Phase Engineered Composite Phase Change Materials for Thermal Energy Manipulation.

Phase change materials (PCMs) present a dual thermal management functionality through intrinsic thermal energy storage (TES) capabilities while maintaining a constant temperature. However, the practical application of PCMs encounters challenges, primarily stemming from their low thermal conductivity and shape-stability issues. Despite significant progress in the development of solid-solid PCMs, which offer superior shape-stability compared to their solid-liquid counterparts, they compromise TES capacity. Herein, a universal phase engineering strategy is introduced to address these challenges. The approach involves compositing solid-liquid PCM with a particulate-based conductive matrix followed by surface reaction to form a solid-solid PCM shell, resulting in a core-shell composite with enhanced thermal conductivity, high thermal storage capacity, and optimal shape-stability. The core-shell structure designed in this manner not only encapsulates the energy-rich solid-liquid PCM core but also significantly enhances TES capacity by up to 52% compared to solid-solid PCM counterparts. The phase-engineered high-performance PCMs exhibit excellent thermal management capabilities by reducing battery cell temperature by 15 °C and demonstrating durable solar-thermal-electric power generation under cloudy or no sunshine conditions. This proposed strategy holds promise for extending to other functional PCMs, offering a compelling avenue for the development of high-performance PCMs for thermal energy applications.

Embryonic thermal manipulation and post-hatch dietary guanidinoacetic acid supplementation alleviated chronic heat stress impact on broiler chickens.

The study investigated the effects of embryonic thermal manipulation (TM) and post-hatch guanidinoacetic acid (GAA) supplementation on male broiler chickens exposed to chronic heat stress (HS). Ross 308 eggs (n = 710) were randomly assigned to control (37.8 °C, 56% RH) or TM (39.5 °C, 65% RH for 12 h/day from embryonic day 7-16) treatments. After hatching, chicks were further assigned to four dietary treatments (n = 12 birds/pen, 5 replicates/treatment): control, control with 1.2 g/kg GAA supplementation (CS), TM, and TM with 1.2 g/kg GAA supplementation (TMS). All birds were subjected to chronic HS (32-36 °C and 55% RH for 6 h/day) from day 28-42. Embryonic TM treatment decreased hatchability, hatching weight (HW), and facial temperature (FT). During the pre-HS period (days 1-28), no significant differences in feed conversion ratio (FCR) and mortality were observed, although the TM group exhibited the lowest body weight gain (BWG). Following HS exposure (days 29-42), the TMS group displayed significantly higher BWG than the control and CS groups. The TM and TMS groups also demonstrated significantly lower FCR and mortality rates during this period. Across the entire period (days 1-42), BWG was significantly higher in the TMS group compared to other groups. Furthermore, TM and TMS treatments were associated with lower mortality rates, improved FCR, better European Performance Efficiency Index (EPEI), and reduced abdominal fat deposition. The experimental treatments did not significantly affect intestinal morphology or most blood parameters, except triiodothyronine (T3), thyroxine (T4), and uric acid. Plasma concentrations of T3, T4, and uric acid were significantly lower in the TM and TMS groups compared to the control and CS treatments. The findings suggest that a combined strategy of embryonic TM and post-hatch dietary GAA supplementation may not only alleviate the detrimental effects of HS but also promote beneficial physiological responses in broiler chickens.

Fasting/refeeding: an experimental model to study the impact of early thermal manipulation on hepatic metabolism in mule ducks.

An increase in egg incubation temperature was previously shown to enhance the metabolism of mule ducks and increase liver fattening after overfeeding, through a metabolic programming mechanism. Here, we examined whether fasting (F) followed by refeeding (RF) in 11-wk-old mule ducks could become an accelerated model to study the mechanisms of metabolic programming following embryonic thermal manipulation. This study investigated the hepatic response of mule ducks subjected to 23 h of fasting and 1 h of refeeding, in control or thermally programmed animals (with an increase of 1°C, 16 h per day from days 13 to 27 of embryogenesis). Liver weight and energy composition, hepatocyte structure, plasma parameters, and gene expression levels were measured at 1, 2, and 4 h after RF. All these parameters were strongly affected by RF, whereas significant impacts of embryonic programming were measured in cell size (+1 µm on average), lipid composition (+4.2% of saturated fatty acids 4 h after the meal), and relative gene expressions (including HK1, SCD1, ELOVL6, and FASN). In addition to confirming previously identified molecular targets of thermal manipulation, this study revealed new ones, thanks to kinetic sampling after RF. Finally, the detailed description of the impact of the F/RF challenge on the liver structure, composition, and gene expression, but also on plasma parameters allowed us to draw a parallel with these same traits measured during overfeeding. This comparative analysis suggests that this protocol could become a pertinent model to study the mechanisms involved in embryonic liver thermal programming, without overfeeding.

Chicken embryo thermal manipulation alleviates postnatal heat stress-induced jejunal inflammation by inhibiting Transient Receptor Potential V4.

Intestinal inflammation induced by heat stress is an important factor restricting the healthy growth of broilers. The aim of this study was to evaluate the effect of chicken embryo thermal manipulation (39.5 â„ƒ and 65 % RH for 3 h daily during 16-18 th embryonic age) on intestinal inflammation in broilers under postnatal heat stress and to investigate whether transient receptor potential V4 (TRPV4) plays a role in this process. Our results suggest that broilers with embryo thermal manipulation experience could delay the rising of rectal temperature during postnatal heat stress (P < 0.05), and had better production performance (P < 0.05), intestinal morphological parameters (P < 0.05) and higher expression of tight junction related genes (P < 0.05). The increased serum lipopolysaccharide (LPS) content, activation of nuclear factor-kappa B (NF-κB) signaling pathway and the increased expression of pro-inflammatory cytokines interleukin (IL)-1ß, IL-6 and tumor necrosis factor alpha (TNF-α) in jejunum during postnatal heat stress were alleviated by embryo thermal manipulation (P < 0.05). Postnatal heat stress induced an increase in mRNA and protein expression of TRPV4 in jejunum (P < 0.05), but had no effect on broilers which experienced embryo thermal manipulation (P > 0.05). Inhibition of TRPV4 reduced LPS-induced Ca2+ influx and restrained the activation of NF-κB signaling pathway and the expression of downstream pro-inflammatory cytokines (P < 0.05). The expression of DNA methyltransferase (DNMT) in the jejunum of broilers exposed to postnatal heat stress was increased by embryo thermal manipulation (P < 0.05). The DNA methylation level of TRPV4 promoter region was detected, and the results showed that embryo thermal manipulation increased the DNA methylation level of TRPV4 promoter region (P < 0.05). In conclusion, Chicken embryo thermal manipulation can alleviate jejunal inflammation in broilers under postnatal heat stress. This may be due to the decreased circulating LPS or the increased DNA methylation level in the promoter region of TRPV4, which inhibits TRPV4 expression, thereby reducing Ca2+ influx, and finally alleviating inflammation by affecting NF-κB signaling pathway. The work is an attempt to understand the mechanism involved in alleviation of adverse effects of heat stress during postnatal life through prenatal thermal manipulation and to reveal the important role of epigenetics.

The effects of exposure to cold during incubation on developmental stability, fear, growth, and carcass traits in Japanese quails.

The aim of this study was to determine the effects of 6 h/day cold (35.0 °C) acclimatization between the 9th and 15th days of incubation of Japanese quail embryos on hatchability, livability, chick quality, developmental stability, fear response, live weight, and slaughter-carcass characteristics. Two homologous incubators and a total of 500 hatching eggs were used in the study. Randomly selected half of the eggs were exposed to cold according to the eggshell temperature. The cold acclimation of Japanese quail embryos had no adverse effects on all mentioned traits, except for chick quality. Chicks in the control group had higher Tona scores (99.46) than those exposed to cold (99.00) (P < 0.05). In addition, there were differences among the treatment groups in terms of the parameters of mature weight (ß0), instantaneous growth rate (ß2), and inflection point coordinates of the Gompertz growth model (P < 0.05 for all). It was found that exposing embryos to cold during the incubation changed the shape of the growth curve. As the development of embryos exposed to cold slows down, a compensatory growth occurs in the early posthatch period. Thus, the growth rate increased in the period before the inflection point of the growth curve.

Effect of thermal manipulation on the biological and mechanical characteristics of horizontal platelet rich fibrin membranes.

BACKGROUD: Regardless of application scenarios, proper mechanical characteristics and degradation properties are prerequisites for horizontal platelet rich fibrin (H-PRF) to manifest its ability. Among the methods used to modify PRF, thermal manipulation is promising as it is easy to handle without adding extra additives. Yet there is no consensus on optimal temperature treatment. This study aimed to investigate the effects of heating on the biological and mechanical characteristics of H-PRF and explore the optimum heating temperature for H-PRF thermal treatment. METHODS: We employed a series of temperature gradients, room temperature, 50℃, 75℃, 90℃, 105℃. The microstructure and the mechanical properties were recorded by Scanning Electron Microscope (SEM) and tensile strength tests respectively. The degradation rate of H-PRF membranes was examined by digestion assay with plasmin and trypsin. The viability of cells within H-PRF membranes and the proliferation of osteoblasts cultured with extracts from different H-PRF groups was evaluated using CCK-8 assays. RESULTS: Compared with the nonheated group, overheated manipulation beyond 90℃ can significantly prolong the degradation properties for up to 3 to 4 weeks and enhance the mass stress of H-PRF membranes. A high-temperature treatment of 105℃ accompanied by the cell activity beneath H-PRF reduced more than half, and thus, the biological effect on human osteoblasts (hFOBs) also reduced dramatically. CONCLUSIONS: High thermal manipulation can prolong the degradation properties and enhance the mechanical properties of PRF membranes accompanied by the loss of biological effect.

Effects of cooling or warming of the distal upper limb on skin vascular conductance and brachial artery shear profiles during cycling exercise.

The relative influence of skin vascular conductance in glabrous (G; palm) and non-glabrous (NG; dorsal and forearm) regions to upstream brachial artery-shear stress (BA-SS) profile are unknown. This study aimed to elucidate the effects of G and/or NG skin vascular conductance (VC), which were modulated by warming or cooling manipulation, on BA-shear rate (SR, an estimate of SS) during cycling exercise. Seven healthy subjects performed 60-min exercise. Between 20 and 50 min of the exercise, the NG+G or G skin region were warmed to 42°C or cooled to 15°C using a water bath. Throughout the protocol, diameter and blood velocity in BA and skin VCs in forearm and palm were measured. All measurements showed that a steady-state response was reached after 20 min of exercise. Subsequently, during cooling manipulation, forearm VC was significantly decreased, and the concomitant BA-SR profile was revealed (primarily characterized by decreased antegrade SR and increased retrograde SR) in the NG+G. Such changes were not observed in G alone. During warming manipulation, forearm VC and mean BA-SR significantly increased only in the NG+G. In conclusion, vascular response in NG skin possibly plays a major role in the modulation of BA-SS profile during cycling exercise.

Embryonic thermal manipulation impacts the postnatal transcriptome response of heat-challenged Japanese quails.

BACKGROUND: The thermal-manipulation (TM) during egg incubation is a cyclic exposure to hot or cold temperatures during embryogenesis that is associated to long-lasting effects on growth performance, physiology, metabolism and temperature tolerance in birds. An increase of the incubation temperature of Japanese quail eggs affected the embryonic and post-hatch survival, growth, surface temperatures and blood characteristics potentially related to thermoregulation capacities. To gain new insights in the molecular basis of TM in quails, we investigated by RNA-seq the hypothalamus transcriptome of 35 days-old male and female quails that were treated by TM or not (C, control) during embryogenesis and that were exposed (HC) or not (RT) to a 36 °C heat challenge for 7 h before sampling. RESULTS: For males, 76, 27, 47 and 0 genes were differentially expressed in the CHC vs. CRT, CRT vs. TMRT, TMHC vs. TMRT and CHC vs. TMHC comparisons, respectively. For females, 17, 0, 342 and 1 genes were differentially expressed within the same respective comparisons. Inter-individual variability of gene expression response was observed particularly when comparing RT and HC female animals. The differential expression of several genes was corroborated by RT-qPCR analysis. Gene Ontology functional analysis of the differentially expressed genes showed a prevalent enrichment of terms related to cellular responses to stimuli and gene expression regulation in both sexes. Gene Ontology terms related to the membrane transport, the endoplasmic reticulum and mitochondrial functions as well as DNA metabolism and repair were also identified in specific comparisons and sexes. CONCLUSIONS: TM had little to no effect on the regulation of gene expression in the hypothalamus of 35 days-old Japanese quails. However, the consequences of TM on gene expression were revealed by the HC, with sex-specific and common functions altered. The effects of the HC on gene expression were most prominent in TM females with a ~ 20-fold increase of the number of differentially expressed genes, suggesting that TM may enhance the gene response during challenging conditions in female quail hypothalamus. TM may also promote new cellular strategies in females to help coping to the adverse conditions as illustrated by the identification of differentially expressed genes related to the mitochondrial and heat-response functions.

Differential expression of small heat shock proteins in the brain of broiler embryo; the effects of embryonic thermal manipulation.

Broilers are more vulnerable to high temperatures than mammals due to the feather cover, lack of sweat glands, fast growth and intensive breeding in commercial systems. Thermal stresses affect the function of various organs and change the expression profiles of hundreds of genes in the different tissues of broilers. Thermal manipulation (TM) during embryogenesis can increase heat tolerance in growing broilers. Small heat shock proteins (SHSPs) are a group of HSPs which participate in many cellular functions like response to different stressors. However, their role in the thermotolerance has not been fully elucidated. Ninety fertilized eggs were randomly divided into three groups (30 eggs/group; 10 eggs/replicate). Normal control (NC) eggs were incubated at 37.5 °C throughout the incubation period whereas heat stress (HS) and cold stress (CS) groups were kept at 41 °C and 33 °C from 15 to 17th day of incubation for 3 h each day, respectively. On day 20, samples from the cerebrums were harvested for histopathology and mRNA expression analyses of HSPB1, HSPB5, HSPB8, and HSPB9. There were no significant differences in survivability, defected embryos, hatchability, and body weight among treatments. TM had no major deleterious effects on the cerebral tissue except for mild degeneration in the HS group. HSPB1, HSPB5, HSPB8, and HSPB9 were expressed in the presence and absence of TM. All SHSP genes tested were downregulated in response to TM except for HSPB9 which was upregulated in the HS group. The highest change in gene expression due to TM observed for HSPB1. This study presents a broader understanding of mechanisms underlying response to TM in broilers. The results suggest that HSPB1, HSPB5, HSPB8, and HSPB9 are involved in thermotolerance in broilers and SHSPs could be involved in the gene expression profiling of TM. It may propose the use of nutritional supplements in the poultry industry to modulate SHSPs.

Thermal manipulation of the broilers embryos: expression of muscle markers genes and weights of body and internal organs during embryonic and post-hatch days.

BACKGROUND: In broilers chickens, the molecular bases for promoting muscle development and growth requires further investigation. Therefore, the current study aimed to investigate the effects of daily thermal manipulation (TM) during embryonic days (ED) 12 to 18 on body, carcass and internal organ weights as well as on the expression of muscle growth markers genes during late embryogenesis and post-hatch days. 1500 fertile Cobb eggs were divided into five groups. The first group was a control group and incubated at 37.8°C. The other four groups were thermally manipulated (TM) and exposed to 38.5°C (TM1), 39°C (TM2), 39.5°C (TM3) and 40°C (TM4) daily for 18 h, respectively, with a relative humidity of 56%. Body weights (BW) from ED 12 to 18 and on post-hatch days 1, 2, 3, 4, 5, 6, 7, 14, 21, 28 and 35 were recorded. mRNA expression levels of muscle growth factor genes (IGF-1 and GH) and muscle marker genes (Myogenic Differentiation Antigen; MyoD), Myogenin, Pax7, and PCNA) during ED 12 to 18 and on post-hatch days 1, 3, 5, 7, 14 were analyzed. On post-hatch day 35, the carcass and internal organ weights have been also evaluated. RESULTS: TM during certain days of embryogenesis (ED 12 to 18) did not affect the BW of broilers during their embryonic lives. However, TM, particularly TM1 and TM2, significantly increased BW, carcass and internal weights of hatched chicks near to the marketing age (post-hatch days 28 and 35). Most of TM protocols induced up-regulation of muscle growth factor genes (IGF-1 and GH) and muscle marker genes (MyoD, Myogenin, Pax7, and PCNA) during embryonic life (ED 12 to 18) and on post-hatch days. CONCLUSION: Among the various TM conditions, it seems that,TM1 and TM2 induced a significant increase in BW, carcass and internal weights of hatched chicks near to the marketing age. This increase in BW induced presumably via up-regulation of muscle growth factor genes and muscle growth markers genes during embryonic life (ED 12 to 18) and on post-hatch days. Both protocols (TM1 and TM2) can be used in real-world applications of poultry industry for maximum benefit.

Basal and dynamics mRNA expression of muscular HSP108, HSP90, HSF-1 and HSF-2 in thermally manipulated broilers during embryogenesis.

BACKGROUND: Limited data are available about the kinetics of mRNA expressions of Heat shock proteins (HSPs) and heat shock factors (HSFs) in the thermally manipulated (TM) broiler chicks during acute heat stress. Therefore, this study aimed to investigate effects of thermal manipulation (TM) of broiler chicken during embryonic days (ED) 12-18 on the basal and dynamics mRNA expression of heat shock proteins (HSP108 and HSP90) and heat shock factors (HSF-1 and HSF-2) in the muscle tissue during late embryogenesis, first week of life and during heat stress (HS) on post-hatch days 14 and 28. One thousand and five hundred fertile Ross 315 broiler eggs were randomly allocated to five groups: control group (37.8 °C), TM1 (38.5 °C for 18 h), TM2 (39 °C for 18 h), TM3 (39.5 °C for 18 h) and TM4 (40 °C for 18 h). Chicks from each treatment group were then randomly sub-divided into two further treatment groups, naïve and thermal challenged (TC). On post-hatch days 14 and 28, thirty chicks from each TC group were subjected to heat stress (41 °C for 6 h), while naïve chicks of each group (n = 30) were kept under regular conditions. The response of chicks to heat stress was investigated by evaluating the change in mRNA expressions of HSP108, HSP90, HSF-1 and HSF-2 in muscle tissue after 1, 3 and 5 h of heat stress. RESULTS: When compared to the control group, TM resulted in significant increases in the basal mRNA expression of HSPs and HSFs during embryogenesis and altered their dynamic expressions in the muscle tissue after heat stress on post-hatch days 14 and 28. CONCLUSION: the current study indicated short- and long-term enhancement of HSPs and HSFs gene expression which was associated with acquisition of improved thermotolerance in thermally manipulated chicks.

l-Leucine acts as a potential agent in reducing body temperature at hatching and affords thermotolerance in broiler chicks.

Thermal manipulation (TM) of incubation temperature causes metabolic alterations and contributes to improving thermotolerance in chicks post hatching. However, there has been no report on amino acid metabolism during TM and the part it plays in thermotolerance. In this study, we therefore first analyzed free amino acid concentrations in the embryonic brain and liver during TM (38.6°C, 6h/d during embryonic day (ED) 10 to ED 18). It was found that leucine (Leu), phenylalanine and lysine were significantly decreased in the embryonic brain and liver. We then chose l-Leu and other branched-chain amino acids (l-isoleucine (L-Ile) and l-valine (l-Val)) for in ovo injection on ED 7 to reveal their roles in thermoregulation, growth, food intake and thermotolerance in chicks. It was found that in ovo injection of l-Leu, but not of l-Ileu or l-Val, caused a significant decline in body temperature at hatching and increased food intake and body weight gain in broiler chicks. Interestingly, in ovo injection of l-Leu resulted in the acquisition of thermotolerance under high ambient temperature (35±1°C for 180min) in comparison with the control thermoneutral temperature (28±1°C for 180min). These results indicate that the free amino acid concentrations during embryogenesis were altered by TM. l-Leu administration in eggs caused a reduction in body temperature at hatching, and afforded thermotolerance in heat-exposed young chicks, further suggesting that l-Leu may be one of the key metabolic factors involved in controlling body temperature in embryos, as well as in producing thermotolerance after hatching.

Thermal manipulation during embryogenesis affects myoblast proliferation and skeletal muscle growth in meat-type chickens.

Thermal manipulation (TM) of 39.5°C applied during mid-embryogenesis (embryonic d 7 to 16) has been proven to promote muscle development and enhance muscle growth and meat production in meat-type chickens. This study aimed to elucidate the cellular basis for this effect. Continuous TM or intermittent TM (for 12 h/d) increased myoblast proliferation manifested by higher (25 to 48%) myoblast number in the pectoral muscles during embryonic development but also during the first week posthatch. Proliferation ability of the pectoral-muscle-derived myoblasts in vitro was significantly higher in the TM treatments until embryonic d 15 (intermittent TM) or 13 (continuous TM) compared to that of controls, suggesting increased myogenic progeny reservoir in the muscle. However, the proliferation ability of myoblasts was lower in the TM treatments vs. control during the last days of incubation. This coincided with higher levels of myogenin expression in the muscle, indicating enhanced cell differentiation in the TM muscle. A similar pattern was observed posthatch: Myoblast proliferation was significantly higher in the TM chicks relative to controls during the peak of posthatch cell proliferation until d 6, followed by lower cell number 2 wk posthatch as myoblast number sharply decreases. Higher myogenin expression was observed in the TM chicks on d 6. This resulted in increased muscle growth, manifested by significantly higher relative weight of breast muscle in the embryo and posthatch. It can be concluded that temperature elevation during mid-term embryogenesis promotes myoblast proliferation, thus increasing myogenic progeny reservoir in the muscle, resulting in enhanced muscle growth in the embryo and posthatch.

Thermal manipulations of turkey embryos: The effect on thermoregulation and development during embryogenesis.

Previous studies conducted on meat-type chickens in our laboratory showed that thermal manipulations (TMS:) of the embryo during the time window of the hypothalamus-hypophysis-thyroid axis development and maturation significantly reduced the metabolic rates of the embryo and the chicken, improving the posthatch feed conversion rate (FCR:). The aim of the present study was to investigate the effect of intermittent TMs during turkey embryogenesis on embryo development. Fertile turkey eggs were divided into three treatments: control; 6H--with TM by elevation of temperature and RH by 1.7°C and 9%, respectively, above the control conditions for 6 h/d, from E10 through E22, i.e., 240 through 552 h of incubation; and 12H--with TM as above, for 12 h/d, during the same time period. From E0 through E10 and from E23 onward all eggs were incubated under control conditions. The embryo growth rate was not negatively affected by TM. During TM eggshell temperature, the embryonic heart rate and oxygen consumption were elevated by the manipulation while the embryos were in their ectothermic phase. However, by the end of the TM period and until hatch (the endothermic phase) these parameters were significantly lower in both TM treatments than in the control, indicating a lower metabolic rate and heat production. The TM embryos hatched approximately 10 h earlier than the controls, without any negative effects on chick body weight or hatchability. Nevertheless, TM treatments resulted in a higher proportion of chicks with unhealed navels. Body temperature at hatch was significantly lower in the TM chicks than in the controls, suggesting lower heat production and metabolic rate, which might affect the energy requirements for posthatch maintenance. It was concluded that TM during turkey embryogenesis might have altered the thermoregulatory set point, and thus lowered the embryo metabolic rate, which might have a long-lasting posthatch effect.

Effect of thermal manipulation during embryogenesis on liver heat shock protein expression in chronic heat stressed colored broiler chickens.

Thermal manipulation during embryogenesis has been shown to improve thermo tolerance in broilers. Heat shock proteins are a family of proteins produced in response to variety of stress and protect cells from damage. The aim of this study was to evaluate the effect of thermal manipulation (TM) during embryogenesis on HSP gene and protein expression in the embryos and in chronic heat stressed 42nd day old chicks. On 15th day of incubation, fertile eggs from two breeds-Naked neck (NN) and Punjab Broiler-2 (PB-2) were randomly divided in to two groups, namely Control (C) eggs were incubated under standard incubation conditions and Thermal Conditioning (TC) eggs were exposed to higher incubation temperature (40.5°C) for 3h on 15th, 16th and 17th day of incubation. The chicks so obtained from each group were further subdivided and reared from 15th-42nd day as normal (N; 25±1°C, 70% RH) and heat exposed (HE; 35±1°C, 50% RH) resulting in four treatment groups (CN, CHE, TCN and TCHE). Embryos of two groups (C and TC) on 17th day and birds from four treatment groups on 42nd day were sacrificed. Liver was collected for analysis of gene expression by real-time PCR and protein expression by Western blot of Heat Shock Proteins (HSP 90 alpha, HSP 90 beta, HSP 70, HSP 60, HSP 27 and ubiquitin). The plasma collected on 42nd day was analyzed for biochemical parameters. Thermal challenging of embryos of both the breeds caused significant (P≤0.05) increase in all the HSPs gene and protein expression. The TCHE chicks had significantly (P≤0.05) lower HSPs gene and protein expressions and oxidative stress compared to CHE groups in both NN and PB-2. Based on these findings it can be concluded that TM during incubation provides adaptation to broiler chicks during chronic heat stress.

Influence of in ovo thermal manipulation on lipid metabolism in embryonic duck liver.

The growth and development of poultry embryos are easily affected by environmental factors, such as the incubation temperature and humidity. Metabolism, including lipid metabolism, during the embryonic stage is also important for the growth and development of poultry. Our study aimed to investigate the effects of incubation temperature on embryonic lipid metabolism in the liver of ducks. To fully evaluate the effects, thermal treatment was given between embryonic ages 11 and 24 days with a 1 °C higher incubation temperature than the control group, and lipid metabolism parameters in the liver and blood serum were analyzed both at embryonic stage day 20 and 2 weeks post-hatching. Our results showed no significant changes in the embryonic stage in total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in the blood serum (P>0.05). Additionally, the mRNA expression levels and enzyme activities of fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), and elongase of very long chain fatty acids (ELOVL) did not show significant changes either in the embryonic stage or at hatching day 20 (P>0.05). However, there were significant changes in the gene expression and enzyme activities of TC, LDL-C and FAS at post-hatching stages (P≤0.05). These results may indicate that the thermal treatment has less influence on lipid metabolism in the embryonic stage but has a much stronger effect in the post-hatching stage.

Embryonic thermal manipulation reduces hatch time, increases hatchability, thermotolerance, and liver metabolism in broiler embryos.

The broilers' health and growth performance are affected by egg quality, incubation conditions, and posthatch management. Broilers are more susceptible to heat stress because they have poor thermoregulatory capacity. So, it is crucial to develop a strategy to make chicks thermotolerant and cope with heat stress in post-hatch life. This study investigated the effects of embryonic thermal manipulation (TM) on different hatching parameters (hatch time, hatchability, and hatch weight), brain thermotolerance, and liver metabolism. Six hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5°C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19-21, standard temperature, 37.5°C) and 236 eggs were incubated at a standard temperature (37.5°C) till hatch. The samples were collected from the Control and TM groups on ED 15 and 18 of the embryonic periods. Hatchability was significantly higher (P < 0.05) in the TM group (94.50%) than in the control group (91.0%). Hatch weight did not differ significantly between the TM group (50.54 g) and the Control group (50.39 g). Most importantly, hatch time was significantly lower (P < 0.05) in the TM group than in the Control. In the D15 embryo brain, the mRNA expression of TRPV1,TRPV2, TRPV3, and the epigenetic marker H3K27 were significantly lower (P < 0.05) in the TM group compared to the Control group. However, in the D18 brain, the expression of TRPV1, TRPV2, and CRHR1 was significantly higher (P < 0.05) in the TM group than in the Control group. In the liver, the mRNA expression of SLC6A14 was significantly lower (P < 0.05) in the D15 TM group than in the D15 Control group. Conversely, the DIO3 mRNA expression was significantly higher (P < 0.05) in the D15 TM group than in the D15 Control group. The expression of GPX3, FOXO1, IGF2, and GHR in the liver was significantly higher in the D18 TM group compared to the D18 Control group (P < 0.05). In conclusion, increased expression of the aforementioned markers during the later embryonic period has been linked to reduced hatch time by increasing liver metabolism and thermotolerance capacity in the brain.

Embryo thermal manipulation modifies development and hepatic lipid metabolism in post-hatch layer-type chicks.

Incubation temperature is a crucial environmental factor affecting embryonic development and chick quality. Metabolism during the embryonic stage, particularly liver lipid metabolism, is essential for the growth and development of poultry. This study aimed to investigate the effects of embryo thermal manipulation with high (TMH, 39.5 °C, 65% RH, 8 h/d) and low (TML, 20 °C, 65% RH, 1 h/d) temperatures during 8th to 15th embryonic age on hatching performance and liver lipid metabolism in layer chicks. Additionally, the duration of TM effects was evaluated through a short-term feeding trial. The results indicated that TMH accelerated the hatching process without significantly affecting hatchability and growth performance. In contrast, TML delayed hatching time and significantly reduced hatchability and chick quality. After hatching, TML also increased residual yolk weight and reduced the relative liver weight in relation to body weight and yolk-free body mass. Moreover, lipid droplets in the liver were stained with Oil Red O, and the lipid content in the liver and serum was further detected. TMH had no significant impact on triglyceride (TG) and total-cholesterol (TCHO) content in the liver and serum but upregulated the expression of lipogenesis-related genes ACC, Fas, and Fatp1 compared to the TML group. Conversely, TML significantly reduced liver TG content, enhanced lipoprotein lipase (LPL) activity, and promoted the expression of lipid oxidation-related genes CPT-1, PGC-1α, and PPARα. At 7 d of age, liver LPL activity was significantly increased in the TMH group. However, there were no significant changes in the content of TG and TCHO in the liver and the expression of lipid metabolism-related genes in the TML group. Overall, these results indicate that embryonic TM alters hatching performance and liver lipid metabolism in layer chicks. TML reduces TG content by increasing liver lipid oxidation capacity. However, this effect is not long-lasting, as the influence of TM diminishes as the chicks develop.

Incubation temperature is a crucial environmental factor affecting embryonic development and chick quality. The liver is the primary tissue of lipid metabolism in poultry. During incubation, it is responsible for converting yolk fatty acids into forms usable by the embryo. However, it remains unclear whether changes in embryonic incubation temperature can affect liver lipid utilization. This study aimed to investigate the effects of embryo thermal manipulation with high temperature and low temperature on the hatching performance and liver lipid metabolism of layer chicks. The results showed that high incubation temperature had limited effects on hatchability and liver lipid metabolism, while low incubation temperatures not only delayed hatching time and significantly reduced hatchability, but also altered liver lipid metabolism and promoted the expression of genes related to lipid oxidation. However, these changes weakened or even disappeared as the chicks grew. This suggests that while embryo thermal manipulation affects the hatching performance and liver lipid metabolism of layer-type chicks, these effects are not persistent.

Pre-hatch thermal manipulation of embryos and post-hatch baicalein supplementation mitigated heat stress in broiler chickens.

BACKGROUND: High environmental temperatures induce heat stress in broiler chickens, affecting their health and production performance. Several dietary, managerial, and genetics strategies have been tested with some success in mitigating heat stress (HS) in broilers. Developing novel HS mitigation strategies for sustaining broiler production is critically needed. This study investigated the effects of pre-hatch thermal manipulation (TM) and post-hatch baicalein supplementation on growth performance and health parameters in heat-stressed broilers. RESULTS: Six hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5 °C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19 to 21, standard temperature) and 236 eggs were incubated at a controlled temperature (37.5 °C) till hatch. After hatch, 180-day-old chicks from both groups were raised in 36 pens (n = 10 birds/pen, 6 replicates per treatment). The treatments were: 1) Control, 2) TM, 3) control heat stress (CHS), 4) thermal manipulation heat stress (TMHS), 5) control heat stress supplement (CHSS), and 6) thermal manipulation heat stress supplement (TMHSS). All birds were raised under the standard environment for 21 d, followed by chronic heat stress from d 22 to 35 (32-33 °C for 8 h) in the CHS, TMHS, CHSS, and TMHSS groups. A thermoneutral (22-24 °C) environment was maintained in the Control and TM groups. RH was constant (50% ± 5%) throughout the trial. All the data were analyzed using one-way ANOVA in R and GraphPad software at P < 0.05 and are presented as mean ± SEM. Heat stress significantly decreased (P < 0.05) the final body weight and ADG in CHS and TMHS groups compared to the other groups. Embryonic TM significantly increased (P < 0.05) the expression of heat shock protein-related genes (HSP70, HSP90, and HSPH1) and antioxidant-related genes (GPX1 and TXN). TMHS birds showed a significant increment (P < 0.05) in total cecal volatile fatty acid (VFA) concentration compared to the CHS birds. The cecal microbial analysis showed significant enrichment (P < 0.05) in alpha and beta diversity and Coprococcus in the TMHSS group. CONCLUSIONS: Pre-hatch TM and post-hatch baicalein supplementation in heat-stressed birds mitigate the detrimental effects of heat stress on chickens' growth performance, upregulate favorable gene expression, increase VFA production, and promote gut health by increasing beneficial microbial communities.

Embryo thermal manipulation enhances mitochondrial function in the skeletal muscle of heat-stressed broilers by regulating transient receptor potential V2 expression.

Heat stress induces mitochondrial dysfunction, thereby impeding skeletal muscle development and significantly impacting the economic efficiency of poultry production. This study aimed to investigate the effects of embryo thermal manipulation (TM, 41.5°C, 65% RH, 3 h/d during 16-18th embryonic age) on the mitochondrial function of the pectoralis major (PM) in broiler chickens exposed to thermoneutral (24 ± 1°C, 60% RH) or cyclic heat stress (35 ± 1°C, 60% RH, 12 h/d) from day 22 to 28, and to explore potential mechanisms involving transient receptor potential V2 (TRPV2). Additionally, in vitro experiments were conducted to assess the regulatory effects of TRPV2 pharmacological activation and inhibition on mitochondrial function in primary myotubes. The results revealed that TM had no discernible effect on the body weight and feed intake of broiler chickens under heat stress conditions (P > 0.05). However, it did delay the increase in rectal temperature and accelerate the decrease in serum T3 levels (P < 0.05). Furthermore, TM promoted the development of PM muscle fibers, significantly increasing myofiber diameter and cross-sectional area (P < 0.05). Under heat stress conditions, TM significantly upregulated the expression of mitochondrial electron transport chain (ETC) genes and TRPV2 in broiler PM muscle (P < 0.05), with a clear positive correlation observed between the two (P < 0.05). In vitro, pharmacological activation of TRPV2 not only increased its own expression but also enhanced mitochondrial ETC genes expression and oxidative phosphorylation function by upregulating intracellular calcium ion levels (P < 0.05). Conversely, TRPV2 inhibition had the opposite effect. Overall, this study underscores the potential of prenatal thermal manipulation in regulating postnatal broiler skeletal muscle development and mitochondrial function through the modulation of TRPV2 expression.