces. However, the magnitude of post-exertion changes differed between groups. At lower shear stress levels (0.30 Pa and 0.58 Pa), EI tended to decrease after exercise. These findings indicate that a single bout of physical effort influences erythrocyte deformability, while the potential effects of cold exposure on this response remain uncertain and warrant further investigation. Full article

Medical personnel wearing barrier clothing protecting against infectious agents are at risk of heat stress resulting from limited heat exchange with the environment. The aim of the study was to assess the impact of changing underwear on the thermal parameters of protective clothing sets and on the expected safe working time. The study used a Newton thermal manikin to determine the thermal insulation and water vapor resistance of clothing sets consisting of three types of underwear (standard medical underwear and short and long thermal underwear) worn under two types of barrier suits. The obtained data were used to conduct physiological simulations in the Predicted Heat Strain (PHS) program, estimating the time it takes for core body temperature to rise to 38 °C in conditions of 22 °C and 35 °C. The results showed that replacing medical underwear with thermal underwear at 22 °C extended safe working time by 24%. In hot conditions (35 °C), the positive impact was smaller, extending working time by a maximum of 4%. Changing the inner layer is an effective method of improving comfort and safety in barrier clothing, especially in thermoneutral conditions. Full article

Elevated ambient temperature is the primary abiotic element that possibly diminishes production and economic profitability in the chicken industry. The current study evaluated the role of dietary addition of Spirulina platensis (SP) and humic acid (HA) in mitigating the effects of acute cyclic heat stress on growth performance, meat quality, immune status, and intestinal morphology in broiler chickens. Five hundred three-day-old male Ross 308 broiler chicks (average body weight 101.42 ± 3.22 g) were assigned to five experimental groups, each with 10 replicates (10 birds per replicate). The chicks in the first group received a basal diet and were maintained in thermoneutral conditions (NEG CON). The remaining four groups received either a basal diet only (POS CON) or a basal diet added with SP (2 g/kg of feed; SP group), HA (5 g/kg of feed; HA group), or a mix of SP and HA by the same doses (SP+HA group). The four groups were exposed to acute cyclic heat stress (36 °C ± 2 °C) from the 22nd to the 25th day of age for 6 h/day. The HA group showed increased body weight and body weight gain, and improved feed conversion ratio compared with other groups (p < 0.001). The addition of SP and HA improved sensory characteristics and reduced the dripping losses of the breast muscles. The phagocytic % and phagocytic index were higher in the SP group compared with the NEG and POS CON. The serum levels of triiodothyronine and thyroxine were higher in the HA and SP+HA groups compared with the control groups. The serum concentrations of interleukin-10, complement 3, and lysozymes, as well as the liver concentrations of HSP90A and HSP90B, were higher in the SP, HA, and SP+HA groups compared with the NEG and POS CON. The duodenal villous height and width were significantly greater in the HA group compared to the other groups. Spleen histomorphology in the SP and HA groups was better than that of the POS CON. The HA group showed up-regulation in the immune expression of clusters of differentiation 3 (CD3) and 20 (CD20) proteins in the spleen tissues. In conclusion, both HA and SP, individually but not in combination, mitigated the detrimental effects of acute cyclic heat stress on growth and immunity. Humic acid addition provided the most pronounced improvements in performance and intestinal morphology. Further studies are warranted to clarify the biochemical interactions between SP and HA under different stress intensities. Full article

This study aimed to investigate the hematological, biochemical, short-chain fatty acids (SCFAs) content, and histomorphological responses of laying hens exposed to different thermal stress conditions and fed a diet supplemented with 6% white grape pomace (WGP). The research was part of a large six-week experimental trial conducted on 240 Lohmann Brown hens (58 weeks old), arranged in a 2 × 3 factorial design with two dietary treatments (control and WGP) conducted under thermoneutral (NT, 22 °C), high thermal stress (HST, 35 °C), and low thermal stress (LST, 10 °C) conditions. HST conditions significantly lowered the production performances of ALBW (average live body weight; p = 0.0001) and ACW (average carcass weight; p = 0.026) and significantly increased the heterophil/lymphocyte (H:L) ratio and platelets concentration (p < 0.05). Serum K values decreased and the Na/K ratio increased significantly (p = 0.001) under both HST and LST conditions; total protein (TP) decreased significantly under HST (p = 0.031). Significantly decreased (p < 0.001) feed intake and excreta were registered under HST conditions. Concerning SCFAs content, isobutyrate was higher under LST (p = 0.0001), while butyrate showed higher values under NT conditions for the WGP group (p = 0.002). Intestinal morphometry was highly influenced by high temperatures (shorter villi, deeper crypts). Overall, the 6% WGP supplementation, a natural high antioxidant resource, produced modest, context-dependent effects, with benefits under NT and LST conditions but insufficient to protect against the negative effects of chronic heat stress. Full article

Heat stress (HS) is an environmental variable challenging pig production worldwide. It may alter carcass composition by increasing fat deposition but the mechanisms are poorly understood. Betaine is a metabolic modifier able to decrease carcass fat in pigs, but the effects of betaine on lipolysis under high temperatures are not known. Our goal was to determine a potential effect of betaine on lipolysis in the fat tissue of Iberian pigs under thermoneutral (TN) or HS conditions. Eight pigs (89 kg BW) were used to obtain explants from dorsal subcutaneous adipose tissue. Explants were cultivated under TN (37 °C) or HS conditions (41.5 °C) for 1.5 h to study direct effects of HS on acute lipolysis. Treatments included control and betaine addition (200 µM). Indirect effects of HS were examined using the culture medium amended with 1 μM isoproterenol ±10 nM insulin in the presence or absence of betaine and HS. Media glycerol was measured at the end of the incubations as a proxy of lipolysis. HS decreased basal lipolysis (−47%; p < 0.001) but increased isoproterenol-stimulated (a β-agonist) lipolysis (+31%; p < 0.01). Betaine increased non-stimulated lipolysis both under TN and HS conditions (73%; p < 0.001). As expected, isoproterenol augmented lipolysis both in TN (2714%; p < 0.001) and HS (3589%; p < 0.001) conditions. The addition of insulin to lipolysis-stimulated explants analogously diminished glycerol release in TN (−39%; p < 0.001) and HS (−50%; p < 0.001) conditions. In conclusion, HS reduced non-stimulated lipolysis in Iberian pigs in line with increased adipose tissue accretion, while betaine partly increased lipolysis, counteracting the effects of HS. Betaine supplementation could be a strategy to counteract HS-induced fattening in pigs. Full article

To explore effects of sleep restriction (SR) on next-morning cognitive recovery of young males under thermoneutral environments, three SR conditions, namely the mild (ending at 01:20), moderate (ending at 02:30) and severe sleep restriction (ending at 03:40), were carried out on participants in a thermoneutral environment. During experiments, the subjective sleepiness, perceived workload, and thermal sensation were surveyed. Electrocardiogram (ECG) data were recoded continuously to conduct the heart rate variability (HRV) analysis. In addition, the Deary–Liewald task (including the Simple Response Time task and the Choice Response Time task), Stroop task and Corsi Block task were completed. Results revealed significant increases in sleepiness and perceived workloads during SR. In addition, mean heart rate reduced significantly during moderate (ΔHR = −9.48, p < 0.05) and severe SRs (ΔHR = −9.69, p < 0.01), although it returned to the baseline level in the next morning. The root mean square of successive differences (RMSSD) was elevated during all SRs (Mild SR ΔRMSSD = 27.34, p < 0.05; Moderate SR ΔRMSSD = 33.06, p < 0.01; Severe SR ΔRMSSD = 24.61, p < 0.05) but reduced to baseline the next morning. Furthermore, the sustained attention (SRT) and selective attention performances (CRT) were impaired significantly under moderate (SRT ΔPI = −0.59, p < 0.05; CRT ΔPI = −0.24, p < 0.05) and severe SR (SRT ΔPI = −0.39, p < 0.05; CRT ΔPI = −0.42, p < 0.01). However, the sustained attention performance was restored the next morning even after severe SR, whereas the selective attention performance remained impaired (ΔPI = −0.36, p < 0.01). Significant reductions were observed in the Stroop task performance only after the severe SR (ΔPI = −0.17, p < 0.05), while short-term memory was slightly affected either during or after all SRs (p > 0.05). The overall cognitive performance reduced significantly after the moderate and severe SRs (Moderate SR ΔOPI = −0.30, p < 0.05; Severe SR ΔOPI = −0.40, p < 0.05), even in the next morning. Findings suggest that cognitive impairments caused by mild and moderate SRs could be partially recovered the next morning, while severe SR produced significant impairments in complex cognitive functions, potentially linked to parasympathetic dysregulation and failure of prefrontal compensatory mechanisms. Preliminary findings from this study offer initial implications for cognitive preservation strategies in office environments after night-time overwork. Full article